C H A P T E R 1

Refractive Error and Its Correction: The Cornea and Its Physical Characteristics

Chapter 1

1.1 Refractive Error and Its Correction The cornea supplies most of the refracting power of the eye by virtue of its anterior curvature at the interface between different media (air and tissue) with significant differences in indices of refraction. When light rays travel through a transparent medium (such as air) and pass into a second transparent medium with a different density (such as water), they bend at the surface of the two media. This is known as refraction (see Fig. 1-1).

Fig. 1-1. Refraction of light rays passing from 2 air into water (Tortora & Anagnostakos).

The eye has four such media of refraction: the cornea, aqueous humor, lens and vitreous humor. In order for vision to occur, light must pass through all these media to reach the rods and cones of the retina, and then nerve impulses must conduct to the visual areas of the cerebral cortex to form a retinal image.

Light rays entering the eye from the air are refracted at the following points: (1) The anterior surface of the cornea as they pass from the lighter air into the denser cornea (2) The posterior surface of the cornea as they pass into the less dense aqueous humor (3) The anterior surface of the lens as they pass from the aqueous humor into the denser lens (4) The posterior surface of the lens as they pass from the lens into the less dense vitreous humor.

The degree of refraction that takes place at each surface of the eye is very precise. When an object is 6 metres or more away from the viewer, the light rays reflected from the object are nearly parallel to one another. The parallel rays must be bent sufficiently to fall exactly on the

4 central fovea, where vision is sharpest. This is known as emmetropia . Emmetropia is an optical condition in which there is no refractive error, so that rays of light parallel to the visual axis upon entering the eye are brought to a focus on the fovea centralis when no accommodation is exerted (see Fig. 1-2). There is an exact correlation between the refractive power of the anterior segment and the axial length of the eye. Clinically, this rarely occurs, because the correlation is not exact.

Fig. 1-2. In a normal or emmetropic eye, light rays from an object are bent sufficiently by the four refracting media and converged on the central fovea. A clear image is formed (Tortora & Anagnostakos). 2

Light rays that are reflected from near objects are divergent rather than parallel. As a result, they must be refracted toward each other to a greater extent. This change in refraction is brought about by the lens of the eye through the process known as accommodation . Accommodation is an ocular function in which optical power is increased by the eye in order to maintain a clear image as it moves closer (see Fig. 1-3). It occurs through a process of ciliary muscle contraction, which pulls the ciliary process and choroid forward toward the lens, releases the tension on the lens and suspensory ligament by zonular relaxation that causes the elastic-like lens to shorten. The increase in curvature and optical power bends the rays toward the central fovea to form a retinal image.

Fig. 1-3. Accommodation. (a) For objects at 6 meters or more. (b) For objects less than 6 meters (Tortora & Anagnostakos). 2

5 Conversely, in far vision, the ciliary muscle is relaxed and the lens is flatter. With aging, the lens loses elasticity and, therefore, its ability to accommodate. This condition is known as presbyopia .

Myopia is an optical condition in which rays of light entering the eye parallel to the visual axis come to a focus in front of the retina. The condition occurs because (1) the refractive power of the anterior segment is too great for the length of the eye or (2) the eye is too long for the refractive power present. Patients with uncorrected myopia do not accommodate to improve vision, because accommodation shifts the focal point even further anterior to the retina and blurs vision. Patients generally display certain degrees of difficulty in seeing distant objects, depending on the severity of the refractive error. Myopia is neutralized by concave lenses, which cause the parallel rays of light incident at the concave lens to focus at the far point of the eye, to be imaged by the optical system of the eye onto the retina (see Fig. 1-4). Thus, an infinite point would be conjugate with the retina after having passed through the combination of concave lens and the un-accommodated eye.

Fig. 1-4. In the myopic eye, the image is focused in front of the retina. The condition is corrected by a concave lens which diverges entering light rays so that they have to travel further through the eyeball and are focused exactly on the retina (Tortora and Anagnostakos). 2

Hyperopia is a refractive condition of the eye in which, with accommodation suspended, parallel rays of light are intercepted by the retina before coming into focus. The condition occurs because (1) the anterior segment is inadequate for the length of the globe or (2) the globe is too short for the amount of refractive power present (see Fig. 1-5). Accommodation increases the refractive power of the anterior segment and may compensate for mild degree of

6 hyperopia and provide normal vision. However, patients with a moderate or greater degree of hyperopia would have some difficulty in seeing near to intermediate distance objects. Hyperopia can be either latent or manifest. Latent hyperopia is that portion of the hyperopic error that is completely corrected by the eye’s own accommodation. The younger the patient, the greater the latent component. Manifest hyperopia may be subdivided into facultative and absolute types. Facultative hyperopia is the portion of the refractive error that may be measured and corrected by convex lenses but is also corrected by accommodation in the absence of lenses. A patient with facultative hyperopia will have normal visual acuity both with and without the convex lenses that correct this portion of the refractive error. The patient’s own accommodation can relax and permit the lenses to correct the error. Absolute hyperopia is the portion of the refractive error that cannot be compensated by the patient’s own accommodation. Both near and distance vision are blurred and the patient readily accepts convex lenses.

Fig. 1-5. In the hyperopic eye the image is focused behind the retina. The condition is corrected by a convex lens which converges entering light rays so that they focus exactly on the retina (Tortora and Anagnostakos). 2

As stated earlier, the amplitude of accommodation decreases as the patient ages. There is a tendency to go from latent to manifest hyperopia and need a reading correction (or bifocal if there is also distant refractive error). This is known as presbyopia.

Presbyopia is an optical condition of decreased accommodation which occurs normally in middle-aged and older individuals. As described earlier, the process of accommodation brings about change in the shape of the elastic-like lens when focused on a near object. With each year of life the lens loses some of its elasticity, decreasing the amount of accommodation. Generally, there are about 14 diopters of accommodation at 10 years of age and only 2

7 diopters of accommodation by 50 years of age. The decrease occurs gradually, in all individuals, irrespective of their refractive error. However, mildly myopic people have an advantage, as they are able to read comfortably without additional lenses due to the nature of myopic eye described previously. A moderately myopic individual may compensate for presbyopia by removing the lens that corrects distance vision. Presbyopia, however, is aggravated in a hyperopic individual if the lens that corrects the hyperopia is removed. The main symptom of presbyopia is inability to see near work distinctly, which is aggravated in dim illumination and with small print. Other symptoms can be ocular discomfort, headaches, and tired eyes, especially if the person attempts to persist with reading or doing close work, and annoyance at having to place reading material further away from the eyes than previously.

Presbyopia is corrected by means of convex lenses added to the distance correction. This is known as “near add”. The power of the lens required to achieve clear near vision varies with an individual’s habits, age, occupation, and accustomed distance of doing near work. Generally the weakest possible “near add” is prescribed, and increases as the patient grows older; the maximum is usually +3.0 or +3.25 diopters needed to achieve clear vision at 1/3 of a meter. Individuals who do not require distance correction only require lenses that correct the presbyopia. For individuals who require distance correction, bifocal lenses may be the solution, or trifocal and multifocal if they require distance, intermediate distance and near correction.

Astigmatism is an optical condition in which the refracting power of a lens or a cornea is not the same in all meridians, which produces an image with multiple focal points or lines (see Fig. 1-6). Astigmatism can occur by itself or in conjunction with myopia or hyperopia.

Fig. 1-6. Astigmatism prod uces an image with multiple focal points or lines on the retina (Courtesy of Laser Sight Centres).

8 The anterior corneal surface in an emmetropic person is spherical, but it is flatter peripherally giving the cornea a hydrobolic shape. In regular astigmatism there are two principal meridians with constant power and orientation across the papillary aperture, resulting in two focal lines. The astigmatism is then further defined according to the position of these focal lines with respect to the retina as shown below (see Fig. 1-7): • simple myopic is when the other meridian is anterior to the retina • simple hyperopic is when the other meridian is intercepted by the retina before coming to focus • compound myopic astigmatism is when both meridians are anterior to the retina • compound hyperopic astigmatism is when both meridians are intercepted by the retina before coming to a focus • mixed astigmatism is when one focal line is focused in front of the retina and the other focal line is intercepted by the retina

Fig. 1-7. Types of regular astigmatism as determined by the positions of the two focal lines with respect to the retina (Vaughan, Asbury and Riordan-Eva). 3

When the principal meridians are at right angles and their axes lie within 20º of the horizontal and vertical, the astigmatism is subdivided into astigmatism with the rule , in which the greater refractive power is in the vertical meridian. Conversely, astigmatism against the rule occurs when the greater refractive power is in the horizontal meridian. Oblique astigmatism is regular astigmatism in which the principal meridians do not lie within 20º of the horizontal and vertical meridian (see Fig. 1-8). When light traverses a spherical lens obliquely creating an additional cylindrical lens the effect is called astigmatism of oblique incidence . In irregular

9 astigmatism the power or orientation of the principal meridians changes across the papillary aperture. This usually occurs from corneal scarring and keratoconus. 1

The lens curvature changes with age. During infancy it is more spherical, but throughout childhood and adolescence astigmatism “with the rule” develops, i.e., the vertical meridian has a shorter radius and more powerful refracting surface than the horizontal meridian. The lens becomes more spherical during middle age and develops “against the rule” astigmatism. Minor degrees of astigmatism may occur from variations in radius of curvature of the lens.

Fig. 1-8. Types of astigmatism as determined by the orientation of the principal meridians and the orientation of the correcting cylinder axis (Vaughan, Asbury and Riordan-Eva). 3

The symptoms of astigmatism vary considerably. A distinct retinal image cannot form, but the circle of least diffusion may be imaged as shown in Figure 1-9.

Fig. 1-9. The astigmatic dial as seen by a patient with astigmatism. The t hick black lines are focused on the retina, whereas the thin lines lie in front of the retina (Newell). 4

Astigmatism is neutralized by cylindrical lenses. A planocylindrical lens has one flat surface and one cylindrical surface, producing a lens with no optical power in the meridian of its axis and maximum power in the meridian 90º away from the axis meridian (see Fig. 1-10). The

1 Most technical terms necessary for understanding this thesis are defined in the text. However, the reader is encouraged to consult the Glossary as necessary for terms not thus defined.

10 total effect is the formation of a line image, parallel to the axis of the lens, from a point object. The orientation of a planocylindrical lens is specified by the meridian of its axis.

Fig. 1-10. A planocylindrical lens with axis in the horizontal meridian (Vaughan, Asbury and Riordan- Eva). 3

In a spherocylindrical lens, the cylindrical surface is curved in two meridians but not to the same extent. These principal meridians are at 90º to each other. The effect of a spherocylindrical lens on a point object is to produce a geometric figure knows as the conoid of Sturm , consisting of two focal lines separated by the interval of Sturm (see Fig. 1-11). The position of the focal lines relative to the lens is determined by the power of the two meridians and their orientation by the angle between the meridians. Cross-sections through the conoid of Sturm reveal lines at the focal lines and generally ellipses elsewhere. In one position, the cross-section will be a circle that represents the circle of least confusion , which is where refractive errors are neutralized and the best corrected visual acuity is produced.

Fig. 1-11. The conoid of Sturm, formed by light refracted by an astigmatic lens (Vaughan, Asbury and Riordan -Eva). 3

The specification of the lens power and orientation is written into a form of prescription, and then spectacles or contact lenses are made to these exact details (see Fig. 1-12).

11

Fig. 1-12. Spherocylindrical lens with the specification power and orientation is transferred into a spectacle (Courtesy of the American Academy of Ophthalmology Refractive Surgery slides 1995).

Apart from various axial lengths, corneal and lenticular curvatures causing refractive error, other physical properties of the eye are also contributing factors and can give rise to higher order aberrations.

1.2 The Cornea and Its Physical Characteristics The cornea is the transparent, avascular, dense sensory nerve system structure that forms the anterior one sixth of the globe through which the iris pattern and black pupil are normally clearly visible. It is unique among the stratified squamous epithelia of the body in that it provides an absolutely smooth, wet, apical surface that is the eye’s major refractive surface. The cornea plays an important role in absorption of topical drugs and in wound repair, but its primary function is to act as a powerful optical lens of fixed focus that transmits light in an orderly fashion for proper image formation. It was mentioned in section 1.1 that the cornea is one of the four media of refraction in the eye. With its 42-diopter refractive power, the cornea is the principal refractive tissue of the eye because it separates air, with an index of refraction of 1.0, and aqueous humor, with an index of refraction of 1.34, thus allowing the cornea to function as a lens. A film of tears provides a high-quality optical surface, and its secondary functions include lubrication during blinking and an antibacterial action mediated by lysozyme, betalysin, and leukocytes to help in wound repair (see Fig. 1-13).

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Fig. 1-13. Illustration of cornea-tear film interface (Courtesy of Alcon Australia).

The regular arrangement of the 200 corneal lamellae, the scarcity of keratocytes, the absence of blood vessels, and deturgescenece make the cornea transparent. Corneal transparency requires integrity of its entire five layers and properties.

1.2.1 Anatomy of the Cornea Traditionally, the cornea is said to be comprised of five layers: epithelium, Bowman’s membrane, stroma, Descemet’s membrane, and endothelium (see Fig. 1-14). The basement membrane of the epithelium is considered separately, since it has assumed great clinical importance.

Fig. 1-14. The five layers of the cornea with the tear film on its anterior surface, followed by the epithelium, Bowman’s membrane, the stroma, Descemet’s membrane and the endoth elium (Albert and Jakobiec). 5

Epithelium. This accounts for about one-tenth of total corneal thickness and is made up of three cell types (see Fig. 1-15): (a). The basal columnar cells from a single layer which is attached to the basement membrane (basal lamina) by hemidesmosomes. The nucleus of each basal cell is

13 displaced towards its apex. The wing cells and surface cells are derived from the basal cells. (b). The wing cells are arranged in two or three rows and have “wing-like” extensions (c). The surface cells are long and thin with flat nuclei. They are arranged in two layers and are joined by bridges. The surface area of the outermost cells is increased by microplicae and microville in order to facilitate the absorption of mucin which is essential for corneal wetting. The surface cell’s life span is a few days and it is shed into the tears. Because of its excellent ability to regenerate, the epithelium does not scar.

Fig. 1-15a. Histology of epithelium (Kanski). 6 Fig. 1-15b. Light microphotograph of the epithelium showing: (a)surface cells, (b)wing cells, (c)basal cells, (d)Bowman’s layer (Hogan, Alvarado and Weddell). 7

The basement membrane. This is considered separately, since it assumes great clinical importance. It is 480 Å thick and is separated from the basal membrane by a lucid zone. It is produced by the basal epithelial cell. Filaments extend from hemidesmosomes along the basal cell membrane to and through the basement membrane, forming firm adhesion. The basement membrane is of utmost importance in epithelial cell adhesion. When abnormal, it is associated with recurrent erosion and epithelial defects. Posteriorly, the basement membrane blends indistinctly into Bowman’s membrane (see Figure 1-16).

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Fig. 1-16. Illustration of a basal cell, its basement membrane, and Bowman’s layer. Half-desmosomes (a) are seen along the basal cell membrane, with filaments extending from them to the basement membrane (b). The basement membrane is a dark osmiophilic line which is separated from the cell membrane by a less dense zone. The collagen of Bowman’s layer (c) has a random disposition (Hogan, Alvarado and Weddell). 7

Bowman’s layer. Lying directly below the basement membrane of the epithelium is a transparent sheet of tissue known as Bowman’s layer (see Fig. 1-17). It is composed of strong layered protein fibers called collagen. This acellular structure represents the superficial layer of the corneal stroma. Once injured, it forms a scar as it heals. If the scar is large and centrally located, vision will be affected.

Fig. 1-17. Light micrograph of Bowman’s layer (a), the anterior stroma (b) and the corneal epithelium (c). There is a change in the direction of the superficial lamellae as they curve forward to merge with Bowman’s layer as shown by the arrows (Hogan, Alvarado and Weddell). 7

The stroma. This makes up 90% of the corneal thickness. It is composed of collagen- producing fibroblasts (keratocytes), collagen fibrils, and ground substance. The fibrils are of uniform size, extend across the entire length of the cornea as bundles (lamellae) which criss- cross at approximate right angles but interlace infrequently. The ground substance which occupies the space in between the lamellae is composed of mucoprotein and glycoprotein (see Fig. 1-18).

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Fig. 1-18. Corneal stroma. A, low magnification electron micrograph. The stromal collagen varies in density and has a lamellae arrangement. Dark bands are created when the stromal lamellare are cut longitudinally, lighter bands are obliquely and in cross-section. Several fibroblasts lie between the lamellae (arrows). B, higher magnification of the lamellae and cells. One lamella measuring 6um cut longitudinally (brackets). Other lamellas are sectioned obliquely (a) and in cross-section (b). C, collagen fibrils cut in longitudinal section. Four fibrils are separated by an interfibrillar space, which is occupied by granular material. The fibrils show fine striations (arrows) indicating the positions of darker striations which are separated from each other (Hogan, Alvarado and Weddell). 7

Descemet’s membrane . This is the basal lamina of the corneal endothelium. It is composed of a fine lattice-work of collagen fibrils consisting of an interior banded zone, which develops in utero, and a posterior non-banded zone which is laid down throughout life by the corneal endothelium (see Fig. 1-19).

Fig. 1-19a. The regular lattice-like structure of the collagen bundles and cross-linking elements in the anterior banded layer of Descemet’s membrane (Albert and Jakobiec). 5

16 Fig. 1-19b. Descemet’s memb rane. The thickness of Descemet’s membrane changes with increasing age. A, Eye of a year and a half old child. Light micrograph showing the endothelium (e) and a Descemet’s membrane (d), which have the same thickness. B, Eye of a 50 year old person. Descem et’s membrane (d) is more than twice the thickness of the endothelium (e) (Hogan, Alvarado and Weddell). 7

The endothelium . This consists of a single layer of hexagonal cells. It plays a vital role in maintaining the deturgescenece of the cornea, which is required for normal transmission of light by forming a barrier to the free flow of fluid from the aqueous humor to the stroma and by the activity of ionic pumps that draw the water from the stroma to the aqueous humor (see Fig. 1-20a).

Fig. 1-20a. Corneal endothelial barrier and pumping action. When the rate of fluid leakage into the stroma is balanced by the rate of fluid pumped ou t of the stroma, normal corneal architecture and thickness are maintained (Albert and Jakobiec). 5

With age, the number of endothelial cells gradually decreases, but cell size tends to increase. As the endothelium is incapable of regeneration, neighbouring cells have to spread in order to fill any gaps. If it is damaged it will be scarred permanently (see Fig. 1-20b, c).

17 Fig. 1-20b. Microscopic images of the human corneal endothelium in normal subjects showing the neatly packed hexagonal cells and that cell size tends to increase with age. (A) a 20-year-old subject – normal cell count should be around 2593 cells/mm 2; (B) a 44-year-old; (C) a 59-year- old; (D) a 69-year-old; (E) an 83-year-old subject – normal cell count should be around 2134 cells/mm 2 (Albert and Jakobiec). 5

Fig. 1-20c. Specular micrograph of the endothelium of a

human corneal graft patient. There is marked variation

in endothelial cell size and shape, and the cell borders

are more easily defined than in a normal young cornea.

Cell count of this patient is only 587 cells/mm 2, which is

markedly reduced from normal (Bron, Tripathi and

Tripathi). 8

The aim of any refractive surgery is to manipulate the refractive error by altering either the corneal curvature, the lens, or the axial length of the eyes. The history of refractive surgery is the most innovative among all the fields of ophthalmology. To appreciate the rate of evolution one must review the history and its milestones, especially over the last two decades.

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C H A P T E R 2

Refractive Surgery

Chapter 2

2.0 History of refractive surgery For the past 200 years ophthalmic surgeons have been attempting to surgically manipulate refractive errors, as outlined by Schwab. 9 In 1790 Tadini and Casannatta attempted to modify the crystalline lens of the eye. In the late 1800s, Fukala, Lans and Bates conceived and attempted corneal relaxing incisions. In 1869 Snellen attempted to alter the curvature of the cornea by making incisions in the anterior cornea. In the early nineteenth century Mueller attempted an eye shortening procedure by shortening the axial diameter via scleral resection. This procedure was abandoned with the introduction of the safer and more effective techniques of scleral buckling. In 1939 Sato began using corneal incisions, and in 1953 he effected modification of myopia by flattening corneal curvature using endothelial and epithelial incisions. Most of the patients progressed to corneal edema because of endothelial decompensation and eventually required corneal transplantation.

It was at this time that the idea of refractive lamellar surgery was born. As cited in the literature, 9,10,11 in 1949 Barraquer introduced the concept of intracorneal lenticule, the idea of carving the anterior corneal tissue to correct refractive error. This was known as “refractive keratoplasty”. Thirteen years of experimentation on animals followed, during which time he discovered the principles of many of today’s lamellar refractive surgery techniques and formulated the concept that myopia can be corrected by flattening the cornea when removing tissue from the optical centre of the cornea. Hyperopia can be corrected by steepening the cornea when adding tissue to the optical centre or removing it from the periphery. Barraquer’s experiments progressed from manual freehand corneal dissections to the design and evaluation of the prototype of a microkeratome (corneal shaper) based on the principle of the carpenter’s plane. In 1958 he published work showing success in corneal lathing techniques including Keratomileusis, keratophakia, and epikeratophakia.

Keratomileusis, devised by Barraquer, uses a microkeratome to excise a lamella of the patient’s cornea. This disc of corneal tissue is frozen on a cryolathe, ground into the desired shape to correct the refractive error, and replaced on the patient’s remaining corneal bed (see Fig. 2-1). Any error with the cryolathe in the cut of the lamellar disc could destroy the tissue.

19 If that occurs, a donor allograft (human corneal tissue) must be substituted. The procedure is conceptually brilliant, but surgically difficult. It is principally for myopia, but can be performed for aphakia. 9

Fig. 2-1. Keratomileusis. (A) The ground lamella is then sewn back onto its original bed. (B) Hyperopic keratomileusis. (C) Myopic keratomileusis (Schwab). 9

Keratophakia was also devised by Barraquer. A donor cornea is carved into a lenticule of the appropriate shape and power. This computer-designed organic lens is prepared to match and neutralise the refractive error of the recipient eye. The microkeratome is used to shave a lamella off the recipient bed. The donor lenticule is placed between the excised corneal lamella and the recipient corneal bed, then sewn in place (see Fig. 2-2).

Fig. 2-2. The procedure has two variations. (A) Facing view of the host with donor lamella sewn into place. (B) Sagittal view of the same concept. (C) Sagittal view of a variation of keratophakia in which the cornea shows an intrastromal pocket with a donor lent icule (may be alloplastic material) inserted (Schwab). 9

In 1963, Barraquer first used his microkeratome on human corneas to correct hyperopia and myopia. By then the technique included the use of a pneumatic ring that provided constant intraocular pressure for a predictable passage of the microkeratome, applanation lenses that determined resection diameter, and a cryolathe on which the corneal disc was frozen and carved. He is credited with originating this concept and many lamellar surgery techniques used today, including superficial lamellar keratectomy, intracorneal placement of a lenticule (keratophakia), the use of the hinged lamellar flap for in situ resection, the technique which

20 was coined by Ruiz as automated lamellar keratoplasty or ALK (the same technique LASIK surgeons use today), and lamellar resection with controlled ectasia for hyperopia.

Epikeratophakia was conceived by Werblin and Kaufman in 1979. A lenticule is prepared from a donor cornea, lyophillized, and stored like an intraocular lens. The surgeon removes the epithelium from the host cornea and trephines a superficial, midperipheral, circumferential sulcus. The appropriate power donor lenticule is selected and applied to the host cornea with the edge of the lenticule fitting into the sulcus. The graft is sewn onto the front surface (see Fig. 2-3). This procedure holds the greatest promise for paediatric aphakia, but has not been convincingly shown to be superior to other forms of correction for this refractive problem. Epikeratophakia has also been used to treat keratoconus and high myopia.

Fig. 2-3. Epikeratophakia can be done for myopia or aphakia. (A) Facing view of the cornea with an epikeratophakia lenticule in place. (B) Hyperopic (aphakic) epikeratophakia. (C) Myopic epikeratophakia (Schwab). 9

Barraquer performed numerous successful keratomileusis procedures and formally taught his techniques to others in 1977. However, most surgeons abandoned keratomileusis because of its complexity, the long training period, corneal damage from freezing, frequent complications, and unpredictable results. To simplify the procedure, Krumeich and Swinger modified Barraquer’s concepts and instrumentation to produce a “nonfreeze system”. Instead of freezing the corneal cap to achieve rigidity for lathe cutting, they created a new instrument called the artificial anterior chamber cutting bench set of the Barraquer-Krumeich-Swinger to fashion the two donor lenticules. Despite these improved results, keratomileusis was still being performed by a few surgeons.

In 1986, Ruiz 11,12,13 reported more predictable results and faster patient recovery with a keratomileusis in-situ by removal of tissue from the stromal bed instead of from the corneal cap. An automated microkeratome was necessary to reduce the incidence of intraoperative and

21 postoperative problems and frequent irregular astigmatism. In late 1980s Ruiz accomplished the development of the automated geared microkeratome, which led to the use of the term ALK.9

All these refractive surgical procedures share several common problems. There is technical limitation in achieving the desired excision or incision, they are difficult to perform, and long term healing process is unpredictable. While these problems were being addressed, and during the search for a better surgical device to use as a second refractive resection to reduce refractive power that can be applied directly onto the stromal bed after keratomileusis to provide greater precision of outcome, radial keratotomy (RK) emerged and was popularized.

RK is a procedure consisting of 4 to 16 (or more) radial incisions in the cornea extending from an incision-free central optical zone to the limbus. These incisions through 80–90% of the stromal thickness are performed in order to flatten the cornea, and in turn reduce the myopic refractive error (see Fig. 2-4).

Fig. 2-4a. Histological incision depth of 90% Fig. 2-4b. RK with 8 radial incisions and 2 T-incisions following RK (Schwab). 9 (Machet). 11

RK was described by European and American surgeons in the late 1800s, but it was first developed clinically in 1936 by Sato, who built upon the principles outlined by Lans nearly half a century earlier.9,14 Sato did pioneering work in 1939 in RK for myopia. In this he made up to 40 posterior corneal incisions. Although he initially reported good results, Japanese ophthalmologists discovered years after Sato’s death in 1960 that many of his patients developed late corneal decompensation and bullous keratopathy because of endothelial damage, many eventually requiring corneal transplants.

22 Despite these poor results, Russian ophthalmologists heard of Sato’s work and began investigating its potential. Fyodorov 9,14 realized that Sato’s posterior incisions were technically difficult and concentrated on achieving his refractive goals with fewer, anterior-only incisions. Yenaliev, Fyodorov and Durnev revived and refined Sato’s techniques in the 1970s and were performing RK on a large scale by the mid 1970s, then in the late 1970s they published reports of success in treating low myopia. One year post-operatively, 84% of Fyodorov’s 565 patients had uncorrected vision of 20/50 or better. 8,15

Bores 8 learnt about RK while visiting Fyodorov in 1976. Despite his nervousness about trying the procedure in United States, Bores finally performed the first American RK in November 1978. He faced a fierce storm of criticism and rebuke for performing what everyone thought to be the dangerous “Sato Procedure”, but soon others followed.

As the popularity of RK grew in the early 1980s, so did concern about the procedure’s safety and efficacy. In 1982, the National Eye Institute (NEI) funded the Prospective Multicenter Evaluation of Radial Keratotomy (PERK) study. 14 Not everyone was supportive of the study. Initiation of the PERK study had alerted the public to the fact that the NEI and others considered the procedure investigational, even experimental. Insurance companies refused coverage for RK. Furthermore, ophthalmologists who were not investigators in the study were urged to stop doing RK until objective results from the study became available. 14

The PERK study ultimately gave RK scientific approval. Ten years of results showed that 70% of patients who had bilateral surgery needed no spectacle correction, and 85% saw 20/40 or better, although there was a progressive hyperopic shift in almost half the eyes over 10 years. 14 By 1994, when the 10 years of PERK results were reported, approximately 250,000 RK procedures were performed annually in the United States to correct lower amounts of myopia (less than -4D) with fewer, shorter incisions to reduce the chance of hyperopic shift. 14

Within the family of incisional procedure like RK there are subtypes including relaxing incisions, keratotomy incision for astigmatism, and penetrating keratoplasty.

23 Relaxing incisions were devised to alleviate high astigmatism following a corneal procedure, especially follow penetrating keratoplasty. This procedure consists of a circumferential incision usually at the graft-host junction in the meridian of the steepest axis of astigmatism post-keratoplasty. The procedure is effective but the result is difficult to predict and/or quantitate 9 (see Fig. 2-5).

Fig. 2-5. Various form of relaxing incision techniques to correct astigmatism (Schwab). 9

Keratotomy incision for astigmatism . Bates was the first ophthalmologist to attempt this procedure in 1894. Other surgeons had performed corneal incisions to control post-cataract or post-keratoplasty astigmatism. In 1979, Fyodorov and Durnev described corneal incision for myopes and thus reawakened the concept of corneal incisions for congenital astigmatism. The most commonly performed is the procedure described by Ruiz in 1983. This procedure consisted of making a trapezoidal figure with transverse (circumferential) incisions placed within two radial incisions with two intersecting points (Fig. 2-6). This procedure does indeed selectively alter the refractive state of the cornea but is difficult to quantify. 9

24 Fig. 2-6. The Ruiz procedure (Schwab). 9

Penetrating keratoplasty corneal transplantation is a refractive procedure, although it is not always thought of as one (see Fig. 2-7). Occasionally, corneal transplantation may be performed for irregular astigmatism or other refractive problems, but it frequently creates astigmatism, ametropia, anisometropia, and/or aniseikonia itself. The refractive problem is so significant that as many as 10% of patients are not satisfied post-operatively.8

Fig. 2-7a. Penetrating keratoplasty: (a) excision of Fig. 2-7b. Post-operative appearance of host tissue by trephination; (b) completion with scissors; penetrating keratoplasty (Kanski). 6 (c) suturing of donor button (Kanski). 6

However, all these refractive surgical procedures share several problems. The significant technical limitation is in achieving the exact desired excision or incision of corneal tissue. The most significant biological problem is that all the procedures result in scarring as the incision heals, thus reducing the cornea’s transparency and degrading its optical performance. Patients are especially aware of this disturbance at night when the pupil is dilated. The field of refractive surgery was renewed with interest when the laser was suggested as a surgical incision device. Refractive change was accomplished by removing tissue from the anterior surface of the cornea using laser composed of carbon dioxide in 1981. By 1986 a new

25 laser known as the excimer laser proved to be able to accurately remove and heal patterns of tissue. The number of RKs and other incisional procedures being performed in the United States and around the world reduced significantly in the early 1990s, as laser procedures such as excimer photorefractive keratectomy (PRK) and later laser-assisted in-situ keratomileusis (LASIK) gained approval as the preferred refractive procedure.

2.1 The Origin of Excimer Laser According to Gimbel and Penno, 16 scientific study of the clinical-surgical use of the excimer laser began in the 1960s at the Avco Everett Research institution and in the 1970s during experimental trials conducted by Toboada on behalf of the United States Forces. 10 By 1976, the same type of irradiation was used in engineering and electronics to perform microincisions. According to the literature, 11,16,17 the term excimer is derived from “excited dimer”, which consists of an inert gas and a halide, specifically argon (Ar) and fluoride (F) gaseous elements excited to a higher energy state by thousands of volts of electricity. 11 Dimer is a misnomer as it applies to two of the same element. When the argon and fluoride elements are premixed with a helium mixture, the combined elements form an unstable compound which in a high voltage cavity causes rapid dissociation and produces a cool (non-thermal) ultraviolet beam of light known as excimer laser. This ultraviolet light has an electromagnetic wavelength between 190 and 400 nanometers depending upon the gas element used.

It was found that the ultraviolet light energy of 193 nanometers wavelength produced the smoothest ablation effects at lower energy densities and did not exhibit mutagenic or cataractogenic behaviour. It could remove molecules of tissue with virtually no heat or damage to the surrounding tissue. More precisely, it removes 0.25 microns per pulse and damages an additional 0.25 microns of adjacent corneal tissue. This laser process was termed ‘photoablation ’, meaning vaporization through the use of laser light. Due to this capacity of excising corneal tissue with submicron precision as well as submicron collateral damage, it generated considerable interest for the innovators of refractive surgery.

In 1983, Trokel 11 performed the first corneal operations using an excimer laser, subsequently publishing the first paper describing the procedure (see Fig. 2-8). Srinivasan et al 11 coined the

26 term “photoablative decomposition”, better known today as photoablation, to describe the photochemical process by which far ultraviolet light energy produces tissue removal through the breakdown of molecular bonds.

Fig. 2-8. Excimer photoablation produces smooth tissue excision patterns with minimal disturbance to adjac ent cells (Machet). 11

In collaborative research, Trokel (ophthalmologist), Munnerlyn (physicist) and McDonald (corneal surgeon) embarked on experimentation with animals, cadaver eyes and eventually human eyes. In 1986 their findings proved that excimer PRK could safely and permanently remove and heal patterns of corneal tissue in a predictable fashion, without thermal damage to surrounding tissues. 11 It emerged that this modality allowed surgeons to alter refractive errors, eliminate post-operative corneal haze, provide long-term stability and greater predictability than any other refractive surgery technique (see Fig. 2-9).

Fig. 2-9. Drawing illustration of the principle of photoablation on the cornea. The red arrows show a pattern of corneal tissue had been photoablated centrally which in turn flatten the central corneal curvature and changed the refra ctive errors (Kanski). 6

The collaborative study of Trokel, Munnerlyn and McDonald expanded, involving a number of laser companies, to produce the accurate, reproducible software and hardware specifications required to formulate a laser delivery system as a surgical instrument. Excimer laser as a surgical device provided a major advance in refractive surgery and gave rise to refractive procedures such as PRK and LASIK.

27 2.2 Evolution of PRK In 1983 Strokel and Marshall developed the technique and known today as PRK. 10,11 The technique utilizes controlled excimer laser pulses to ablate stromal tissue, producing an excision pattern. The interaction with the cornea at the high-energy 193nm wavelength determines “photoablation”, the rupture of the molecular bonds in the targeted tissue, which is reduced to fragments little more than a few molecular weight units. This causes a sudden increase in the volume of debris in the photoablated area and its subsequent high-speed expulsion.

The original objective was to develop a surgical device which could cut corneal tissue, in the hope that the excimer laser could provide better incision depth control for RK. In the end, because the excimer laser removed tissue rather than splitting it, it was not suitable for RK but for PRK. By the mid-1980s the term “photorefractive keratectomy” was coined by Cooper Vision engineer Charles Munnerlyn, who constructed an excimer laser system which became the Visx Star laser. 14 The relationship between the refractive effect produced by the excimer laser and the depth of ablation is depicted by an algorithm formula developed by Munnerlyn et al. 11 which was based upon effecting a theoretical lenticular curve within polymethylmethacrylate (PMMA) model. Depth of ablation = (optical zone) 2 X refractive change 3

The principle of the formula is that the depth of ablation increases exponentially with the square of the optical zone size. That is, a small increase in the optical zone results in a large increase in the amount of tissue ablated for any dioptric correction, as shown in Table 2-1.11

28 Table 2-1. Depth of ablation and its corresponding optical zone size (Machet). 11

Trokel, Munnerlyn and McDonald worked together on the first PRK studies on animal and human cadaver eyes between 1984 and 1987, trying to improve the laser and the technique. 11,16 In 1985, Seiler first used the excimer laser on a blind human eye which was scheduled for exenteration. In 1988, McDonald performed the world’s first PRK on a normal sighted eye.

By the early 90s the procedure was widely used worldwide, because it was simple to perform. It is utilized to correct low to moderate myopia. The procedure involves two steps (see Fig. 2- 10): 1. The epithelium is marked with a 7.0mm Hoffer trephine centred over the pupil. De- epithelialization is performed with a blunt spatula. This process is known as mechanical debridement. 2. The excimer laser is used to ablate and remove the intended amount of surface corneal tissue, in turn reshaping the corneal curvature and correcting the refractive error. Deeper cell layers remain virtually untouched and the cornea keeps its original strength. At the end of the procedure, a therapeutic contact lens is applied onto the eye. The patient is typically seen at day 1, day 3 when the contact lens is removed, 1 week, 1 month and 3 months to monitor the re-epithelialization, to ensure that it has occurred and completed. This pattern of follow-up may vary depending on surgeon preferences and patient issues.

29

Fig. 2-10a. Blunt mechanical epithelial debridement Fig. 2-10b. The crisp light reflex indicates a good initiated along the optical zone mark (Machet) 11 debridement surface. Central alignment over the pupil is crucial during photoablation (Machet). 11

2.2.1 PRK to Correct Myopia Seiler and Wollensak 12 reported the results of one year’s follow-up, showing the average difference between the intended correction and the actual refraction to be stable. However, there were some fluctuations, with 8% showing more than 1 diopter changes. The refractive changes slowed down after 6 months but some took as long as 9 months. There was a 92% success rate of refractive predictability, but vary dependent on the range of refractive errors. There was early post-operative regression in all patients as result of corneal wound healing. The healing processes appears not to depend on sex, but is slower in older patients.12,13,18-20

Clarity of the ablated corneal area is a major concern. Several healing mechanisms start after the keratectomy. They include epithelial migration, formation of adhesion structures of the epithelium, and stromal remodelling. 12 Any of these processes can create opacity in the anterior cornea as there is transient haze in all cases. This haze may not interfere with Snellen visual acuity under normal lighting conditions. 12,13,20 Glare tests show that visual acuity under glare conditions decreases after PRK. 12,13,18,20 However, this is also observed in some eyes with clear corneas, leading some researchers to conclude that haze is not the only reason for the poor glare vision. It was speculated that it may be due to an optical zone that is smaller than the dilated pupil, which means that the peripheral cornea creates a blurred image, an effect that is described by the patient as a halo. The intensity of this ghost image decreases with time. Larger optical zones may minimize the symptom but lead to greater excision depth, which may increase the potential for corneal opacity.

30 Visual acuity and residual refractive error are two measurements used to evaluate the efficacy of the procedure. In Seiler and Wollensak’s study, 12 96% of patients post-PRK had visual acuity better than 6/12, 48% had visual acuity better than 6/6, 58% of the patients had more than 0.5 diopter residual astigmatism, and had uncorrected visual acuity better 6/6. In the report of Gimbel et al.,21 67.3% of patients post-PRK in first eyes and 73.1% in second eyes achieved an uncorrected visual acuity of 6/6 or better, and 92.5% in first eyes and 90.5% in second eyes achieved 6/12 or better. In that same study 43% of first eyes and 45.2% of second eyes were corrected to +/- 1.0 diopter of targeted correction, 73% were within 1.0 diopter of emmetropia for both eyes. Dutt et al.20 reported that 94% of patients post-PRK had uncorrected visual acuity of 6/12 or better, 83% had 6/7.5 or better, 74% had 6/6 or better. In terms of safety and vision-threatening complications, potential blinding complications were not reported. There were two main risk factors for the occurrence of corneal scarring: possibility of non-compliance with steroids and correction of high myopia. 12

Post-operative clinical problems include pain, regression, glare and night-halo effects. Others having a more profound effect are corneal haze or scarring, decreased contrast sensitivity, decentration and irregular astigmatism, and central islands. 10-18, 20--22

Pain . Immediately post-operatively there were moderate to severe levels of pain depending on the pain threshold and tolerance level of the individual patient. Patients were given and advised to take analgesics during the first 24 to 48 hours of the immediate postoperative period.

Regression . The treated eye may lose some of the effect of surgery within first few months, this being greater in high myopic corrections. The exact causes are unclear, but could include healing characteristics, early discontinuance of corticosteroid, depth of ablation, and others. 12,13,18,20 In one survey of 182 patients it was found that regression was the major cause of patient dissatisfaction after PRK. 18

Glare . Immediately post-operatively, like pain, there were mild to severe levels of glare depending on the glare threshold and tolerance level of the individual patient. Patients were

31 advised to wear sunglasses when appropriate for 6 months, not only to protect the eye from the brightness but also minimize haze formation due to UV radiation on the wound while healing.

Night halo effects . A halo effect around lights at night was noticed, particularly by patients with large pupils (see Fig. 2-11). This effect decreases after the first few months, and it should be reduced considerably by the use of larger ablation zones where possible.

Fig. 2-11. Halos (American Academy of Ophthalmology Refractive Surgery slides 1995).

Symptoms such as “starburst”, “halos” and “blur” are all part of a subjective quality of vision assessment, and are associated with night vision only. Researchers 11,12,13,18,20 have suggested that these night vision phenomena increase in incidence with decentred and small optical zones. However, only a rough correlation has been found between pupil size, optical zones and night vision effects. In other words, some patients who had large pupils did not have significant complaints, and others who appeared to have relatively small pupils had significant complaints. Three factors may affect the accuracy of assessing these night vision phenomena: 1. There are variations in accurately measuring pupil size. The only reliable method for measuring pupil size is in darkness or near-total darkness with an instrument such as an infrared camera or a similar device that does not stimulate a pupil response. One such instrument is known as the Colvard Pupillometer, designed by Dr Michael Colvard (USA), manufactured by Oasis Medical and released in 1998 (see Fig. 2-12). It is now widely used to ensure that the patient’s pupil size is accounted for when planning a treatment profile.

32 Fig. 2 -12. Colvard Pupillometer. Courtesy of the Colvard Pupillometer website www.revoptom.com/PS/Colva.htm

2. Night vision phenomena are often difficult to assess accurately, because patient responses are entirely subjective. Often there is great difficulty in communicating exactly the difference between these symptoms; rarely does one encounter a patient with sufficient artistic skills to draw the exact patterns experienced. 3. It is difficult to quantify the severity of the effect. There are great variances in patients’ ability to tolerate certain visual aberrations.

The “starburst” and “halo” effect could potentially come from three sources: 1. Residual refractive error. This would give rise to a blurry circle or “shadow”, which some patients might interpret as a “starburst”. 2. Edge effect. This would consist of light scatter from the edge of the optical zone (see Fig. 2-13).

Fig. 2-13a. Daytime conditions with a small pupil Fig. 2-13b. Demonstration of the edge effect showing no light scatter or optical aberration causing variable scatter of light rays which strike (Serdarevic). 22 the cornea at the edge of the optical zone when pupil dilates at night (Serdarevic).22

33 3. Peripheral myopia, with pupils that dilate beyond the optical zone. This may produce a separate myopic focus from the untreated peripheral cornea, which would create a larger, blurry circular image or halo around the primary image. Despite the rough correlation between pupil size and night vision phenomena, research 22 has generated some impression of the incidence for various optical zones: 4.5mm creates night vision disturbance phenomena in 20% of patients, 5.0mm creates such phenomena in 12% of patients, 6.0mm creates such phenomena in 5% of patients, and 6.5mm with a transition zone of 8 or 9mm creates such phenomena in 0% of patients.

Corneal haze or scarring . A variable amount of anterior corneal haze is detected on slit lamp examination during the first month after treatment, which may or may not fade over the first year (see Fig. 2-14). The incidence and severity of this haze increases as higher degrees of myopia are treated.

Fig. 2-14. Diffuse confluent corneal haze centrally following PRK for moderately severe myopia correction (Machet). 11

Decreased contrast sensitivity . Statistically significant decreases in contrast sensitivity have been found at all frequencies in both dilated and undilated pupils, except at the highest frequency in the dilate state. Contrast sensitivity reached its lowest levels in the dilated state. 19 This may contribute to complaints about worse vision at night. However, some degrees of these subjective visual complaints are also presented pre-operatively. Therefore it is uncertain as to whether such subjective symptoms are caused by PRK.

Decentration and irregular astigmatism . A small percentage of decentration has been reported, causing irregular astigmatism.13 However, this could be minimized with a better

34 laser guidance system, better instruction of patients in fixation during ablation, and better surgical technique (see Fig. 2-15).

Fig. 2-15. Topography showing superior- temporal decentration ablation (area coloured in blue) (Machet). 11

Central islands . A central or pericentral steepening of corneal curvature has been found in post-PRK patients (see Fig. 2-16). The existence of a central island was the most significant topographical abnormality observed in both incidence of diagnosis and clinical symptoms experienced by patients who underwent PRK. 11 It was associated with clinical symptoms of monocular diplopia, ghosting of images, and significant visual disturbances. It was most notable when a broad beam excimer laser was used.

Fig. 2-16. Central island formation following PRK (Machet). 11

Many theories have been proposed to explain central islands, including that they are a transient anomaly, or a focal epithelial hyperplasia, explanation by vortex plume theory (suggesting that the emitted plume of ablative debris forms a random vortex centrally blocking successive pulses), and degradation of beam optics centrally resulting in a less ablative effect. The theories that seem to have gained acceptance are the acoustic shockwave model and the differential hydration model by Lin.11 Both theories are centred around hydration as the key element, and both are likely to play a role (see Fig. 2-17).

35 Fig. 2-17. Schematic illustration shows energy beam profile pr oducing acoustic shockwaves determine intraoperative hydration pattern creating central fluid accumulation (Machet). 11

As well as post-operative clinical problems which are verifiable to varying degrees, subjective complaints have been reported. These include patient intraoperative and postoperative discomfort, delay in post-operative recovery, delay in visual rehabilitation, prolonged use of post-operative medication, use of topical steroid eye drops, dry eyes, foreign body sensation, and susceptiveness to infection. 11 In summary, the general consensus among surgeons is that PRK is predictable and effective to correct refractive errors under -6.00 diopters, but by the end of the 1990s most surgeons had reduced their preference to -4.00 diopters with minimal astigmatism. Munnerlyn and others have demonstrated that other procedures should be explored for eyes with higher refractive error, due to a loss of corneal transparency secondary to stromal scarring with deeper ablations. Correction of refractive errors greater than -6.00D has resulted in an increased incidence of clinical significant haze, myopic regression, and loss of best corrected visual acuity. 11-13,16,18-21,29 Of equal clinical significance, the smaller optical zones produce significant night glare, which introduces the concept of qualitative vision as an essential aspect to consider beyond merely quantitative vision as measured by visual acuity. According to Machet, 11 researchers have tried to develop techniques using larger and multi-optical zones treat larger refractive errors. Such techniques have two primary benefits: reduced night glare and reduced regression effect, leading to more stable results for high myopia.

2.2.2 The Multizone Technique Piovella and Dossi 11 developed the multizone technique which limits the depth of ablation while providing a larger optical zone. In this approach, high myopic correction is divided into

36 three steps with equal thirds of the total correction performed at 4, 5, and 6mm optical zones. Since only part of the treatment is performed at the largest optical zone, the overall depth is significantly reduced. Machet and Mihai Pop developed a similar technique, 11 to provide a more aspheric wound contour, to improve blending of the zones, achieve a smoother ablative surface, and to reduce ablation depth, thereby reducing haze formation while maximizing the optical zone. The multizone technique also reduces central island formation as each zone starts centrally, improving the treatment effect achieved centrally as illustrated below. TABLE 2-211

MULTIZONE TREATMENT PLAN WITH INTENDED TREATMENT -10.00D Treatment Correction Percentage of Zone diameter Tissue removed (sph) treatment (mm) (um) Zone I -5.00D 50% 4.0 mm 31 um Zone II -3.00D 30% 5.0 mm 30 um Zone III -2.00D 20% 6.0 mm 30 um Blend zone 0.00D 0% 7.0 mm 0.0 um Total -10.00D 100% 6.0mm treatment zone 91 um with 1mm blend zone

2.2.3 PRK to Correct Hyperopia The treatment of hyperopia, and especially presbyopia, represents a fundamental challenge. The biomorphological and biomechanical corneal structure and architecture seem to engender greater difficulty compared to the treatment of myopia. In 1991 Dausch, Klein and Anschutz 23,24 began to correct hyperopia with the excimer laser. The principle is to steepen the anterior cornea by recontouring the cornea to a convex-like lens, which is achieved with a furrow like ring zone in the corneal periphery. To sculpt such a ring zone, a larger ablation zone than in myopic PRK is required. An eye mask with spiral aperture is used along with a special suction ring placed on the eye for fixation. The laser works with the scanning-slit technique aligned through this rotating spiral mask profiling a 7mm length and 1mm width, ablating an annular deepening of the peripheral cornea without ablation of the central cornea. 24 The overlap scanning process ensures that the ablation produces smooth surfaces. The diameter of the corrected zone is 4mm, but the overall diameter including a transition zone is 7mm with a 1.5mm transition zone ring on all sides (see Fig. 2-18).

37

Fig. 2-18a. Scanning technique for ablation of large Fig. 2-18b. Ablation principle and cross-section areas (Salz et al.). 15 profile of correcting -10D (Salz et al.). 15

Fig. 2-18c Eye mask with spiral aperture to correct Fig. 2-18d. Suction ring placed on the eye. The hyperopia (Salz et al.). 15 mask is then inserted into this ring (Salz et al.). 15

Dausch et al. 23 found that at one year follow-up, 80% of eyes were within +/- 1.0 diopter of the intended correction, which ranged from +2.0 to +7.50 diopters with visual acuity of 20/40 or better. Only 37% of eyes were within +/-1.0 diopter of the intended correction for eyes greater than +7.50 diopters. The authors concluded that PRK is an efficient, relatively safe and predictable procedure for correction up to +7.50 diopters. By the late 1990s, even with the scanning laser ablation profile, most surgeons agreed that hyperopic correction up to +5.00 diopters was considered the upper limit. Beyond this range of refractive error patients have a higher risk of losing three or more lines of best-corrected visual acuity.

For PRK to correct hyperopia, intraoperative and postoperative complications include • Decentration of the clear zone or ablation area. A slight decentration may lead to astigmatism and loss of best corrected visual acuity. A small optical zone (4mm) and small aperture of the spiral mask make centration more difficult. • The rates of under-correction and regression are higher than those for myopia. • Slow rehabilitation, with a slow return of best corrected visual acuity.

38 • There may be a ring haze which is dense at the border of the ablation, more so with higher correction. • Problems with glare. • Higher correction causing greater decrease of visual acuity, possibly due to the clear zone being smaller than the dilated pupil.

2.2.4 PRK to Correct Astigmatism or Combined Myopia-Astigmatism PRK is capable of correcting myopia-astigmatism by using an erodible mask and ablatable polymethylmethacrylate (PMMA) mask to control corneal shape and to transfer a spherical or toric curve to the cornea (see Fig. 2-19). The ablatable mask is a thin PMMA lens supported by a quartz substrate. Its power is individualized for the eye’s spherical or toric refractive correction. The mask is applied to the patient’s eye by a manually held disposable eye cup that contacts the sclera. Humidified air is delivered during the procedure and the effluent arising from the PMMA and corneal ablation is removed from the eye cup using an integrated suction tube. The mask is ablated at the same rate as the cornea. After ablation is completed, the optical shape of the mask is transferred to the corneal surface. 25,26

Fig. 2-19a. An ablatable mask laser delivery system Fig. 2-19b Eye cup containing ablatable mask (Casebeer and Slade). 10 is positioned on the patient’s eye (Harch and Petal). 26

Advantages of the use of PRK to correct myopia-astigmatism include 25,26 : • It can transfer almost any shape onto the corneal surface. • The corneal surface is smoother. • It produces less haze.

39 • It is easier for eye fixation and a controlled humidified environment over ablation zone. • It achieves better spherical correction.

Disadvantages include 25,26 : • Cylinder correction may be limited. • Some long-term epithelial abnormalities may lead to regression. • There may be difficulty aligning the mask over the cornea and entering the treatment. Future development is underway to improve alignment of the mask over the eye. • Glare and halos are a significant problem in some cases. • There is some degree of under-correction.

2.2.5 PRK to Correct Astigmatism or Combined Hyperopia–Astigmatism Dausch et al. 23 began to correct hyperopia-astigmatism in 1993. They used the rotating hyperopic template with a 9.0mm ablation zone and a 6.0mm optical zone (see Fig. 2-20). The approach is to perform an oval furrow-like ring-zone ablation in the steep meridian. Unequal angle steps and angle distances develop because of differences in rotation speed. There are various ablation depths during the rotation in each desired meridian, which are intensified peripherally. These rotating templates are good for correcting cylindrical error in combination with a spherical part. The correction of simple cylinders with a steepening of only one meridian and with no change of the orthogonal meridian requires longer ablation profiles.

40

Fig. 2-20a. Rotating hyperopic template, with a Fig. 2-20b. Computer simulation of compound hyperopic 6mm optical zone and a 9.0mm ablating zone astigmatic correction, before (top), after (bottom) treatment (Salz et al.). 15 (Salz et al.). 15

Dausch et al. 23 reported that at nine months follow-up there was a good stability with a 1.0 diopter cylindrical refraction, although success of results decreased as the refractive error increased. Complications included under-correction, higher regression (probably a biological response to the smaller ablation zone). The centration problem was worse with higher refractive error, and there were more complications compared to PRK for myopia. The authors suggested that these results could be improved with larger ablation optical zones, and further improvement could be achieved through a better aspherical profile of the central optical zone. It was recommended that use of the procedure should be limited to low degrees of refractive error.

In summary, the PRK procedure has some limitations, such that it can treat only limited ranges of refractive error effectively, and it has number of unwanted post-operative signs and symptoms. These limitations motivated innovators to further refine the art of using the excimer laser as a surgical device. With more sophisticated laser delivery systems and better ablation profiles, all the cumbersome masks and templates became obsolete, and gave rise to the procedure known as LASIK.

2.3 LASIK LASIK was initially developed by Pallikaris. 11,15,16 In 1988, Pallikaris and colleagues carried out their initial study on rabbit eyes. By 1989, Pallikaris had performed the procedure on a blind human eye, and he began studies on sighted human eyes in 1991. Burratto performed

41 LASIK on a sighted human eye in 1989 but did not publish his results until 1992. Pallikaris significantly advanced the technique by avoiding a complete corneal cap resection, instead leaving the cornea attached by a flap or hinge after the microkeratome pass. Also, he coined the term LASIK as an acronym for “laser-assisted in-situ keratomileusis”. The combination of a mechanically advanced microkeratome and excimer laser keratomileusis in situ technique under a flap was first utilized by Slade in 1993. Further developments of the technique have been carried out by Brint, Ruiz, and Salah et al. 15

The primary limitation of PRK is wound healing, which restricts the range of refractive error that can be treated and causes less desirable visual results to be achieved. The higher the degree of myopia treated, the greater the depth of ablation and the greater the healing response induced postoperatively. LASIK reduces this limitation by performing the ablation within the relatively inert stromal bed, which dramatically improves visual rehabilitation and reduces both postoperative pain and susceptibility to infection, while virtually eliminating stromal haze formation. The biggest advantage of LASIK is the complete respect for Bowman’s membrane in the visual axis, although Bowman’s membrane is transected at the periphery to create a corneal flap. The fact that it remains intact facilitates a lower degree of histological reactivity, uneventful post-surgical healing, and an absence of haze. Even the epithelial layer is spared, thus avoiding the consequent repair process and any hyperplasia in the immediate post- operative period. The reduced keratocyte reactivity also means a lower tendency to regression, linked for the most part to an attempt to restore the ablated tissue. Overall, the entire healing process would appear to be faster, with a lower incidence of the reactive phenomena than found with PRK.

However, LASIK is associated with a new set of limitations, primarily those associated with the creation of the corneal flap. The surgeon’s experience plays a major role, as he or she must undergo a suitable training period in the use of microkeratomes and corneal surgery in general. To master the “theoretical-practical learning curve” is essential. The surgeon must have detailed knowledge of the microkeratome, how to assemble it, dismantle it, clean it, and how it works, etc. Compared to surface ablation techniques, this procedure requires intensive and constant practice so that the surgeon grows in confidence with the equipment and the procedure. 27,28 All the steps of the procedure, even if minimal, play an important role in the

42 surgical result and the final refractive outcome. It requires greater technical and surgical skill, in that it represents a more complex procedure. The parameters of performing photoablation within the stromal bed, in turn alter the refractive properties of the cornea, and therefore factors such as altered mid-stromal wound healing, greater mid-stromal hydration, and proximity to the endothelium must be carefully considered.

LASIK is a procedure that combines well-established lamellar surgical techniques practised for more than three decades with the precision of PRK (see Fig. 2-21). There are two parts to this procedure: 1. Step one is known as automated lamellar keratoplasty (ALK), a microkeratome is used to create a hinged corneal flap, the flap is folded back revealing the stromal bed. 2. Step two is PRK, in which the excimer laser is used to precisely reshape the stromal layer of the corneal tissue. The flap is then returned to its original position on a cushion of balanced salt solution, and left to seal back in place.

Fig. 2-21a. The cornea with good exposure, a clear Fig. 2-21b. An A.C.S. microkeratome is being driven mark, and ready for keratectomy (Machat). 11 across the cornea to create the flap (Machat). 11

Fig. 2-21c. The second resection with excimer laser Fig. 2-21d. The flap is returned to its original position (Machat). 11 (Machat). 11

43 In 1996 Machat 11 reported a series of results as outlined in Table 2-3: TABLE 2-311 Refractive error in diopter (D) UCVA of 20/40 UCVA of 20/25 Below -3.00D 100% 64% Recruited from patients requiring enhancement from previous LASIK procedure -3.10 to -6.00D 94% 55% This group is considered to be highly effective -6.10 to -9.00D 78% 42% For this group LASIK provides not only rapid visual rehabilitation but more stable results -9.00 to -15.00D 65% 22% This group presents new challenges, and the influence of stromal hydration increases in direct proportion to the attempted correction. More patients required enhancement. Note: time period not reported in source.

According to Machat, “LASIK is one of the fastest evolving refractive procedures with such dramatic improvement in such a short span of time. With technology and techniques still improving, better results are expected. All procedures have limitations, risks, and to recognize these limitations and risks is the first and last principle of refractive surgery.” 11

In 1997 Lindstrom 29 reported similar findings and even better results, as outlined in Table 2-4: TABLE 2-429 6-month results for -1 to -10.00D, a series of 202 myopic patients operated at 12 centres Clinical outcomes Percentage (%) UCVA of 20/40 93% UCVA of 20/25 84% UCVA of 20/20 68% Residual refractive error of + 1.00D 95% Lost > 2 lines of BCVA 1.5%

44 The results in a higher myopic series of 21 patients from -10 to -30 diopters were not as good but were still better compared to other procedures, as outlined in Table 2-5.29 TABLE 2-529 Comparison of Results (% of eyes) Low myopia RK, 1 year PRK, 1 year LASIK, 6 months (-1.00 to -3.75D) Lindstrom N=47 Lindstrom N=28 Multicenter N=123 Visual acuity > 20/20 76 73 78 Visual acuity > 20/25 88 91 87 Visual acuity > 20/40 100 100 93 Residual refractive error + 1.00D 100 97 98 Loss of 2 or more lines of BCVA 0 0 0 Best-corrected visual acuity < 20/40 0 0 0 Moderate myopia RK, 6 months PRK, 1 year LASIK, 1 year (-4.00 to -6.00D) Lindstrom N=177 Multicenter N=97 Linstrom N=61 Visual acuity > 20/20 71 41 73 Visual acuity > 20/25 85 62 85 Visual acuity > 20/40 92 77 99 Residual refractive error + 1.00D 96 72 92 Loss of 2 or more lines of BCVA 0.6 5.2 0.5 Best-corrected visual acuity < 20/40 0 0 0 High myopia RK PRK, 1 year LASIK, 1 year (-6.25 to -10.00D) Linstrom N=95 Multicenter N=25 Visual acuity > 20/20 - 39 48 Visual acuity > 20/25 - 54 76 Visual acuity > 20/40 - 86 96 Residual refractive error + 1.00D - 79 88 Loss of 2 or more lines of BCVA - 6 4 Best-corrected visual acuity < 20/40 - 0 0 Extreme myopia RK PRK, 1 year LASIK, 6 months (-10.25 to -30.00D) Linstrom et al N=148 Multicenter N=21

45 TABLE 2-529 continue Comparison of Results (% of eyes) Visual acuity > 20/20 - - 10 Visual acuity > 20/25 - - 24 Visual acuity > 20/40 - 52 52 Residual refractive error + 1.00D - 54 52 Loss of 2 or more lines of BCVA - 13.5 4.8 Best-corrected visual acuity < 20/40 - 10 0

In August 1998, Argento et al. 30 reported results from 203 hyperopic patients. In that study the patients were divided into three groups: (A) less than 2.00 diopters hyperopes; (B) between 2 and 3 diopters; (C) more than 3 diopters. The authors noted there was a general trend towards either overcorrection or mild regression in the intermediate post-operative period. In most cases, this tendency was proportional to the amount of pre-operative hyperopia, and a progressive improvement in uncorrected visual acuity (UCVA) occurred between 1 and 6 months. The 6 months results are outlined in Table 2-6: TABLE 2-630 Group A (< 2D) Group B (2 to 3D) Group C (> 3D) N=138 N=153 N=170 UCVA > 20/40 94.1% 100% 87.8% UCVA > 20/20 70.3% 75.0% 45.3% Residual refractive error + 1.00D 100% 95.3% 71.4% Gained 1 or more lines of BCVA 32.7% 12% 5.8%

Most patients retained their pre-operative best-corrected visual acuity (BCVA). The greatest gain occurred in Group A and the greatest loss in Group C. Argento et al. 30 concluded that LASIK was the safest, most predictable technique for low to moderate hyperopia, even providing acceptable results in some cases of high hyperopia. Maintaining lines of visual acuity has a direct relationship to the surgical technique used. Perfect centration and the optimal optical zone used are the keys to improving night vision disturbance. The authors reported that the complications faced by surgeons were flap complications, emphasizing that

46 to significantly lower the rate of intraoperative complications no safety measures should be ignored: careful cleaning procedures, and observing the microkeratome passage under the microscope prior to performing the actual surgery.

Today’s refined techniques, technologies and instruments have made the LASIK procedure safer and more popular than any other refractive procedure. To-date according to the American Society of Cataract and Refractive Surgery LASIK Institute website [email protected] dated October 2002 it stated, “Between 1996 and 2001, over four million people had LASIK surgery in the United States. Unfortunately there were no worldwide figures.” LASIK is considered to be very effective and can correct severe and extreme myopia. It significantly increases the predictability and stability of the procedure and reduces recovery time. There is minimal pain, minimal scarring, and elimination of the process of wound healing secondary to epithelial-anterior stroma interaction. This was thought to be the main cause of the anterior corneal opacification and refractive instability of PRK. LASIK provides the capability of a combined spherical and cylindrical ablation, almost completely eliminates irregular corneal astigmatism, and decreases many procedural risks. 15,31,32 Although its original purpose was to correct refractive errors greater than -7.00 diopter, many surgeons have used it for all ranges of refractive errors as long as the corneal pachymetry is sufficient for the amount of tissue to be removed in the treatment, and for patients with no features suggestive of keratoconus. Also, surgeons have been urged to use the optimal optical zone and to preserve the prolate (naturally spherical) corneal curvature as much as possible to ensure good visual quality post-operatively (see Fig. 2-22).

Fig. 2-22. Comparison of prolate (naturally spherical) versus oblate (le ss naturally spherical) corneal curvature (Courtesy of Laser Sight Centres).

47 2.3.1 Intra-operative Complications Associated with LASIK Several complications can occur during the procedure, and vision-threatening conditions can occur. 1. Corneal perforation due to improper assembling of the microkeratome (see Fig. 2-23). Incidence is rare but this has devastating complications. Prognosis depends on the depth of the cut and damage to other parts of the eye’s anatomy.

Fig. 2-23. Corneal perforation due to improper assembling of the microkeratome resulting in decompression of the cornea and the anterior chamber (Serdarevic). 22

2. Incomplete flap. The microkeratome is unable to complete the cut in the process of creating the flap. This complication includes incomplete flap, buttonhole, and any other descriptions of improper shape of the corneal flap (see Fig. 2-24). In all cases the microkeratome is removed, the flap is positioned back to its origin and secured. The flap is re-cut at least three months later.

Fig. 2-24a. Incomplete keratectomy (Serdarevic). 22 Fig. 2-24b. Buttonhole (Gimbel and Penno). 16

3. Attempting to create a corneal flap and ending up with a free corneal cap (see Fig. 2-25). This is due to poor assembly or poor functioning of the stop mechanism. Also flat corneas are at a higher risk of a free cap.

48 Fig. 2-25. Free cap of cornea. A 360 0 keratectomy cap is created instead of a hinged flap (Serdarevic). 22

4. Intraoperative haemorrhage due to flap decentration or superficial corneal pannus secondary to long-term contact lens wear. 5. Keratectomy with an irregular surface (see Fig. 2-26). This can be due to irregularity of the blade edge, variable progression of the microkeratome either along the guides of the ring or due to hindrances during the cutting phase by reduced eye exposure, eyelid blockage, blepharostat, or surgical drape.

Fig. 2-26. The vertical striations of cornea show keratectomy with jagged, irregular incision surface. This is unsuitable to continue to the laser ablation stage of the procedure (Serdarevic). 22

6. Decentration of ablation. This can be avoided with better surgical experience, better patient education and an improved eye tracking system. 7. Shifted flap due to unexpected eye movement, which most likely occurs as the speculum and/or drapes are being removed (see Fig. 2-27). This can also occur with severe squeeze eyelid action during the immediate post-operative stage.

Fig. 2-27a. Black arrow shows where the shift on the flap Fig. 2-27b. Black arrow shows where the shift before repositioning (Gimbel and Penno). 16 was which have resolved after repositioning (Gimbel and Penno). 16

49 8. Wrinkles and folds in flap due to improper flap alignment (see Fig. 2-28). This can also occur during the immediate post-operative stage.

Fig. 2-28. Black arrows show wrinkles of the flap located centrally (Gimbel and Penno). 16

9. Epithelial defect. This may result from corneal abrasion either as the microkeratome makes its pass or from other mechanical actions induced, from preoperative topical medications prolonged and overused, or possibly simply a predisposition of the patient’s epithelium. 10. Epithelial cells and/or debris implantation in the interface (see Fig. 2-29).

Fig. 2-29. Illustration of epithelial cell implanted and ingrowth (Gimbel and Penno). 16

11. Subconjunctival haemorrhage (see Fig. 2-30). This can occur secondary to the suction ring that is placed on the eye prior to creating the corneal flap with the microkeratome.

Fig. 2-30. Subconjunctival haemorrhage at superior nasal quadrant of the conjunctiva (Gimbel and Penno). 16

12. Poor exposure due to small orbit or small eye. Lateral canthotomy may be required to create more exposure, or the problem can be avoided altogether with better patient selection.

50 2.3.2 Post-operative Complications and Their Treatments/Solutions Healing complications may arise after the procedure has been completed. These are much less or not at all vision threatening. 13. Diffuse Lamellar Keratitis (DLK), also known as “Sand of the Sahara”. It appears as a diffuse white, granular, culture-negative keratitis like waves of sand, hence the nickname Sands of Sahara (see Fig. 2-31). It is confined to the interface and respects the boundaries of the flap. The exact cause is unknown, it has been suggested that DLK is an immunologic or toxic reaction of some type of contaminant in the laminar interface. Various agents have suspected, which include debris from the microkeratome blades, meibomian gland secretion, debris from the eyelid, cleaning or lubricating solution used on blades or microkeratomes, polyvidone iodine solution, heat-stable endotoxins released from sterilizer reservoir biofilms, epithelial defects during or after surgery, and a host- immune response. DLK is defined in four stages beginning with stage 1 where white granular cells are present in the periphery of the flap. Stage 2 the cells migrate centrally involve the visual axis. Stage 3 the cells becoming denser and cause permanent scarring if not appropriately treated. Finally, stage 4 it becomes severe lamellar keratitis resulting in stromal melting and permanent scarring. Stage 1 and 2 is normally treated with topical corticosteroids. However, stage 3 and 4 require lifting the flap and debridement of the infiltrates, irrigate the area and reposition the flap in addition to aggressive treatment with topical and occasionally oral corticosteroids.

Fig. 2-31. Black arrow shows area of diffuse lamellar keratitis (Courtesy of Laser Sight Centres).

Previous Next 14. Epithelial ingrowths, defects, interface debris and flap wrinkles are all dependent on surgeon experience, but less likely with experienced surgeons. They all can be removed by careful cleaning, irrigation and repositioning of the flap (see Fig. 2-32).

51 Previous Next Fig. 2-32a. Epithelial ingrowths at late postoperative Fig. 2-32b. Wrinkles of the flap at day 1 post-op phase (Courtesy of Laser Sight Centres). (Courtesy of Laser Sight Centres).

15. Small amounts of under- or overcorrection of the sphere or astigmatism can occur, but they can be minimized with better pre-operative objective and subjective refraction and better calculation of ablation. 16. Regression. High myopia, hyperopia and high astigmatism are more prone to regression. Patients who fall into these categories should be counselled preoperatively that they have a higher likelihood of needing a post-operative enhancement when the healing process has been stabilized. 17. Decentration ablation causes asymmetry of the optical zone and diameter of the ablated area, and as a result causes a decrease in best corrected visual acuity, visual aberrations and night vision disturbances. Mild cases can be improved by re-treatment with a larger optical zone. More severe cases will require newer technologies and software such as topolink or customized wavefront ablation re-treatment. Any further treatment will require careful consideration, especially in view of the residual corneal pachymetry, to avoid ectasia (iatrogenic keratoconus). 18. Decreased dim light or night vision, characterized by symptoms such as glare, halos and starbursts that are seen around objects under dim light conditions or at night. No major study has cited the incidence of such symptoms, and there is some debate about how often they occur. As with PRK, researchers have speculated that wide pupils may venture outside the treatment area to the non-treated area. As in the case of PRK, not everyone with wide pupils experiences these symptoms and it is impossible to determine in advance who will experience them. It is best to provide all patients, especially those with large pupils, with the largest optical zone possible, as a means of prevention.

52 19. Dry eye. There was debate as to how often such symptoms occur and the cause(s) of post- LASIK dry eye during the 1999 joint meeting of the American Academy of Ophthalmology and the Pan-American Association of Ophthalmology. Battat et al. 33 suggested that tear secretion had decreased, probably due to a decrease in corneal sensitivity post-LASIK. Nevertheless, tear film stability is unaltered. Matsui et al. 34 suggested transection of the corneal nerve in creation of the flap as a cause, which explains a significant decrease in corneal sensitivity in the LASIK group compared to the PRK group, especially up to 3 months post-operatively. Surgeons were urged to give all LASIK patients a thorough pre-operative dry eye assessment such as identify amount punctuate staining using Cobalt blue light with Fluorescein sodium, and/or Schirmers Tear Test to document the amount of tear secretion as it is crucial to identify any pre-existing dry eye or suspicion of the condition and treat it prior to having LASIK, as a means of prevention (see Fig. 2-33).

Fig. 2-33a. Cobalt blue light shows fluorescein staining Fig. 2-33b. Schirmers Tear Test to assess amount of the severity of dryness (Courtesy of Laser Sight Centres). tear secretion (Courtesy of Laser Sight Centres).

The majority of the intraoperative complications mentioned were associated with the surgical technique of creating the corneal flap and/or handling of the corneal flap. The competence of surgeons improves with experience and with better keratome technology. Both the CRS-USA LASIK study 27 and Lin & Maloney 28 have recommended that a surgeon is required to perform 100 procedures, or have 3 months experience, to complete the necessary learning curve. Furthermore, to stay fluent with the surgical technique and to remain in touch with its evolution, a surgeon should practise the procedure regularly.

In 1996 the “down-up” technique, a lamellar cut from inferior to superior direction of the cornea creating a superior hinge, rather than a nasal hinge as with the older version of microkeratome (ACS), was proposed by Lucio Buratto, giving rise to the design of the

53 Hansatome microkeratome (see Fig. 2-34). The Hansatome allows more physiological attachment of the flap to the underlying stromal bed. The flap is positioned in a more natural position and in harmony with blinking movements. The time required for the healing process and stabilization is reduced compared with the ACS. The Hansatome also comes with a built- in system to prevent pseudo-suction or suction interruption during creation of the corneal flap. It significantly increases safety as well as providing greater simplicity of use and increasing the speed of the procedure. This further reduces flap complications, produces more rapid recovery and a better post-surgical period qualitatively.

Fig. 2-34a. Hansatome microkeratome (Courtesy Fig. 2-34b. 9.5mm superior hinge corneal flap being of Bausch and Lomb Surgical). created (Courtesy of Bausch and Lomb Surgical).

2.4 Beyond LASIK While LASIK continued enjoying popularity, innovators were advancing and revising to further perfect laser refractive procedures. One of these was revival of the PRK procedure, which was unveiled in 1999.

2.4.1 Laser Epithelial Keratomileusis (LASEK) Lee et al. 35 cited Massimo Camellin first introduced the concept of Laser epithelial keratomileusis (LASEK) in Ocular Surgery News, International in March 1999. LASEK is a modification of PRK where the epithelial layer of the cornea is gently separated and rolled away from the underlying stroma prior to the laser ablation and then placed back into position. LASEK therefore resembles PRK but differs in the way the epithelial cells are removed. Instead of de-epithelialization performed with a blunt spatula as in PRK, in the LASEK procedure requires the following steps (see Fig. 2-35):

54 • Preincision of the corneal epithelium is performed with a special microtrephine with a hinge at about 80º at the 12 o’clock position, 8.0 to 9.0mm in diameter, and a 70µm deep calibrated blade (Janach, J 2900S) (Como, Italy). • 20% alcohol solution is applied within the trephine diameter of the cornea for 30 seconds. • The alcohol solution is soaked up with a spear, the trephine removed, and the cornea irrigated with a balanced salt solution. • The precut margin is lifted and epithelial debridement is carried out with an epithelial microhoe (Janach, J 2915A) (Como Italy). The epithelial flap is gently separated, folded at the 12 o’ clock position, and then laser ablation proceeds as in traditional PRK. • After laser ablation, the epithelial flap is repositioned using a spatula (Janach, J 2920A) (Como Italy), and it is left to adhere to the underlying stromal bed. • A therapeutic soft contact lens is placed on the eye, which will be removed at the third day post-operatively.

Fig. 2-35a. Preincision of the corneal epithelium Fig.2-35b. 20% Alcohol solution is applied within with microtrephine (Courtesy of Laser Sight the trephine diameter of the cornea (Courtesy of Centres). Laser Sight Centres).

55

Fig. 2-35c. The alcohol solution is being soaked up Fig. 2-35d. The precut margin is being lifted and with a spear (Courtesy of Laser Sight Centres). debridement is being carried out (Courtesy of Laser Sight Centres).

Fig. 2-35e. Laser ablation proceeds as in traditional Fig. 2-35f. The epithelium is repositioned and left to adhere PRK (Courtesy of Laser Sight Centres). to the underlying stromal bed (Courtesy of Laser Sight Centres). The advantages of LASEK are that there is no need for actual cutting of the corneal flap by microkeratome, which minimizes the incidence of flap complication, the risk of infection is less because the epithelial flap acts as an effective protective barrier, there is quicker recovery, less pain, and less haze formation. The disadvantages are that it is more complex surgically compared to PRK, it is impossible to predict the success of creating an epithelial flap, there is potential difficulty in repositioning and smoothing out the thin epithelial flap at the end of the procedure, and it requires a new set of surgical instruments.

Lee et al. 35 reported results for -3.00 to -6.50 diopters correction. The eyes were randomly selected to have LASEK performed in one eye and PRK in the fellow eye by the same surgeon. Results showed during the 3-month follow-up, there was no significant difference in

56 epithelial healing time, uncorrected visual acuity and refractive error. However, the LASEK- treated eyes had significantly lower post-operative pain and corneal haze formation than the PRK-treated eyes. Among the patients, 63% preferred the LASEK procedure because of faster visual rehabilitation, almost painless recovery, and better subjective visual acuity.

Scerrati 36 reported a study where patients were equally divided into two groups and randomly assigned to either a LASIK or a LASEK group. The results showed that LASIK achieved good best-corrected visual acuity (BCVA) more quickly than LASEK, but BCVA was better in LASEK 6 months post-operatively. Analysis of corneal topographic maps showed that fewer aberrations resulted from LASEK because the surface was more regular. Furthermore, contrast sensitivity showed a substantial increase in the LASEK group compared to the LASIK group 6 months post-operatively, thus providing better quality of vision. These two studies 35,36 concluded that LASEK is a good application for treating low to moderate myopia, especially in cases of narrow palpebral fissure, limited corneal pachymetry, suspicious corneal curvature or asymmetry astigmatism. These publications dated 2001 also reported that more surgeons preferred to perform LASEK on a range of refractive errors.

2.4.2 Customized Laser Ablation In early 2000 excimer laser refractive surgery took another step forward in further evolution of the laser ablation software, making customized ablation a reality. This software facilitates correction not only of refractive errors but also of higher order aberrations – the deviation in light beams which are reflected from the retina to define the wavefront deformation (see Fig. 2-36).

Fig 2-36a. An ideal optical system focuses incoming Fig. 2-36b. Outgoing light rays from a rays with a plane wavefront where all rays converge system with aberrations have a deformed into one point at the fovea (Courtesy of Bausch and wavefront (Courtesy of Bausch and Lomb Lomb surgical). surgical).

57 This custom ablation technology takes the standard LASIK procedure one step further, such that the unique shape of every cornea as well as aberrations or imperfections naturally occurring in the eyes are measured and calculated for treatment. The aim of this form of treatment is to achieve vision better than that achieved with glasses or contact lenses, by customizing the ablation profile to treat any asymmetry or irregular corneal curvatures, which was not possible in the past.

To understand how customized laser ablation correction is achieved to reduce higher order aberration, one must understand what is higher order aberration. The concept and its complexity require a separate thesis on its own. However, to put it simply, up to the year 2000 refraction was measured based on sphere, astigmatism and axis, which is known as sphero- cylindrical refractive error of the eye. With the advent of wavefront technology, it is possible to measure global aberrations of the entire eye including higher order aberrations such as coma and spherical aberration. The concept of wavefront aberrometers is based on a couple of principles, while the Bausch & Lomb aberrometer is a wavefront aberrometer based on the Hartmann-Shack principle. A short pulse of low-intensity infrared light (780nm diode laser) is focused onto the fovea. The reflected outcoming light from the fovea is analyzed using the lenslets, which then captured by the CCD-Camera (see Fig. 2-37a).

Fig. 2-37a. The outgoing deformed wavefront is captured by the CCD- camera and the wavefront is reconstructed (Courtesy of Bausch and Lomb Surgical).

The calculated centroids – deviation of the points from their ideal position the wavefront is reconstructed, the Zywave map indicating area of higher order aberrations and the simulated patient outcome with point spread function (how a patient would see a point light source from very far away) are displayed for the surgeon to review and approve for laser ablation (see Fig. 2-37b and c).

58

Fig. 2-37b. From the measured centroids, the Fig. 2-37c. A Zywave map indicating area of higher wavefront is reconstructed (Courtesy of Bausch order aberrations and the simulated patient outcome and Lomb Surgical). (Courtesy of Bausch and Lomb Surgical).

The wavefront is then derived into various orders of Zernike polynomials – sphere, cylinder and axis is represented as 2 nd order, coma as 3 rd order, spherical aberration as 4 th order of Zernike polynomial and so on, up to the 7 th order as illustrated in Fig. 2-38. Standard LASIK treatment can eliminate only 2 nd order aberrations and visual acuity will still be limited by aberrations of 3 rd and higher orders, but customized wavefront guided ablation can detect and measure any aberration including 3 rd and higher order, then Zylink software can generate the customized ablation profile before treatment is performed, known as Zyoptix.

Fig. 2-38. Three-dimensional pictorial directory of Zernike polynom ial. Pictorial representation of each order of aberration (Macrae et al.). 37

Customized laser ablation has gone through number of modifications, such as the laser nomogram, the tracking system, and ways are still being developed to improve the process of transferring the information measured by the wavefront analyzer to the laser and then superimposing it onto the eye during treatment in order to gain the full benefit of the

59 treatment. According to experts a misalignment of 300um will cause a loss of 50% of the correction of higher order aberrations (Courtesy of Bausch and Lomb Surgical).

Chayet and Carrillo 38 have reported early results of 15 patients and found that 8% more eyes achieved UCVA of 20/25 or better with Custom LASIK. No eyes lost lines of BCVA. Time period was not reported in source.

Vongthongsri et al. 39 reported results comparing wavefront-guided customized ablation and standard LASIK and found that 100% achieved BCVA better than 20/40, and at 1 month after treatment mean high-order aberration was statistically insignificant between the two groups. According to the multi-centre Zyoptix evaluation sponsored by Bausch and Lomb, similar findings have been reported globally and there were no statistically significant differences in UCVA, BCVA, residual refractive error, contrast sensitivity, patient satisfaction with the result and their overall impression of the quality of vision between Zyoptix and Planoscan (standard) LASIK groups. However, Zyoptix removed 15 to 20% less corneal tissue than Planoscan LASIK. There was a statistically significant difference in the residual sphere, in that the Zyoptix group had less residual sphere compared to the Planoscan LASIK group. At 1 month post-treatment there was 47% chance of gaining one or more line of BCVA in the Zyoptix group compared to 27% in the standard LASIK group. At 3 months, there was 55% chance of gaining one or more line of BCVA in the Zyoptix group compared to 36% in the standard LASIK group. There was 11.5% rate of enhancement in the Zyoptix group compared to 19% in the Planoscan LASIK group. The evaluation concluded that Zyoptix provided significantly better safety and efficacy, and was capable of treating up to -12 diopters in sphere and -6 diopters in astigmatism. The system was especially effective with astigmatism. Highly aberrant eyes had significantly greater tissue preservation and larger effective optical zones. A number of variables suggested that Zyoptix was superior to Planoscan LASIK, but not enough to establish statistical significance. For these reasons, it was concluded that there was a need for a larger sample size and longer follow-up to further analyze the trends of the data and to better understand the biomechanical effects, which will be likely to continue to improve refractive outcomes and eventually reach its full potential (Courtesy of Bausch and Lomb).

60 Like many milestones of refractive surgery in the past, customized laser ablation has gone through many stages of development. It has already established number of achievements and refinements, but further improvement is needed in order to achieve its full potential and intended purpose.

All the laser refractive surgery studies mentioned above have focused on objective clinical results, but have provided little detail about subjective aspects such as patients’ perspectives of the procedure, and whether the procedure has achieved their goals and expectations. Apart from clinical evaluations, subjective impressions are also important, because patient satisfaction will ultimately influence both the future and the popularity of the procedure. More subjective evaluation is needed, to address issues such as: What is the quality of patients’ vision in the real world? How satisfied are patients in different visual functional situations? In how many and which specific areas do patients experience symptom(s) or have difficulty? Are patients likely to recommend the procedure to others?

61

C H A P T E R 3

Principle and Concepts of Patient Satisfaction

Chapter 3

Research in medical and nursing literature addressing “patient satisfaction” rose to a peak of over 1000 studies in 1994, reflecting changes in health care service and health care management, especially in the United Kingdom (U.K.) and United States of America (U.S.A.) over the past decade. 40 With the effectiveness of medical care being increasingly measured according to economic as well as clinical criteria, the inclusion of patients’ opinions in assessment of services provided has gained greater prominence over the past 25 years. Interest in patients’ opinions developed alongside the sociological interest in interpersonal relationships which demonstrated the importance of understanding the patient’s point of view. 41

In the Griffiths report cited by Sitzia and Wood 40 patient surveys were used as part of U.K. government policy as an aim to promote better health care service. McIver 42 argued that the patient satisfaction movement which grew in the wake of Griffiths report was part of a general shift towards consumerism, and is evident in all aspects of public service. Managers were encouraged to promote a “customer service-oriented culture” and run “quality management systems”. The term “consumer” began to appear in the U.K. patient satisfaction literature.

While “patient satisfaction” is a term widely used, as a concept it is poorly understood. Fitzpatrick 43 denied the suggestion that patient satisfaction research is part of a wider social movement towards consumerism. It is apparent that clinicians recognized the need to examine service from the patient’s point of view despite the suspicion that the concept of patient satisfaction is essentially threatening to physicians’ status, livelihood and professional standards. One assumption commonly made by health professionals is that surveys will uncover widespread dissatisfaction, whereas in practice the opposite often is true.

3.1 The Purpose of Patient Satisfaction Measurement From 1965 through to the most recent literature, there is general agreement that the purpose of patient satisfaction measurement is to evaluate the health care system and the quality of care it provides from the patient’s perspective.

62 According to Sitzia and Wood 40 the measurement of patient satisfaction fulfils several distinct functions. They are to understand patients’ experiences of health care – measurement of health care services from the patient’s point of view; to promote cooperation with treatment – measurement of the “process of care”; to identify problems in health care – problem areas can be isolated and ideas toward solutions may be generated; and lastly, to evaluate health care – the essence of patient satisfaction research. Jackson et al.44 noted that patient satisfaction measurement is currently used for four related but distinct purposes: to compare different health care programs or systems; to evaluate the quality of care; to identify which aspects of a service need to be changed to improve patient satisfaction; and to assist organizations in identifying consumers likely to disenrol.

3.2 Evaluation of Health Care or Services Provided The process involves defining the objectives of care, monitoring health care inputs, measuring the extent to which the expected outcomes have been achieved and assessing the extent of any unintended or harmful consequences of the intervention. 40 Locker and Dunt 41 emphasized that there should be some external criterion against which ratings should be judged. Therefore, evaluation can be seen either as a technical process, where performance is measured against an agreed set of fixed goals, or as an interactive process where the goals are shifting and defined by the ongoing knowledge, economic and political marketplace.

Among the models of health care evaluation that have been proposed, Coulter 45 suggested that there are at least four aspects of evaluation. They are: evaluation of specific treatment (e.g. drug therapies or surgical procedures), evaluation of patterns of care for particular patient groups (e.g. organization and management for patients with specific condition such as diabetes), evaluation of organizations (e.g. a hospital or a day surgery centre), and evaluation of health systems (e.g. different models of care delivery, such as primary nursing). Cochrane 46 outlined three criteria by which medical therapies should be judged. They are: effectiveness – does the treatment alter or improve the nature of the disease? Efficiency – does the input justify the output? Lastly, equality – is there equal access to the treatment or service by the population served?

63 According to Sitzia and Wood, 40 the Donabedian model was considered to be the most popular model in its time. It uses “structure”, “process” and “outcome” as the three basic approaches to evaluate quality of care. “Structure” generally refers to the organization of the institution delivering care and the conditions under which care is provided. “Process” refers to the professional activities associated with providing care. Lastly, “outcome”, the most important aspect, is not simply a measure of health or well-being, it is a change in a patient’s current and future health status that can be confidently attributed to antecedent care.

There have been further attempts to define outcome of health care. A basic distinction is made between “patient end results” and “process outcomes”, that is, outcomes which change the natural history of the disease, the latter referring to outcomes which occur only when the patient receives medical care. The most popular classification of outcomes was Elinson’s “Five Ds”, (1) death, (2) disease, (3) discomfort, (4) disability and (5) dissatisfaction. These were later further extended to death, disease, physical well-being, psychological well-being, social well-being and quality of life. 47 According to Coulter,45 however, it is impossible in practice to directly attribute the observed outcomes to the process of care, as social, economic and other factors can influence the course of an illness. Also, another problem in measuring outcomes is the definition of objectives. Traditionally outcomes have been defined by professionals and these may differ from the definitions of patients.

3.3 The Concept of Satisfaction Lack of attention to defining the meaning of “patient satisfaction” has been described as the greatest problem in patient satisfaction research. 48 The problem is not restricted to the health field Linder-Pelz 48 noted that the lack of conceptualization of client satisfaction has been reported in public agency programs and indeed in the consumer satisfaction literature as a whole. Ware et al. 49 have been credited for much of the early theoretical work, building the concept of patient satisfaction over a number of years. Ware et al. made the distinction between objective satisfaction reports about providers and care (e.g. waiting times), and satisfaction ratings which attempt to capture a personal evaluation of care which is not possible by observing care directly. They argued that satisfaction ratings should reflect three variables: the personal preferences of the patient, the patient’s expectations and the realities of

64 the care received, and lastly, satisfaction, with the last affected by many different components of that care. In this theory, a satisfaction rating is both a measure of care and a reflection of the respondent.

A number of satisfaction theories were current in the early 1980s, one of the more prominent being that of Linder-Pelz. 48 Linder-Pelz defined patient satisfaction through content analysis of satisfaction studies. Five social-psychological variables were proposed as probable determinants of satisfaction with health care, the first three of which equate directly with Ware’s three determinants. They are: (1) Occurrences – the event which actually takes place, perhaps more importantly the individual’s perception of what occurred. (2) Value – evaluation in terms of good or bad, of an attribute or an aspect of a health care encounter. (3) Expectations – beliefs about the probability of certain attributes being associated with an event or object, and the perceived probable outcome of that association. (4) Interpersonal comparisons – an individual’s rating of the health care encounter by comparing it with all such encounters known to or experienced by the patient. (5) Entitlement – an individual’s belief that he/she has proper, accepted grounds for seeking or claiming a particular outcome. Linder-Pelz’s definition rests on social-psychological theory which expresses satisfaction as an expression of an attitude, an affective response, related to both the belief that the care possesses certain attributes (i.e., components/dimensions) and the patient’s evaluation of those attributes. Thus, patient satisfaction becomes a description of “the individual’s evaluations of distinct dimensions of health care” (p. 580).

A contrary point of view was expressed by Fitzpatrick,43 who argued that even though satisfaction is multi-component, it cannot in fact be viewed as a single concept made up of several determinants. Instead he proposed three independent models of satisfaction, each strongly associated with one determinant. They are:

65 (1) “The need for the familiar”. According to this model, socially created expectations are the primary determinants of the degree of satisfaction. Within this model, expectations and cultural differences directly influence satisfaction. (2) “The goals of help-seeking”. According to this model, the major concern for most patients is not satisfaction but some resolution to their health problem. That, is patients judge a health professional or a treatment simply by whether it helps achieve goals in relation to their health problem. (3) “The importance of emotional needs”. This model emphasizes that most medical problems involve an emotional experience for patients, partly due to the fact that uncertainty and anxiety accompany many problems, but also because many patients feel that they only able to judge health professionals’ competence on non-technical aspects of care. Patients therefore judge satisfaction by observing affective behaviour and communication skills. Fitzpatrick 43 further considered that the term “patient satisfaction” has two distinct interpretations. Firstly, the object of investigation is seen as an attitude or set of attitudes held by the respondent regarding health care. This assumes that people have fairly stable views which can be identified by the researcher. Secondly, an evaluation or set of evaluations is derived from the patient’s value of the medical intervention to his or her specific health problem. The majority of patient satisfaction studies exemplify the latter, and often look only at a single encounter.

In the early 1980s some satisfaction research was carried out according to what was called the “discrepancy model”. Fox and Storms 50 stated that lack of variability in satisfaction responses caused a shift in focus from obtaining stability of results to understanding the conditions under which discrepant findings can be predicted. This implies that the focus has shifted to identify areas of dissatisfaction, as being more valuable than the consistency of satisfaction. Also, Williams 51 added that patient expectations are the key to understanding the reasons for expressed dissatisfaction.

66 3.3.1 Determinants of Satisfaction Expectations . Expectations emerge repeatedly as having a fundamental role in the expression of satisfaction. Stimson and Webb 52 were among the first to suggest that patient satisfaction is related to the perception of the benefits of care and the extent to which these meet patients’ expectations. The importance of expectation is reflected in several definitions of patient satisfaction, and supported by research evidence. Risser 53 , Fitzpatrick 43 and Abramowitz et al. 54 found that not only can patients hold different expectations for different aspects of care, but expectations and satisfaction with specific aspects of care play independent roles in predicting patient satisfaction. As patient satisfaction has been recognized as a component of quality assurance, it is tempting to equate high levels of satisfaction with high levels of quality of care. However, in considering patient satisfaction study results, Locker and Dunt 41 stated that it is necessary that “expressions of satisfaction should always be interpreted in the context of some understanding of the rationale that underlies those expressions rather that being taken at face value” (p. 289). Bond and Thomas 55 found that different levels of satisfaction may indicate different perspectives on ‘certain’ care quality rather than different levels of satisfaction with the same experience. This is the case for physician care. Larsen and Rootman 56 hypothesized (strongly supported by evidence) that the more a doctor’s performance meets patient’s expectations, the more satisfied the patient will be with the doctor’s services. Abramowitz et al. 54 found that the relationship between patient expectations and overall satisfaction is that patients with lower expectations tend to be more satisfied.

However, based on the findings of Sitzia and Wood, 40 there may be some confounding variables that need to be considered. For example, there are existing relationships between level of patient expectations and socioeconomic status on the one hand and associated values and attitudes amongst different patient groups on the other. Researchers including Stimson and Webb 52 have argued that “expectation” in itself is a concept difficult to examine analytically, and as with the concept of “satisfaction”, there have been few attempts to clarify what the term means. The assumption is frequently made that expectations refer to some notion of standards, but few attempts (including one by Fitzpatrick 43) have been made to see whether such attitudes exist as identifiable properties. In the attempt to investigate this issue Stimson and Webb 52 broke down the concept into a simpler form by identifying three categories of expectations.

67 The first is “background” expectations, explicit expectations resulting from accumulated learning about the consultation/treatment process. Although background expectations vary with the illness and particular circumstances, certain patterns of activity or routines are expected, and much criticism centres on behaviour which is at odds with these expectations. The second is “interaction” expectations, which refer to patients’ expectations regarding the exchange which will take place with their doctor, for example the manner and technique of questioning and the level of information released by the doctor. This category is considered the most important of all. The third category, “action” expectations, relate to the action the doctor will take, such as prescribing, referral or advice.

There is evidence that expectations vary according to knowledge and prior experience, and are therefore likely to change with accumulating experience. Bond and Thomas 55 noted that increasing quality of care raises expectations. As a result of increasing expectations, levels of care that were originally considered high may gradually become associated with lower levels of satisfaction. Furthermore, if the models associating satisfaction with the fulfillment of positive expectations are valid, then the high levels of satisfaction that are constantly reported from just about every sphere of health care suggest that the large majority of patients are either very happy with almost everything, or that patients’ expectations are generally low. To further examine the lack of response variability, it is necessary to examine detailed characteristics of patients as well as a number of sociological and psychological issues.

Patient characteristics . It is commonly believed that satisfaction with health care may depend upon variables such as social class, marital status, gender and age. Hall and Dornan,57 in a meta-analysis, concluded that socio-demographic characteristics are at best a minor predictor of satisfaction. Also, Fitzpatrick 43 and Fox and Storms 50 are among the many researchers who have highlighted the lack of consistency of the effects of these variables in satisfaction studies. Perhaps the most consistent determinant characteristic is the patient’s age, with a body of evidence from various countries to suggest that older people tend to be more satisfied with health care than younger people. 58-60 The literature indicates that older respondents expect less information from their doctor and are more satisfied with most aspects of their hospital care.

68 Younger patients are less satisfied with issues surrounding the consultation in the primary care setting, and less likely to comply with prescriptions or medical advice.

Educational attainment . Hall and Dornan 57 reported that educational attainment has been identified as having a significant bearing on satisfaction, the trend being that greater satisfaction is associated with lower levels of education. This United States (U.S.) finding was supported by Anderson and Zimmerman 61 and Schutz et al.; 62 however, there was a lack of supportive evidence from the U.K. It was suggested other factors such as income may be confounding the U.S. evidence.

Socioeconomic factors . The relationship between satisfaction and social class is less consistent, the problem being that socioeconomic variables are often simply not assessed. In 1990, Hall and Dornan 57 revealed that social status had “nearly” significant association with satisfaction. This may be partly explained by evidence from the U.S. suggesting that more affluent patients simply received better treatment from physicians than less privileged patients, even within the same health care facility. Furthermore, U.K. findings suggested that people in higher social classes were better informed.

Gender . Generally it has been found that patient gender does not affect satisfaction;40 however, a few studies have reported that significantly more men than women are satisfied overall with their general practitioner. 63 Also, female in-patients are far more likely to complain of rigid timetables and lack of privacy than men. 64 Furthermore, Hall et al., 65 an American study, reported that in the context of routine medical consultations, lower satisfaction was associated with younger female physicians, and least satisfied were male patients examined by younger female physicians.

Ethnicity . Ethnic origin is perhaps one of the most complex determinant characteristics. Pascoe and Attkisson 66 found evidence that those classified as “whites” on the whole were more satisfied than “non-whites”. In the U.K. much of the work examining ethnicity as a determinant has focused on British Asian patients. Surveys done by Jones et al. in the late 1970s and 1980s, cited by Sitzia and Wood,40 identified several key problems: language

69 difficulties, mainly with general practitioners, hospital staff’s attitudes toward Asian patients, and hospital catering. There is limitation to these findings in that they can only apply to “Asian” groups; other races might have entirely different religious beliefs and cultural values. Nevertheless, different cultural standards and expectations were prominent in the results of these surveys. For example, examination of a woman by a male doctor was a source of distress to some patients. However, a study of ethno-cultural differences in the U.K. general practice context presented a different conclusion. Jain et al. 67 found that the choice of doctor was determined more by the proximity of the patient’s home to the practice premises than by ethnic considerations. There was little evidence that Asian women preferred to be examined by a female doctor.

Psychological issues . Little work has been done to examine possible associations between psychological status in terms of problems such as anxiety and satisfaction. The way in which distress influences responses was examined by Hopton et al. 68 Their survey, using the Nottingham Health Profile, was conducted on 1599 patients and revealed a positive relationship between perceived distress and patient’s age, waiting time, length of consultation, and whether or not psychosocial issues were dealt with in the consultation. Sitzia and Wood 40 argued that it is too simplistic to conclude that a particular dimension of distress influences specific dimensions of satisfaction, and likewise theories that people experiencing psychological distress are more likely to be generally dissatisfied with health care are simplistic.

Psychosocial determinants . Some reports have suggested that various social-psychological artefacts may affect expressions of patient satisfaction. Raphael 69 and Ley 70 found that “social desirability response bias” causes patients to report greater satisfaction than they actually feel because they believe positive comments are more acceptable to survey administrators. Similarly, “ingratiating response bias” occurs when patients use a satisfaction survey to ingratiate themselves with researchers or medical staff, especially if there are any reservations over the anonymity of respondents. Ley 70 also noted that an additional phenomenon influencing responses is simple indifference. Patients may feel that problems will not be remedied and so there would be no point in commenting on them, either because the problem

70 is too trivial or perhaps too large. A number of researchers have suggested that patients may be reluctant to complain for fear of unfavorable treatment in the future. Le Vois 71 suggested that the ingratiating response bias is “self-interest bias”, and proposed that clients in their own self-interest are likely to express satisfaction and in turn continue receiving the service. This theory is supported by both the “economic view”, that individuals seek to maximize their own interest and the “social exchange perspective”, that behaviour is governed by an exchange of activities. Le Vois 71 further suggested that patients who continue in the face of adverse program or personal conditions are most likely to be influenced by this type of bias. Similarly, patients’ evaluations of services may in some cases be influenced by the additional attention implicit in the data collection process and the apparent concern of the research sponsors about patients’ level of satisfaction, and these positive feelings can lead to a positive perception of the service and consequently to positive ratings.

3.4 Components of Satisfaction A factor common to the findings of many patient satisfaction surveys is that few patients express dissatisfaction. 68,54 Whilst such data may please health care managers, lack of response variability is a problem for researchers, who are often forced into comparing positive with less positive responses. This phenomenon may be partly explained by the methodological issue of how questions are asked, whether open-ended questions produce greater criticism than structured questions, and which rating scales best elicit a more critical response. 72-74 One key aspect of response variability is not completely a methodological issue but a conceptual one: the multidimensional nature of satisfaction. 40

Wensing et al. 75 provided evidence that the questioning procedure (method, time and place) and type of scale used affects the degree of dissatisfaction expressed. Greater response variability is found with regard to specific aspects of health care, and there is much evidence to show that patients do in fact distinguish among the dimensions of care when they judge its quality. Furthermore, Williams and Calnan 64 reported a multi-context study of satisfaction, where questions of a detailed and specific nature generated greater levels of dissatisfaction than more general questions. It has become increasingly accepted among researchers that substantial dissatisfaction exists with specific components of care.

71 3.4.1 Classification of Satisfaction Components In 1965 Abdellah and Levine 76 identified the key components of health care as adequacy of the facilities, effectiveness of the organisational structure, professional qualifications, competency of personnel and the effect of care on the consumers. A decade later Risser 51 presented another four components: cost, convenience, the provider’s personal qualities and the nature of the interpersonal relationship, and the provider’s professional competence and the perceived quality of care received. A decade later Ware et al. 49 presented a more definitive taxonomy with eight dimensions: 1. Interpersonal manner – features of the way in which providers interact personally with patients (e.g. respect, concern, friendliness, courtesy). 2. Technical quality of care – competence of providers and adherence to high standards of diagnosis and treatment (e.g. thoroughness, accuracy, unnecessary risks, making mistakes). 3. Accessibility/convenience – factors involved in arranging to receive medical care (e.g. waiting times, ease of reaching provider). 4. Finances – factors involved in paying for medical services. 5. Efficacy/outcomes of care – the results of service provided (e.g. improvements in or maintenance of health). 6. Continuity of care – constancy in provider or location of care. 7. Physical environment – features of setting in which care is delivered (e.g. clarity of signs and directions, orderly facilities and equipment, pleasantness of atmosphere). 8. Availability – presence of medical care resources (e.g. adequate medical facilities and providers). Ware’s classification has been the basis for much of the later work which provided evidence that satisfaction is a multidimensional construct, as suggested by Abramowitz 54 in 1987 and Baker 77 in 1990. However, as many satisfaction studies were conducted in very specific contexts it is understandable that any standard classification never seems entirely appropriate. For example, Rubin 72 listed the important components of patient satisfaction with hospital inpatient care: nursing care, medical care, communication, ward management, ward environment, and discharge procedure. Using a similar format, Abramowitz 54 proposed 10 key areas for hospital care: medical care, housekeeping, nursing care, nurses’ aides, staff

72 explanation of procedures and treatments, noise level, food, cleanliness, portering services, and overall quality.

Researchers have attempted to compare the importance of these components relative to each other. Pascoe and Attkisson 66 assembled six components representing the importance of “service quality” which were ranked by outpatients at a U.S. urban hospital. The most important dimension was found to be the behaviour of doctors and nurses, followed by clinical outcome, the extent to which services provided matched perceived needs, the attitude of auxiliary staff, accessibility of facilities, and finally waiting times. In a U.K. study, Williams and Calnan 64 found the most important components to be firstly professional competence and secondly the nature and quality of the patient/health professional relationship. Calnan 78 argued that all of the above classifications of satisfaction components reveal a principal weakness in that they can be seen as presenting management agendas of health care. These models and the particular instruments used are biased towards issues that concern the providers of health care rather than the users. This opinion was supported by Wensing. 75

Interpersonal Aspects of Care . According to Sitzia and Wood 40 and McIver,42 interpersonal aspects of care have been regarded as the principal component of satisfaction. The two aspects that were regarded as particularly important are communication and empathy. Fitton 79 and Roter 80 proposed that, based on sociological models, the interaction in medical encounters between health professionals and patients exhibits a spectrum of high to low control. Central to these models is the balance of power. Power is primarily related to status and competence. The doctor’s power is carried in a generally higher social status due to more medical knowledge and perceived competence. This balance of power may influence satisfaction.

Successful interactions depend also on the social skills of the participants. Non-verbal communication is often the primary mode of transmitting emotions and attitudes. Body positioning such as location, distance and posture can transmit important perceptions of relative power. For example, leaning slightly forwards, nodding the head and having eye contact make patients see doctors as warmer and more attentive, and these behaviours became associated with higher patient satisfaction.81,82 Reassurance, empathy and familiarity were

73 recognized as important aspects of the doctor–patient relationship, but a direct association with satisfaction is unproved. Other evidence 83 has shown that almost all encounters described by patients as “exceptionally good” focused on aspects of kindness, friendliness and emotional support rather than technical care.

Technical aspects of care . On what grounds does a lay patient assess the technical skill of a health professional, or the quality of technical aspects of care? Fitzpatrick 43 noted that many patients appear to have more confidence in commenting on convenience, cost, and doctors’ and nurses’ personal qualities than in expressing dissatisfaction with medical skill. Hopkins, cited by Sitzia and Wood,40 warned that patients are seduced by the quantity of the technical process, with higher levels of technical intervention associated with greater patient satisfaction. Patients’ views about the technical skill and medical competence of doctors as discussed above are largely determined by their perceptions of quite different qualities of the doctor, such as whether the doctor was friendly and reassuring. However, there is some evidence to suggest that patients do have a reasonable level of technical/medical knowledge about their medical condition. For example, Fitton and Acheson 79 found a positive correlation between doctors’ and patients’ ratings of the seriousness of their medical condition. Stimson and Webb 52 proposed several reasons why the competence gap should not be seen as absolute: • The health professional’s knowledge is never complete. The degree of knowledge about medicine in general or a particular medical problem will vary from practitioner to practitioner. • Physicians can never be certain of the outcomes of their actions, as medicine operates at the level of the probable course of an illness and the probable effect of treatment. • The doctor never has a complete monopoly over relevant medical knowledge. Patients can and many do acquire knowledge from other sources, and some may well have as much knowledge about their condition as a junior or new graduate doctor. • The doctor may not always be in possession of all the information that may be relevant to a particular illness, especially information held by the individual patients. In short, Sitzia and Wood 40 suggested that the main reason why satisfaction studies fail to emphasize the importance of the technical quality of the care delivered is that patients assume a basic level of competence in medical procedures undertaken upon them. As a result,

74 relatively minor considerations, such as the manner of the attending staff and the comfort of the surroundings, assume dominant importance. When the medical procedures or treatments are found to be deficient, and associated with patient complaints (a clear indication of dissatisfaction of the service), such a situation is often handled by different mechanisms in the service provider organisation.

Patient education/Information . The patient’s right to be informed constitutes one of the most important rationales for patient education. This right has been well documented in the policy of “A Patient’s Bill of Rights” (American Hospital Association) and “The Patient’s Charter in the United Kingdom”, cited by Sitzia and Wood. 40 Beyond the patients’ rights, issues of patient education are relevant to legal mandates, particularly regarding “informed consent”. Patient education has further been shown to have cost benefits to society through acquisition of health awareness, consequent reduction in accidents, number and/or length of hospital stays, and more appropriate use of hospital services. Patient education has also been linked with positive clinical outcomes such as improved adherence to a therapeutic regime, reduced anxiety, enhanced ability to cope with symptoms, and enhanced recovery after surgery. Furthermore, patient education and information have been found to improve satisfaction due to the patient’s comprehension and in turn, higher compliance with the doctor’s advice. 83-86

The issue of informed consent for procedures is assuming greater importance globally, partly due to an increase in the complexity of care delivered, as well as the increased likelihood that patients may turn to litigation against medical practitioners following the U.S. example. The satisfaction literature has highlighted the importance of patient information as a component of satisfaction, and that has helped to encourage medical service providers to provide educational materials to patients with all medical conditions.

3.5 The Predictors of Patient Satisfaction Despite the increased focus on satisfaction as an outcome measure and a growing body of research, satisfaction has remained difficult to compartmentalize. While numerous satisfaction surveys have been developed, most with acceptable psychometric properties, the factors individual patients use to deem themselves satisfied remain largely unclear. Consequently,

75 studies measuring predictors of satisfaction have explained only a small portion of the variance of satisfaction, mostly less than 20%. 87 Jones et al.88 commented that despite surveys covering a range of satisfaction variables within and outside the provider’s control, the variance in satisfaction is only minimal, and concluded that other important considerations from the set of unmeasured attributes must provide the bulk of the explanation. Linder-Pelz48 agreed that the low power to explain satisfaction is due to the lack of good models of satisfaction, with most studies relying on post-hoc correlational analysis rather than model- driven research. Even Linder-Pelz’s research into the well accredited socio-psychological determinants hypothesis found that patient expectations, values and perceived occurrences all had independent effects on patient satisfaction, these variables explaining less than 10% of the total variance. Kane et al. 89 proposed two models of patient satisfaction: Model 1: satisfaction = Outcomes + Severity + Demographics + Procedure Model 2: satisfaction = Outcomes(before–after) + Severity(before–after) + Demographics + Procedure The difference between the two models is that the first is based on absolute patient outcomes, while the second is based on incremental improvement in symptoms during the follow-up periods. Although both models had some predictive power, absolute levels of patient health were more predictive than relative changes in functioning aspects. Unfortunately, only 8% of satisfaction was explained by either of these models.

As stated earlier, communication and interaction between physician and patient are some of the aspects that patients judge when rating their satisfaction with care provided. They too have consistently contributed to only a small portion of variance. Social class, gender, race have shown to influence patient satisfaction. Health status and mental state may also be contributing factors. Cleary and McNeil90 and Williams and Calnan 64 all reported that health status appears to play a role, since patients reporting their health to be poor are less satisfied than those who describe themselves to be healthy. Furthermore, other studies such as that of Greenley et al. 91 showed that satisfaction may be influenced by the patient’s mental state, as there are findings suggesting that poor mental state has been associated with lower levels of satisfaction.

76 Unmet patient expectations have consistently affected satisfaction. While most patients have specific expectations for their health care visit, physicians fail to recognize or address those expectations 18% to 42% of the time. Like and Zyzanski 92 reported that unmet expectations account for 19% of the variance in patients’ satisfaction. Jackson et al. 44 confirmed that unmet expectations emerged as the strongest independent correlation with satisfaction, although no specific residual expectation was identified as being more important than another. This finding was consistent with that of Marple et al. 93 Whether unmet expectations are a cause or simply a marker of dissatisfaction is unclear, because the above studies found that an intervention to improve the way physicians addressed patient expectations significantly decreased the number of unmet expectations but did not lead to a significant increase in patient satisfaction.

3.6 When Is the Right Time to Administer a Satisfaction Survey? Jackson et al. 44 highlighted that attention should be paid to the time at which questions about satisfaction are asked. Asking about satisfaction at different times may yield different outcomes and may be measuring different domains. If the desire is to measure satisfaction with specific physician behaviour, then the question may need to be asked immediately after the visit. Satisfaction measured outside the context of an immediate visit may be a proxy for symptoms or functional status improvement rather than a measure of satisfaction. After the patient leaves the office, certainly after 2 weeks, much of the variance in visit-specific satisfaction is directly or indirectly related to improvement in symptoms or functioning rather physician characteristics. While it could be argued that patients are in a better position to determine whether or not they are satisfied at a later time, after they have had the opportunity to decide whether the physician’s advice is “right”, satisfaction at that time is really measuring satisfaction with the patient’s health outcome rather than satisfaction with the individual physician. Very few studies have assessed how well satisfaction correlates with quality of care. This finding is consistent with that of Haas-Wilson, 94 where technical aspects of eye care were objectively rated and compared to the patient’s perception of quality, revealing that patients were poor at assessing technical quality. Jackson et al. 44 suggested two models for patient satisfaction at different times:

77 1. Immediate post-visit satisfaction = Demographics(age) + Patient expectations + Patient functioning + Patient-doctor interaction(receiving an explanation of symptom cause and likely duration). 2. 2-week/3-month satisfaction = Demographics(age) + Patient expectations + Patient functioning + Symptom improvement.

According to these models, the immediate post-visit model explained 26% of the variance in satisfaction, whereas the 2-week and 3-month models explained 38% and 40% respectively. Although this is considerably higher than most studies, it still demonstrates important gaps in our understanding of the factors that impact upon patient satisfaction.

3.7 Summary and the Future of Patient Satisfaction Research Patient satisfaction will continue to be an important outcome measure. The concept of patient satisfaction has been extensively studied since 1966, peaking in 1994, and was thought to correspond to the rise of consumerism in Western medical practice. The literature has highlighted that the concept of patient satisfaction has suffered from a lack of formal attention to its meaning. Perhaps the greatest weakness is that theoretical work has concentrated on the development of models to explain the results of satisfaction studies, rather than questioning the theoretical foundations on which the concepts of “satisfaction” and its “measurement” are based. This may be due to the fact that patient satisfaction is being adopted as an indicator of health care quality by providers under pressure from market competitiveness and forces to improve their performance. Whatever the intentions were, the future of patient satisfaction measurement must include the patients’ views in the audit process.

From this literature review, it is interesting to note that the view among researchers discredits the value of positive results and places more emphasis on the negative results, i.e., what are the “dissatisfactions” that patients are telling us in satisfaction studies? Proponents of the “discrepancy” model argue that satisfaction is entirely relative, defined in large by the perceived discrepancy between a patient’s expectations and actual experience. This model is perhaps particularly attractive to health care systems in which satisfaction responses are prone to a wide range of socio-psychological biases. The literature further suggests that the models

78 require more formal evaluation in the future, but for the present, researchers conducting satisfaction studies should pay greater attention to expressions of dissatisfaction, and the ways of measuring it, rather than seeking to refine instruments which have repeatedly reported high levels of satisfaction with the services.

Many models of patient satisfaction suggest that satisfaction is to some extent determined by certain subject characteristics. Expectations appear to be the most important, though the demographic variables of age, educational attainment, gender and ethnicity have all been shown to influence the ratings of satisfaction. However, a degree of caution is warranted, in that we must be aware that most of these variables are rarely assessed in satisfaction studies, much less considered in the analysis of responses. Therefore, further doubt may be cast on the validity of the findings. The literature has also indicated that there is general acceptance of the notion that various aspects of care, independent of each other, have to some extent a bearing on over-all satisfaction. Ware et al. 49 identified eight categories as the “components” of satisfaction. A major weakness of these categories is that they are based upon criteria set by management and professionals rather than emphasizing lay patient perceptions of care. This has given rise to the movement towards using satisfaction as an audit tool, in which large-scale surveys appear as the effective approach to evaluate patient satisfaction.

Researchers have highlighted the need to continue the emphasis on a patient-centred approach rather than on criteria set by the provider or management of the health care organization. Qualitative approaches to assessing interpersonal aspects of the patient-doctor relationship, such as audiotape or videotape coding of actual encounters, or perhaps an interview or oral narrative approach as a means of patients describing their experiences, may be necessary to tease out provider communication skills, affective aspects of the interaction, nonverbal behaviours, or other components which cannot be captured by surveys. While satisfaction studies have a role to play to assess quality of health care delivery, they must be part of a wider range of review of service quality.

79 3.8 Principles and Concepts of Patient Dissatisfaction To date, relatively few studies have focused specifically on dissatisfaction. Dissatisfaction has received little attention since it has been assumed to be the opposite of satisfaction and thus already defined. A series of assumptions have also been made about dissatisfaction, which may or may not compromise the validity or usefulness of findings. Coyle and Williams 95 argued that there is a need to clarify the concept of dissatisfaction, to clarify what the studies of patient satisfaction can and cannot tell us about dissatisfaction, and to address the complexity of patient experiences from which researchers can best capture and learn. Since the aim of patient satisfaction studies is to be responsive to the needs and wishes of patients, it would seem appropriate that reporting patient dissatisfaction should assume centre stage. A key problem with patient satisfaction research is that it highlights little about dissatisfaction, and it is often characterized by an extremely high level of overall satisfaction. 41,50

3.8.1 Satisfaction/Dissatisfaction As a Continuum Coyle and Williams 95 suggested that researchers should be cautious about exactly what they can infer about dissatisfaction from studies of satisfaction on the assumption that the satisfaction scale is a continuum and that satisfaction and dissatisfaction are the opposite ends of the same construct. Indeed, Avis et al., 96 Fitzpatrick & Hopkins, 97 and Williams 51 reported that qualitative studies have found little evidence that patients think and evaluate satisfaction in terms of a continuum. Furthermore, many satisfaction studies have attempted to measure a concept of satisfaction which has been inadequately theorized. In particular, they have drawn on an expectations model which has little empirical support. 48,51 Thus, the concept that dissatisfaction represents the opposite of satisfaction may be unfounded.

3.8.2 Dissatisfaction As an Expectation/Unfulfilment Model Many patient satisfaction studies, such as those of Babiker and Thorne, 98 Dunn et al., 99 Larsen and Rootman 54 and Williams and Wilkingson 100 have drawn on a model which assumes that satisfaction results from the fulfilment of patient expectations. The model logically assumes that dissatisfaction will result from the failure to meet patient expectations. Yet studies have found inconsistency or no relationship between expectations and satisfaction. Coyle and Williams 95 considered that the contradictory nature of findings reflects the lack of consistency

80 in conceptualizing “expectations”. What was illustrated was that expectations can vary across studies. The different ways of conceptualizing expectations can influence how researchers interpret their findings. For example, in Fitzpatrick and Hopkins’ study, 97 the “goals” people had in seeking treatment were to address their concern and seek reassurance, to alleviate symptoms and to seek prevention. They were not regarded as expectations. However, in study of Avis et al., 96 similar types of goals were conceptualized as expectations. Other authors have conceptualized the vague hopes of cardiology and respiratory patients for reassurance as expectations. Fitzpatrick and Hopkins 97 found that patients’ goals in seeking care were related to satisfaction, but they were not regarded as expectations. They reported finding no relationship between expectations and satisfaction. To these authors, no relationship existed because their patients had not expressed any firm expectations other than vague goals. Had the “goals” had been conceptualized as “expectations” as they were by Avis et al., 96 a positive relationship would have been reported. Thus, the empirical evidence as to the relationship between expectations and satisfaction does not demonstrate any clear consistent positive association, and so it cannot be assumed that dissatisfaction will result from failure to meet expectations. The concept of expectations requires further theorization and clarification to enable researchers to compare findings across studies and in different health-care settings.

It has been suggested that expressions of satisfaction and dissatisfaction cannot be seen as opposite but as two sides of the same coin. This opinion was supported by Mulcahy and Tritter, and Pope cited by Coyle & Williams. 95 They observed satisfaction and dissatisfaction to co-exist side by side. An individual could be satisfied with an aspect or attribute of care, but still have a number of dissatisfactions or reservations about it.

3.8.3 Towards a Definition of Dissatisfaction Some attempts have been made to define dissatisfaction based on the earlier work in sociology, examining the emergence and transformation of disputes. Felstiner et al. 101 developed a model called “naming, blaming and claiming”, where the encounter experiences became grievances, and grievances became disputes. In such a process, an unperceived injury became perceived (naming), which transformed it into a grievance, and the injured person could then attribute blame or responsibility to another individual or social entity (blaming).

81 Finally, it transformed into a claim, when the person voiced grievance to the person or entity believed responsible in order to achieve some remedy (claiming). These transformations were regarded as subjective, unstable, reactive, complicated and incomplete. The feelings of injured people will change over time, as they define and redefine their perceptions of their experience in response to the advice, behaviour and expectations of others, including intimates, authority figures, agents and opponents.

Recent definitions of dissatisfaction tend to focus on an event or incident as expressed at a specific point in time. According to Coyle and Williams, 95 Verkuisen, Mulcahy and Tritter defined dissatisfaction by distinguishing between the negative emotions felt immediately after an experience. They found that while satisfaction was expressed in vague general terms, respondents were far more specific about the sources of their dissatisfaction.

3.8.4 Dissatisfaction As an Artefact of Method Expressions of dissatisfaction may prove to be an artefact of the methodology. As cited by Coyle and Williams, 95 the data in Mulcahy and Tritter’s study were collected by interviewers who ticked boxes and/or recorded the words of the respondents in longhand. It is likely that in such situations interviewers are more likely to record examples where interviewees are definite about their grievances. Any complexity, ambiguity, uncertainty and subtlety will be difficult to capture in a study that depends on interviewers recording in longhand the interviewees’ feelings and experiences. In contrast, the method used by Bramadat and Driedger was audio-recording a woman’s talk, which may have allowed the woman to talk more freely about the negative feelings which were still crystallizing, and also resulted in the researchers recording more vague feelings and perceptions.

To explore the more ambiguous, subtle and complex feelings of people towards their experiences of health care, researchers need to use methods which allow people space to tell their stories as fully as possible. Studies 96,102,103 using qualitative methods have found that patients experience some difficulty in verbalizing what they mean by satisfaction and dissatisfaction. Patients are reluctant to talk in terms of dissatisfaction or to describe themselves as dissatisfied. Rather they comment on things that “are bothering them”, feel that

82 they were “being kept in the dark”, they “were given incomplete information”, and they “were not involved in the clinical decision making”.

3.8.5 Dissatisfaction As a Rejection of Passivity As reported by Coyle and Williams, 95 studies have found that many people who experienced problems did not complain due to the perceptions of powerlessness, fear of retribution, and fear of being labelled as a nuisance or unpopular. Other studies have also found that patients were grateful for the care given by nurses, and tended to make allowances for shortcomings by attributing responsibility to the lack of resources or to the system in general. The authors also found personal identity threat is a key concept delineating the grounds for patients’ dissatisfaction, and is better able to capture the complexity of patients’ experiences, feelings and values than the less theorized concept of satisfaction. The authors believed this would be a useful starting point for developing a framework to understand more fully and categorize the contradictory attitudes, feelings and beliefs that patients express about their health care encounter. Since there is evidence to suggest that satisfaction can mean different things to patients in different health care contexts, the same may be true for dissatisfaction. Therefore, more qualitative work is needed to tease out the subtle differences in meanings. Comparing meanings across different settings will enable researchers to develop a framework for assessing patients’ views which is conceptually sound, and from which robust research tools and measures can be designed.

3.9 Summary To date, lack of conceptual clarity and inadequate theorization are the main problems facing patient satisfaction research. This has led to a number of unwarranted assumptions being made about the concept of satisfaction and to the neglect of dissatisfaction. The thinking on the nature of attitudes such as satisfaction and dissatisfaction has been primitive. So far, there has been a tendency to conceiving them as running in straight lines from positive to neutral to negative feelings about an aspect or issue in question. However, there is no proof that the model of a linear continuum is correct, though it does make things easier for measurement purposes. For all we know, it may be in any shape or form. It is likely that changes to services will stem more from the limited number of studies of complaints than from the large number

83 of satisfaction surveys being carried out. On the other hand, complaint studies can not be relied on alone since many people may willingly express dissatisfaction and yet not make any form of complaint. If this “silent” group of patients is to be heard and services changed, a re- examination and reconceptualisation of dissatisfaction is required. Future research should consider dissatisfaction as having the following characteristics: • It is a subjective transformation which involves the crystallization of a strong, negative emotion experienced into a more stable negative interpretation of the encounter. • Categories such as power, attributions, and personal values are variables which intervene between the experience and the expression of dissatisfaction. • Expression of dissatisfaction involves elaborate justification which includes assessments of culpability, responsibility and blame. • Issues related to self-concept and personal identity are deeply implicated and need to be responded to in accounts of dissatisfaction.

3.10 Measuring Issues in Patient Satisfaction Studies The literature clearly indicates the importance of patient perception and the desirability of maximizing patient participation in and satisfaction with medical care. Because this concept is so much a part of current rhetoric in health care, there is a trend to include patient satisfaction as part of the evaluation of health care quality. Despite the large number of studies of patient satisfaction, so far there are no clear findings but various theoretical bases have been generated. It has been difficult, even impossible, for investigators to use theories and scales developed by other researchers, which hampers comparison among studies in different settings. Also, not only has the literature shown that there is a major lack of understanding in defining the concept of satisfaction, but also there is major gap in the study of patient satisfaction with medical outcomes, even though it has been defined as the most important aspect in evaluation of health care and services provided. 40 Furthermore, there has been little clarification of what the term means either to researchers who employ it or respondents who report it. Another issue is the process by means of which respondents decide whether they are satisfied or dissatisfied. What are expressions of satisfaction and dissatisfaction based on? Measurement issues in patient satisfaction studies have suffered, and given the preoccupation of most researchers with the identification of socio-demographic variables associated with

84 satisfaction, little attention has been directed towards developing a well-defined sociopsychological theory of satisfaction. 40

Many clinicians appear skeptical of the usefulness of satisfaction measures. This perhaps reflects a belief that patient satisfaction is an administrative issue and is an indicator of health care quality matters such as the cost and accessibility of services, but is not concerned with the effectiveness of the treatment or interventions patients have had. There is also a belief that in some cases, clinicians have no control over patients’ health care experiences. There is a need for clarity about how satisfaction measure differ, because conclusions about satisfaction vary depending on the characteristics of the measure used. 40,51,104,105

3.10.1 Characteristics of Satisfaction Measures According to Hudak et al., 115 the characteristics of satisfaction measures fall into two major categories: content and method.

Fig. 3-1. Characteristics of patient satisfaction measures (Hudak et al.). 106

In the Figure 3-1 “Content” refers to the focus or substance of the measure, which has four axes representing the fundamental ways that any satisfaction measure can be classified and identified. These are: 1. Global or Multidimensional Measures may be global, with one to two questions about overall or general satisfaction. As this is a single dimension, it is not known what patients are thinking about in rating satisfaction, what aspect(s) of health care they are

85 including or excluding in making decisions about satisfaction, why the question received high or low ratings, whether it would be rated the same by different patients in a reproducible manner. Such measures tend to produce high levels of satisfaction, which can mask specific dissatisfactions and fail to provide detailed information indicating where changes or improvement are needed. Alternatively, the focus can be multidimensional, with multiple items probing satisfaction with different aspects. All patients are explicitly thinking about and rating the same aspects of care. The most common dimensions which represent the major characteristics of providers, health, and medical care services are interpersonal care, technical quality, accessibility and convenience, financial aspects, efficacy and outcomes, continuity, physical environment, and availability. 107 However, recent work indicates that what patients consider important are amenities (food, parking, cleanliness), being treated with respect, being involved in treatment decisions, having someone show interest and concern and taking the time to listen and explain. 106 Failure to communicate information about the condition and treatment options is the most frequent source of patient dissatisfaction. 43,106 Research has suggested that patients recognize distinct dimensions of care when forming an opinion about its quality. 40 For this reason, multidimensional measures produce greater score variability and have higher reliability and validity. 2. Care or outcome The focus of the measure may be satisfaction with either care or treatment outcome. The association between these concepts is complex and not well understood. There is evidence to indicate that many patients evaluate care and outcome separately. 106 To many patients, who also agree with clinicians, treatment outcome is the most fundamental important. The measure of care is patients’ rating of the quality of the medical care process they received. The measure of treatment outcome is patients’ rating of particular treatment interventions they received. Most published studies have emphasized satisfaction with care, only 4% emphazing satisfaction with treatment outcome. 106 Cleary & McNeil, 90 Hall and Dornan 108 and Carr-Hill 109 supported

86 the view that the perceived improvement in health is a predictor of patient satisfaction, but this issue has not been examined extensively. Since the end result of medical care is perhaps the ultimate criterion for quality of care, it is surprising that there have not been more studies of this type. Although satisfaction with the treatment outcome may contribute to satisfaction with care and vice versa, these concepts should be assessed separately, because they represent distinct phenomena that are more validly conceptualized from different perspectives. Therefore, when measuring satisfaction with treatment outcome, it is a challenge to ensure that questions are constructed in a way which requires patients to separate the unique relationship between their bodies and particular treatment interventions from questions about the experiential, emotional and social aspect of the treatment outcome. There are many standardized multidimensional measures of satisfaction with care and healthcare plans to choose from, such as The Health Plan Employer Data and Information Set (HEDIS) 106 and The Consumer Assessment of Health Plan (CAHPS), 105 but when it comes to satisfaction with treatment outcome, standardized multidimensional measures have yet to be developed for many clinical conditions and in most cases satisfaction has been assessed using global measure such as those found in the spine literature106 and cataract literature. 110- 113

3. Generic or disease-specific Measures may be generic, intended to be used in any patient population where patient satisfaction information is collected. Such measures allow comparisons across conditions and settings. They cannot, however, reflect sources of satisfaction or dissatisfaction that are unique to a particular disease or health care setting. Disease-specific scales are designed to be used in particular patient populations, and are sensitive to differences in satisfaction associated with a particular context or condition. Satisfaction with treatment outcome is likely to be captured more precisely by a disease-specific measure. This measure covers three dimensions: information received from the provider, caring, and effectiveness of treatment.

87 4. Direct or indirect Direct (also known as specific or micro) measures ask about specific providers or services, or specific events or episodes the patient experienced with health care and the health care system in general. Because of the specificity, direct measures are considered by clinicians to be more appropriate and informative for probing satisfaction with specific medical encounters, specific settings or particular treatment interventions. They can also provide useful information for continual quality-improvement programs or program evaluation. Indirect (also known as general or macro) measures ask about doctors or health care in general or about patients’ general experience over a given time frame.

Again with reference to Figure 3-1, “Method” refers to how the measure is administered and presented. Methods can be: 1. Factual or affective Measures may focus on factual aspects of care, the facts of what actually occurred. According to Ware et al., 47 the ratings are subjective and presumed to “capture a personal evaluation of care that can not be shown by observing care directly” (p. 247). An example question is, “How long did you spend with your physician today?” If the information is used as part of a quality assurance program, factual information can be readily interpreted and better reflect the quality of care than ratings of satisfaction. Affective measures emphasize patients’ perception of what occurred. An example question is, “Did your physician spend enough time with you today?” – an affective question emphasizing not the absolute period of time spent with the physician, but rather the patient’s perception of the adequacy of that time. If the goal is to understand how patients perceive the care they receive, subjective perceptions or ratings are appropriate. These types of ratings are considered both a measure of care and a reflection of the respondent, because they are influenced not only by the care received, but also by patients’ preferences and expectations.

88 2. Open- or closed-ended questions The questions may be open-ended or unstructured questions that ask the patient to comment in writing on the services received. Closed-ended questions force patients to select a response among a limited number of possible responses generated by the questionnaire developer. Hudak et al. 106 suggested the use of both closed- and open-ended questions, as they would provide a more complete understanding of satisfaction. A perfect example is provided by Nork et al., 114 who combined the closed-ended question, “How satisfied are you with the overall results of your back surgery?” (With possible responses: very satisfied, fairy satisfied, not too satisfied, not at all satisfied) with the open-ended question “If not too satisfied or not at all satisfied, what are the reasons for your dissatisfaction?” 3. Self- or interviewer-administered Most satisfaction surveys are written and mailed out to patients for self-report format. Alternatively, the survey can be done by interviewer. Research has shown that the latter format may yield higher satisfaction scores but has potential bias due to the probing by the interviewer. Also, the additional cost and time required must be considered. However, in some cases an interviewer- administered method is preferable, because little is known about how patients evaluate satisfaction, especially about non-respondents who potentially have much to teach us about context-specific sources of dissatisfaction. Actively seeking and focusing on reasons for dissatisfaction may be most effectively accomplished in an interview, rather than by self-report questionnaire, because a well-trained interviewer can effectively probe for sources of dissatisfaction not easily elicited using a standardized measure. 4. Response formats The response formats for closed-ended questions vary. Although studies comparing different response formats have been reported, it remains unclear which format(s) are superior. Ware and Hays 105 demonstrated that a 5-point evaluation rating scale yields lower mean scores, greater response variability, and higher correlations with measures of behavioural intention than a 6-point

89 satisfaction scale. Ross et al. 115 recommended the use of the evaluation rating scale to deal with the acquiescence problem in satisfaction measurement. Part of the issue is related to the framing of the questions themselves. For example, compare “How would you rate the technical quality of this visit?” to “How satisfied are you with the technical quality of this visit?” The first question asks for an evaluation of technical quality, whereas the second asks about satisfaction with the technical quality. The literature has highlighted the need to clearly distinguish between an evaluation of care received and satisfaction with that care. 40,105-107 Two recent qualitative studies 115,116 have highlighted the complexity of patient satisfaction and the concern in evaluations of care and satisfaction with care. They show incongruity between what patients actually expressed in interviews about their health care experiences and their reports of satisfaction when standardized satisfaction measures were used. Dougall et al. 116 found that although patients verbally and on standardized patient satisfaction measures expressed high levels of satisfaction, in-depth interviews showed many negative perceptions and experiences. They therefore concluded that standardized patient satisfaction measures alone are inadequate indicators of patients’ experiences in health care delivery. These findings again reflect a certain amount of ambiguity about the concept of satisfaction itself and emphasize the need for clarification regarding the association between perceptions, experiences and expressions of satisfaction.

3.10.2 Bias Issues According to Hudak et al., 106 measurement of patient satisfaction suffers from number specific methodological problems: selection bias, high undifferentiated levels of satisfaction, and acquiescence bias.

Selection bias . Satisfaction is usually measured at the end of a treatment. Unfortunately, dissatisfied patients are more likely to withdraw from treatment before completion, particularly when care extends over a period of time, and they are therefore underrepresented in samples of respondents. This systematic bias toward representation of individuals who have

90 completed treatment in studies of patient satisfaction may yield high satisfaction scores, but these scores can be misleading and show little about where improvements in care are needed or when less than desirable treatment outcomes are obtained, and the roots of dissatisfaction will not be discovered. Ferris et al. 117 have suggested that to minimize this bias in continuous care settings, a cross-section of patients should be sampled to obtain information from patients who have varying levels of exposure to the physician or treatment. In episodic care settings, patients should be sampled when care is completed. Patients tend to describe their experiences in terms of episodes of care rather than single visits, particularly when seeking care for a complicated condition. 118 When possible, satisfaction questionnaires should be given (rather than mailed) to patients known to be leaving the program or treatment or practice. Blais 119 reported that although patients who discontinue treatment reported lower satisfaction with some dimensions of a program or care, there were no significant differences in other dimensions between those who withdrew and those who completed treatment. For this reason, Blais suggested that rather than asking only about satisfaction, it is important to explore patients’ actual reasons for leaving the program or treatment or practice. This information may provide insight into those dimensions of care that have been influential in the decision to leave, and should be considered in efforts to reduce the withdrawal rate and to highlight any external factors unrelated to satisfaction that contribute to attrition.

3.10.3 High Undifferentiated Levels of Satisfaction According to Hudak et al., 106 from a measurement perspective, high undifferentiated levels of satisfaction are a constant problem irrespective of the population studied, the method used, or the target of the ratings. When the distribution of satisfaction scores is highly skewed or clustered in only a few response options at the top of the possible range, it is almost impossible for the measure to detect any improvement or distinguish different levels of satisfaction. Although high levels of satisfaction may look good, these results are of little use when they cannot detect any differences in satisfaction, especially related to the outcomes of different treatment interventions. This is possibly due to overrepresentation of patients who have completed a treatment or program (e.g. selection bias), the use of global measures, or it is also possible that it is an accurate reflection of patients’ satisfaction with a particular health care service or treatment outcome. To minimize this effect, multi-item measures not only yield

91 greater score variability, higher reliability and validity, but should also help to clarify whether the right questions have been asked or whether the patients are truly satisfied. Other approaches would be to force respondents to rank the different aspects of care, and increase to the number of points at the positive end of the satisfaction scale. 106

3.10.4 Acquiescence Bias Sometimes respondents in patient satisfaction research have a tendency to agree with statements of opinion regardless of content. Agreement with favorably worded items results in higher levels of satisfaction, whereas agreement with negatively worded items results in lower levels of satisfaction. Single-item measures containing all favorably or all unfavorably worded items are prone to this bias. Ross et al. 115 suggested the use of neutrally worded items and response formats, or rating scales such as poor, fair, good, very good, excellent as a way to deal with the problem. However, carefully framed questions are also important, as mentioned earlier. There is no specific measure for estimating the extent to which acquiescence bias is operating in a given situation. It is reasonable to assume that acquiescence bias is likely to influence satisfaction results to some extent. Researchers should consider this bias as one possible explanation for high levels of satisfaction. However, group differences in satisfaction scores of one standard deviation or more are unlikely to be due to acquiescence bias and probably reflect true group differences in satisfaction.

3.11 Summary The literature has shown that although the study of patient satisfaction has a long history, it is still a relatively new field. Despite a surge in the popularity of using patient satisfaction measures over the past three decades as a way of including patients’ perspectives in the planning and assessment of services, different issues remain to be explored. It is not possible to recommend any particular measure, because no single measure alone is ideal. The literature has highlighted the need for caution and recognition of measurement issues and the potential reasons for variation in results when satisfaction measures perform differently. This understanding will be of value if it increases the specificity with which clinicians select measures to achieve their purposes.

92 3.12 Psychometric Measurement in Quality of Life/Patient Satisfaction The goal of medical care for most patients today is to obtain a more effective life and to preserve functioning and well-being. It is agreed that the patient is usually the best judge of whether these goals have been achieved. 110-113 It is no surprise that measurement of patient satisfaction stems from the measurement of quality of life. Data concerning patients’ experiences and treatment are not routinely collected. According to Ware et al., 120 one reason for the lack of information is the lack of valid methods of data collection that are easy to use. Over the past 10 years there have been attempts to construct validated standardized questionnaires to assess quality of life. As result, an abundance of psychometrically validated instruments or questionnaires have been developed. Initially they were generic, some were useful with diverse groups and treatments, and some addressed general health, not specific to any age, disease, or treatment groups. Like anything that is developmental, these instruments evolved and have been continuously replaced by better ones, or more streamlined to include both breadth and depth of measurement, or modified to make them more suited to a specific population being investigated. A number of examples of these modifications are worthy of mention. Ware et al. 121 modified the Medical Outcome survey (MOS) 20-items Short-Form General Health Survey, SF-20, in order to reduce respondent burden while achieving the minimum standards of precision for the purpose of group comparisons involving multiple health dimensions. Ware et al. 120 also modified the Medical Outcome Survey (MOS) 36-item Short-Form General Health Survey, SF-36, in order to standardize a health status survey, enhance content validity and provide scales that are more likely to detect medical and social differences in health status and changes in health over time in research, health policy evaluation, and general population surveys. Brazier et al. 122 and McHorney et al. 123 validated the SF-36, both agreeing that while the SF-36 is comprehensive, brief and easy to use, it may not be adequate for evaluating elderly patients, those poorly educated and in poverty, and patients with both medical and psychiatric co-morbidity. A supplemental battery of items for these groups is recommended. The evaluation highlighted that, “selecting measures of health status for specific applications involves choosing the right horse for the right course” 123 (p. 60). The literature review shows that these surveys are insufficient to address important issues confronting individuals with ocular conditions such as cataract and refractive error.

93 3.12.1 Evaluation of Patient Functional Impairment Caused by Cataract Assessment of patient functional impairment related to vision is critical, not only to demonstrate the effect on quality of life, but also to evaluate indications for intervention and to be able to measure the benefit of the interventions such as cataract surgery. Despite its importance, relatively little work has been devoted to developing instruments that measure functional impairment caused by cataract. According to Steinberg et al., 110 “Bernth-Petersen developed such instrument more than two decades ago, little research has been published nor has been employed by ophthalmologists in United States. Three other instruments which measure vision-related functional impairment were published in 1992, but thus far none has been incorporated into routine clinical practice” (p. 630-632).

As part of an American federally funded effort to clarify the relative merits of alternative clinical practices, including their impact on the functional status of patients, a number of instruments/surveys were developed relating to the management of cataract and assessment of the outcomes of cataract surgery. Among them was the VF-14, a 14-item visual functioning index developed by Steinberg et al. 110 A questionnaire provides information not conveyed by visual acuity or a general measure of health status. One interesting finding from use of this instrument is that the correlation between visual acuity and patients’ satisfaction with their vision was zero. In other words, some patients with a particular visual acuity are satisfied with their vision, while other patients with the same visual acuity are dissatisfied with their vision, regardless of whether the visual acuity is low or high. Nevertheless, the authors felt that VF-14 score and visual acuity were complementary, with each providing information likely to be of value in assessing the visual and functional status of cataract patients. Five years later the VF- 14 was criticized as impractical. Uusitalo et al., 112 authors of VF-7 (a 7-item visual functioning index), stated that the VF-14 was too time-consuming compared to measures of visual acuity, and showed with Spearman rank correlations that seven of the 14-items/questions were sufficient to describe functional impairment that can be affected by cataract. Furthermore, the VF-7 only took half the time needed for measurement, and thus was more practical to use in clinical practice.

94 3.12.2 Evaluation of Patient Satisfaction Following Cataract Studies evaluating outcomes of cataract surgery have used a combined approach of studying the change in subjective visual function, the change in visual acuity, and refractive error, as well as the augmented subjective visual function as measured by validated survey instruments. 110-112 Among these studies is that of Monestam et al., 113 who hypothesized that there was a discrepancy between the number of patients with a successful operation using visual acuity as a criterion and the number of patients who say they are satisfied with the surgery. Also, there was a discrepancy between poor visual acuity results and the fulfilment of patient expectation of the surgery. They found that only 8% of patients were dissatisfied, and most of those had concurrent age-related maculopathy, diabetes, or glaucoma. The authors emphasized that the dissatisfaction group was too small to have any meaningful statistical comparison or to be statistically analyzed separately. Patients with poor visual acuity after surgery did not report worse visual ability or greater dissatisfaction. This confirms the complex relationships between patients’ subjective visual ability, surgical outcome, and patient satisfaction. The authors concluded that satisfaction is not unidimensional and is not solely related to visual ability or visual acuity, and advised closer examination of the symptoms which cause visual impairment in cataract patients.

It is generally agreed that refractive error is not a pathological condition, whereas cataract is, but both conditions cause a definite degree of visual impairment qualitatively as well as quantitatively. The literature has shown there is increasing interest in outcomes studies, focusing on the patient’s perspective of perceived visual disability caused by cataract rather than the traditional Snellen visual acuity. The U.S. federal panel in charge of the development of practice guidelines for cataract management concluded that “instead of the-risk-to benefit ratio, cataract surgery is indicated when a cataract causes functional disability considered by the patient as sufficient to warrant undertaking the risks of cataract surgery, regardless of the level of visual acuity” 110 (p. 636). In view of this and the literature on visual impairment caused by cataract, there is more reason to understand patients who have visual/functional impairment caused by refractive error and their satisfaction with treatment outcomes.

95 3.12.3 Evaluation of Patient Functional Impairment Caused by Refractive Error Traditionally, clinical measures of refractive status such as refraction, uncorrected and best- corrected visual acuity have been the primary considerations used in evaluations and comparisons. However, research into patient functional impairment caused by cataract has shown that patient-reported visual ability, satisfaction, and symptoms are aspects not detected by traditional clinical measures. Therefore, there is a need for measuring subjective outcomes. Although there are validated generic as well disease-specific outcome questionnaires 110-112,120 , these instruments are insufficient to assess patients with refractive error, especially those undergoing refractive surgery. According to Vitale et al., 124 the National Eye Institute has recognized the need to study quality of life and functional status as perceived by the patient with refractive error in order to assess the full impact of treatment option or the disease process. Vitale et al. 124 developed the Refractive Status and Vision Profile (RSVP), which measures self-reported functioning, symptoms, health perceptions, and expectations in individuals with refractive error. They found that the responses from patients who were considering refractive surgery were somewhat different between the first and second administrations of the RSVP. The authors believed that this finding was due to the patients’ reactions to information they received during their consultation, which changed their knowledge and expectations. The authors concluded that the RSVP is a useful tool to measure a range of visual, functional, and psychological impacts of refractive error that are likely to be important to patients. The future analysis of the pre- and post-operative data should prove useful in identifying patients who experience a change in health-related quality of life after surgery, and whether the items are predictive of actual post-operative status.

3.12.4 Evaluation of Patient Functional Ability and Satisfaction Post-Refractive Surgery Patient functional ability and satisfaction post RK. In the early 1980s RK was in high demand by myopic individuals. Amazed at this phenomenon, ophthalmologists and laymen alike have postulated that these people elect the surgery for occupational or cosmetic reasons, or for reasons of psychological imbalance. 125 To investigate this phenomenon, the National Eye Institute initiated the Prospective Evaluation of Radial Keratotomy (PERK) study to identify the demographic, motivational and psychological characteristics, the safety and efficacy of

96 RK, and patient satisfaction with the procedure. The investigation produced a number of studies.

Bourque et al. 125 found that the PERK subjects were highly educated and had high annual incomes. They thought they were more visually disabled than the myopes in the general population and their primary motivation for surgery was to be free from corrective lenses. They were not psychologically abnormal or high risk takers, contrary to ophthalmologists’ initial speculations. The PERK subjects exhibited two interrelated dimensions: (1) a true fear of being unable to see, fear of losing the natural vision, and fear of losing corrective lenses, and (2) dislike of glasses or contact lenses for reasons of inconvenience, discomfort, and interference with participation in sports.

Bourque et al. 126 found that three major factors influencing patient satisfaction were uncorrected visual acuity, residual refractive error, and fluctuation in vision. A multiple regression equation incorporating these three variables, glare and patient sex was able to predict 46% of the variance in patient satisfaction, UCVA and refractive error being the strongest predictors, and they were highly correlated, their combined effect on patient satisfaction being 34%, only 2% more than that of visual acuity alone. It was concluded that traditional measures of visual acuity and refraction inadequately describe the visual experience, and that contrast sensitivity and night vision may account for some of the variation in satisfaction. It was also found there were differences between male and female satisfaction. The authors felt that past visual history, motivation for seeking surgery, and the extent to which expectations were realized may help to explain both the differences between males and females and some of the unexplained variance in post-operative satisfaction.

Bourque et al. 127 found that after four years, 64% were lens-free for both distance and near vision. By six years, 52% were lens-free, the decline being due to the onset of presbyopia, increased for near vision from 18% to 25% and decreased for distance vision from 41% to 27% of the time. The patients’ concern about their eyes declined from 47% to 9% after RK, suggesting that RK increased patients’ visual quality of life. The study found that three factors explained 47% of the variance in satisfaction: (1) reporting no worry, pain, or restriction in

97 activities due to the eyes; (2) not having to wear lenses for distance or both distance and near vision; and (3) having a visual acuity of 20/20 or better in both eyes. They concluded that, “after six years, most patients in the PERK study could see at distance without lenses even if they were not completely lens-free. Increased need for lenses for near vision with age does not offset this improvement. After all, improved distance vision was the patients’ aim” (p. 431).

Patient functional ability and satisfaction post-PRK . In the early 1990s photorefractive keratectomy emerged. Clinically, PRK went through an intense evaluation to assess the procedure’s safety and efficacy, but subjectively it did not undergo the same vigorous investigation. More specifically, questionnaires were constructed to assess only overall patient satisfaction with the procedure. 21,128-136 Waring 137 commented, “Over 90% of patients who have corneal refractive surgery would elect to have it again, would recommend it to a friend, and express ‘overall satisfaction’. But such positive conclusions are often punctuated by patients adding, ‘But, I wish I saw as sharply as I did with my glasses… I wish I did not see halos and ghosting images at night.’” (p. 214). Unfortunately, only a few studies have dealt with subjective issues, and little correlation has been presented between clinical and subjective evaluation. For instance, it has been well documented in literature 11-13,29,130,132,136 that approximately 80% to 90% of patients achieve an uncorrected acuity of 20/40 or better, and this level of acuity is often used as a bench-mark of surgical success, but does it equate to, or have any correlation with the patient’s own satisfaction level? Waring 137 reported, “Well over 90% of patients could see 20/20 or better best-corrected before surgery, postoperatively over 90% of the operated eyes achieve 20/40, commonly referred to as driver’s license vision – at this level the surgeons said we are doing much better” (p. 213). Werblin 138 also commented, “In my experience patients who use these devices are highly critical of any visual outcome less than perfect, and even the difference between 20/20 and 20/15 can be a major issue. Why is it that refractive surgeons must use this new concept of ‘acceptable vision’ to explain their imperfect art? This is not just a semantics issue, but creates very fundamental problems for both patients and surgeons” (p. 300). Waring 139 again stated, “If 10% of patients express dissatisfaction or have difficulty with halos or night driving, a few million patients received excimer laser corneal surgery, thus, there are a few hundreds and thousands of dissatisfied individuals. Furthermore, Waring 137 stated, “Unfortunately, published data on how many

98 patients wear spectacles and contact lenses after refractive surgery is almost nonexistent. A remarkable indictment of clinical reporting from the refractive surgical community, since the most importance criterion of success for patients who have refractive surgery is freedom from corrective lenses” (p. 213). Al-Kaff 133 reiterated, “One of the most underestimated aspects of refractive surgery in published reports is the patient’s own personal perspective.” (S459). Al- Kaff concluded that, “Additional studies are needed to assess the patients’ perspectives and to grade their satisfaction. This may elicit additional criteria that may be correlated with their motivation and expectations. Furthermore, proper patient selection and preoperative education most likely result in a higher level of patient satisfaction” 133 (S460).

Few studies have examined the patient’s perspectives. Fichte and Bell 128 sought to answer one fundamental question: “Were the patients satisfied with the results of their treatment over all, despite difficulties they may have had in any particular area?” (p. 269). The authors admitted that the questions in their survey were deliberately broad and open to different interpretations. The authors wanted to simulate what the patients would say if a friend asks about it without first highlighting any problems.

Gimbel et al. 21 found that 92% of patients were satisfied, and identified five factors that influenced patient satisfaction: uncorrected visual acuity, the need to wear contact lenses for residual refractive error, night driving problems, vision in dim and artificial light, and visual symptoms including general light scatter, halos, and haze effect. Limitations of this study were that the scales used were only “overall”, and the findings were not specific enough to provide useful information. The study used “rating of vision”, and it is not clear which type of vision the authors or the patients were referring to. Lastly, the magnitude and the effect of “visual symptoms” were not sufficiently addressed.

Kahle et al. 129 found that “to improve vision” was ranked the most important reason for having the surgery, followed by “better vision in sports and job” and “looking better”. In their study 74% of the patients no longer required corrective lenses. Halos and night driving problems were ranked the worst visual problems, followed by reading and diurnal vision changes. While 75% of the patients reported improvement in their lifestyle, 21% reported no change, and 4%

99 got worse; 85% were satisfied with the overall results, 12% claimed dissatisfaction. Surprisingly, 100% of the patients stated they would have PRK again, and 96% would recommend it to their friends. The authors concluded that even the dissatisfied patients must have gained some benefits. A limitation of this study is that “vision in general” was used, which is too unspecific to generate useful information. “Quality of life” was used, but there was no opportunity for patients to indicate what aspect of their life had changed. Also, dissatisfied patients were not given the opportunity to express why and/or what they were dissatisfied.

Some interesting anomalies arise from the above studies. For example, in Fichte and Bell’s 128 study, the data suggested that two patients were very satisfied with their result and yet had noticed no benefit gained. Kahle et al. 129 reported 12% of patients unsatisfied, but 100% of the patients stated they would have the procedure again and 96% said that they would recommend the procedure to a friend. Fichte and Bell 128 (p. 269-270) suggested, “The results reflect the psychosocial factors that influence the decision-making and treatment evaluation processes of the patient. The findings and the anomalies in those of Kahle et al. illustrated the dangers inherent in outcome studies. Furthermore, this highlights the importance of true informed consent. The only way of achieving any level of satisfaction in a patient with a less than perfect refractive result is to give thorough counselling before the treatment. If all risks, benefits, and possible outcomes are thoroughly understood along with relative probabilities, patient satisfaction levels with what is normally a very successful procedure, should improve.” McGhee et al.130 pointed out that the studies so far had failed to break the measures of satisfaction down into specific components of care, thus limiting the amount of useful information obtained. Satisfaction studies are not merely for the purpose of reassuring the practitioner that a specified number of patients are “satisfied” but should rather form the basis for critical analysis and improvement of service. Satisfaction is not one-dimensional; the complexity of the relationships between patient education, expectation, service delivery, and operative outcome must be carefully analyzed. In order to identify areas of dissatisfaction, one must ask much more specific questions. It frequently transpires that although patients are generally satisfied with the eventual outcome of a treatment episode, they are not happy with certain subcomponents of the service or treatment, such as, delayed recovery, or discomfort of

100 the procedure. McGhee et al. 130 found that 96% of patients were satisfied, and did not find any correlation between pre- and post-operative myopia, or failure to achieve 6/12 unaided acuity and levels of patient satisfaction. However, a weak correlation was identified between the following variables: pre-operative myopia greater than -6.00 diopters and greater reliance on spectacles post-operatively, patients with unaided visual acuity less than 6/12 post-operatively and the pre-operative desire to have PRK to be “free from glasses”, and satisfaction with the speed of improvement of vision and achievement of goals for which the procedure was undertaken. The authors stated (p. 878), “Although it might be reasonable to conclude that a less good unaided visual acuity might be more likely to result in dissatisfied patients, preoperative education and counselling to set realistic outcomes, and the patient’s underlying expectations are also major components in determining patient’s final assessment of the success of the procedure.” 130 This study was better formulated in evaluating more specific patient perspective issues, but rather than trying to establish the relationships between variables, perhaps the authors should have acknowledged the fact that only four out of the total 90 patients expressed dissatisfaction, and with such disproportional data between satisfied and dissatisfied patients, it is impossible to statistically demonstrate any meaningful quantitative analysis.

Brunette et al. 135 designed the first validated psychometric instrument specifically oriented toward the assessment of quality of vision. They found that satisfaction scores, acuity and refraction were not as closely linked as expected. The authors felt glare, night vision, and night driving problems influenced satisfaction negatively. They hypothesized that perhaps patients simply adapt to their new eye condition and tolerate these night visual symptoms, and suggested that the level of progressive adaptation could be assessed by re-administration of the survey on several occasions after the surgery. Until these problems can be address or treated, patients should be informed thoroughly before surgery. They suggested that future research should include pre- and post-operative patient self-assessment, as well as functional evaluation of glare, contrast sensitivity testing, objective quantification of the optical quality of the eye such as optical aberration measurements, and driving simulation.

101 Although the majority of post-PRK patient satisfaction studies have slowly become more patient-focused, patient satisfaction evaluation still seems to be secondary to technical concerns and clinical outcome measures, and have tended to use only measures of overall satisfaction with the exception of a few studies. 130,135-136 Although all the studies in this review have reported a high percentage of patient satisfaction, they have also reported a number of unwanted signs and symptoms. The majority of the studies rely on the improvement of surgical techniques and instrumental technologies to improve the unwanted signs and symptoms. However, the more sophisticated the procedures become, the higher patients’ expectations, thus the more challenges there are to achieving patient satisfaction.

Patient satisfaction with LASIK . There was no study which evaluated patient satisfaction with LASIK until 2000, when McGhee et al. 136 reported a study of 48 highly myopic patients ranging from -7.00 diopters to over -10.00 diopters. They found that the LASIK patients were statistically more satisfied with speed of visual recovery, overall improvement in quality of life, achievement of goals, UCVA and overall satisfaction with the final outcome compared with PRK patients.130 They recognized the limitation of a study with only 48 patients, but most patients reported functional improvement across the spectrum of visual tasks assessed, and 8.8% reported difficulty with nighttime driving. The authors reported the highest (98%) level of patient satisfaction compared to previous studies, 128-135 despite the fact that 32% of the eyes did not achieve UCVA of 6/12 or better. They speculated that this finding might be due to extensive pre-operative counselling and written information to set realistic expectations. The authors recommended that the ophthalmological community should move away from using only two objective measures, UCVA and residual refractive error, as the benchmarks for assessing the outcome of refractive surgery. They concluded that this and many previous studies did not assess daily functioning pre- and post-operatively, and thus the true impact of improvement from the surgery could not be identified. Therefore, there is a need to assess patients’ clinical results along with a better developed questionnaire with questions targeting the quality of vision in order to evaluate the reasons for subtle dissatisfaction.

102 3.13 Why Is it Appropriate to Measure Patient Satisfaction in Those Who Have Had LASIK Surgery? Throughout this chapter, the importance has been established of measuring patient satisfaction with medical care and treatment outcomes. Also, it is very much a part of current rhetoric in health care to include patient satisfaction not only as part of the evaluation of health care quality, but also due to increasing competitiveness among service providers. The measurement of patient satisfaction to some extent has become a tool for the modern marketing in this and other fields of medical care.

More specifically, from a clinical point of view, RK is one of the earlier refractive procedures, and the PERK studies have provided us with a great deal of knowledge about not only the surgical outcome but also patient perspectives of the procedure. By the early 1990s, laser refractive surgery such as PRK subsequently evolved to LASIK as an alternative to RK. Like RK, PRK and LASIK have been popularized by the demands of individuals with myopia, hyperopia and/or astigmatism. From a surgical perspective, PRK and LASIK received scrutiny similar to that for RK in the early stages of their debut. From the patient perspective, PRK and LASIK, especially PRK, was given the same “judgment” as RK, that is, individuals electing to have the PRK were labelled “risk takers”. This was illustrated by Erickson et al., 140 who attempted to demonstrate that patients electing to have PRK were different from the general population in that they had “information processing preferences for the auditory modality in a global associative versus detailed, sensory-oriented style with adaptability and risk-taking personality characteristics” (p. 272). The authors thus suggested that high patient satisfaction with PRK was biased by pre-surgical self-selection based on underlying information processing patterns and personality characteristics. They postulated that the satisfaction findings were “implicit in the theory of cognitive dissonance, which predicts that once a person chooses it, he/she undergoes a change in behaviour, and attitudes must change to be consistent with the behaviour. In other words, ‘If I chose to do it, it must be worth doing and that any outcome is worthwhile’” 141 (p. 272). These findings sparked much debate. Powers 140 felt that the conclusion was too strong, given the fact that both cognitive style and personality measures have severe limitations. Bourque 125-127 questioned to what extent personality differentiated those who elected PRK from those who did not? Does the theory of cognitive

103 dissonance really explain the high levels of patient satisfaction, which were not tested in the study? Bourque was concerned that the tests chosen overlapped and could limit the findings. He concluded that it was unlikely that a significant difference in personality existed between those who did and did not elect PRK. More to the point is the extent to which patients who choose to investigate PRK differ from comparable myopes who do not seek such information. Also, the study did not provide clear support for the conclusion that individuals who elect PRK are more likely to be “thrill seekers”. It should not be concluded that patients who seek refractive surgery are homogeneous on any characteristic. “We were wrong in 1980 to assume that anyone who sought RK was crazy, we would be wrong again in 1995 to assume that all individuals who elect PRK are risk takers or are auditory-oriented” 140 (p. 278).

As with RK, there was extensive evaluation of PRK and LASIK, and extensive knowledge was gained from these findings. Because LASIK evolved from PRK, from a surgical perspective LASIK is considered to be superior. Perhaps for this reason, researchers have been less driven to assess patient satisfaction with LASIK, thus less literature is available. However, as stated throughout this chapter, treatment outcomes defined by professionals may differ from those defined by patients. Also, subjective or patients’ impressions are equally, if not more important, because patient satisfaction ultimately influences both the future and the popularity of the procedure. So far, most of the satisfaction studies in LASIK patients have been global, generalized, and did not use a patient-centred approach. They have provided limited detail of subjective aspects such as the patient’s viewpoint about having had the procedure, whether the procedure had achieved their goals, what their expectations had been, issues such as the quality of vision in everyday situations, whether they were experiencing symptoms and where they were having the most difficulty. The literature related to measuring patient satisfaction indicates the need to move beyond global measures because they provide little information about what patients are thinking, and do not allow any understanding of where improvement is needed.

Lastly, refractive surgery as a subspecialty field of ophthalmology has become far more competitive than any fields of medicine to date, due to the new source of income from patients’ demands. Thus, the aggressive nature of competition for patients has been

104 intensified. Refractive patients have become far more sophisticated about the type of care they receive, so providers need to be more attentive to their needs and concerns. Because refractive surgery such as LASIK is an elective surgery, one can label this kind of patient as a patient- customer. As Mannis et al. 142 (p. 9-10) have stated, This is a new class of patients who come to an ophthalmologist as much in the role of consumers as patients and with specific expectations and demands. Seeing a new source of income, ophthalmologists have increasingly turned to advertisement of their services in all forms of media. The seriousness of ethical issues surrounding self-promotion and truth in advertising have been of concern to the ophthalmology community at large world wide.

In view of this, perhaps the most straightforward way of thinking of patient satisfaction with LASIK is from a marketing perspective. One can think of patients as customers and the medical care profession or organizations as providers of services. If the providers of care are competing for patients and patients choose providers on the basis of satisfaction, then successful marketing will depend to a great extent on the ability of the provider to maximize patient satisfaction. Only a few years ago such a statement would have sounded insensitive and superficial. However, it is quite evident that the trend of refractive surgery such as LASIK is heading in this direction. With the current supply of physicians, and the entry of for-profit organizations into the marketplace, providers are becoming increasingly interested in marketing approaches. They use patient satisfaction surveys as a tool of advertisement to compete for market share and referral. As marketing plays a larger role in the delivery of care, it is important to separate evaluations that identify the need for improvement motivated primarily by marketing considerations from those motivated primarily by concern about quality of care. From a scientific perspective, investigators must assess the patient satisfaction with the outcomes not only concerned about the relationship associated with patient satisfaction, but assess patient satisfaction with physical outcomes such as increases in functioning, achieving the desired quality of life, integrate it as part of the quality of care and ultimately achieve higher patient satisfaction.

105 Therefore, it is not only appropriate, but it is essential to find better ways to understand how patients evaluate satisfaction for those who have undergone LASIK surgery, because there are still issues remaining to be investigated and explored. There is still a need to better focus on patients’ perceived treatment outcomes and to identify factors that patients consider to be important. Perhaps such findings will not only help to better prepare future patients to set realistic expectations of the likely visual outcome, but also identify functional results that may influence levels of satisfaction.

3.14 Why Not Use Conventional Established Questionnaires to Measure Patient Satisfaction in LASIK Patients? Based on the literature, 110-113,120-127 all the studies so far have adopted some or part of validated questionnaires designed by other researchers, but they have all modified them and/or used additional items to make the questionnaires more specific to the population being investigated. Furthermore, the literature highlights the fact that investigators have been cautioned against the use of standardized measures because they are not designed to capture context-specific dimensions of the individual studies. Even though standardized measures are easy to use, allow for comparisons across settings and studies, and have often been through the rigors of psychometric testing for reliability and validity, what “validity” in this context really means is not clear. There are at least two major problems. The first is that some patients’ descriptions of their health care experiences appear inconsistent with their reports on satisfaction measures, which emphasizes the need for clarification about the association between perceptions, experiences and expressions of satisfaction. The second problem is the ambiguity about the meaning of satisfaction itself. This is the main weakness in this field of investigation, particularly because of the way in which the meaning influences research design, interpretation of measures and findings. However, the literature provides an opportunity to compare methods and to formulate some principles that measures of patient satisfaction have developed. According to Carey, 143 “a single generic survey will not meet all the needs. You will need to acquire a set of surveys uniquely designed for the individual purpose to meet its needs.” (p. 20). All researchers in the literature have done their best to design questionnaires to meet their study’s needs. Likewise, in order to evaluate patient satisfaction with a treatment

106 outcome such as LASIK, conventional, established questionnaires are neither appropriate nor sufficient to measure patient satisfaction.

The LASIK procedure involves operating on a perfectly healthy individual, not only with healthy eyes, but with perfect eyesight with their prescription glasses and/or contact lenses. The value and justification for the indication of surgery is entirely different from that of cataract patients. The SF-36 health survey questionnaire or the VF-14 Index of Visual Functioning constructed for cataract patients simply do not apply to LASIK patients. Perhaps the PERK studies’ questionnaires are more relevant, since RK patients seem to have the closest similarity in characteristics to individuals who undergo LASIK. The PERK studies focused on functioning, impairment, expectations of individuals with refractive error, and satisfaction with the surgery. However, the surgical techniques for RK and LASIK are different. In particular, RK causes continuous corneal curvature decompensation which results in fluctuation of vision long after the procedure has taken place. Therefore, many of the questions in the PERK studies targeted this issue and its consequences. Part of the PERK studies had a patient satisfaction index, which addressed clarity of vision and general satisfaction with the surgical results, but even this satisfaction index used only global measures. As the literature has highlighted, 106,114,143,144 global measures are no longer considered to be acceptable, as they provide insufficient information, specifically direction for improvement. It is clear that the investigators in the PERK studies were more concerned with the safety and efficacy of the procedure, and oriented the investigation from the surgeon’s perspective. They were not focused on trying to understand how they could improve patients’ satisfaction.

Perhaps questionnaires from PRK studies could be used, since LASIK evolved from PRK. PRK patients have the same refractive status, vision profile, bio-physiological properties and similar healing process as the LASIK patients, also sharing the same interest within the ophthalmology community as well as the general public. However, the literature review related to patient satisfaction with PRK and LASIK has demonstrated that only a few studies contain useful information. The earlier studies in particular were based on very general measures only, not specified to types of functional tasks which require different level and

107 quality of vision. There is limited information demonstrating any attempt to understand or improve patients’ satisfaction.

By the late 1990s, as laser refractive surgery centres proliferated as a direct result of the public’s enthusiasm for refractive surgery, Mannis et al. 142 stated that this had given rise to a series of important ethical and professional issues in ophthalmology. Perhaps for these reasons, some studies provide little information to understand how patients evaluate satisfaction; instead, they appear to be designed to reassure surgeons of the procedure’s popularity and the potential market trend. For example, Orr et al. 145 reported that the aim of their study was to identify the factors that most influenced patient choice of an excimer laser treatment centre and those most likely to deter patients from selecting a particular centre. Ucakhan et al. 146 assessed the characteristics of a myopic patient population applying for refractive surgery in order to determine the potential market for myopic refractive surgery. It is clear, from the literature that there are investigators who have assessed PRK and LASIK, were genuinely concerned about the safety and efficacy of the procedure. They also would like to understand how patients perceive the success of the surgery and how well patients function in their daily life post-operatively. However, other investigators appear to be driven by financial motives. Therefore, it is important to learn from past studies, refine the assessment of patient satisfaction in LASIK, focus on patients’ perceived treatment outcomes and design a questionnaire to identify factors that patients consider to be important. There is a need for a longitudinal study, using a repeated measures design to detect changes over time to monitor the surgical stability of the procedure, the subtle subjective changes and the functional ability of patients long after the procedure has taken place. There may be a need for both quantitative as well as qualitative analysis to differentiate between patients who use visual acuity as a criterion of satisfaction with the surgery and those who use other criteria to make this judgment. By so doing, one can address the shortcomings identified in previous studies.

Consequently, the key aspects of this study’s investigation are a repeated measure design to follow a cohort of subjects to detect changes over time. Furthermore, a control group (non- LASIK subjects) is included in the study, not only to illustrate the effectiveness of LASIK as a surgical procedure, but also to compare and demonstrate ocular symptoms, visual abilities and

108 visual difficulties that are common between LASIK and non-LASIK patients. This in turn may identify factors that are pre-existing and factors that may exacerbate post-LASIK and may contribute to patient satisfaction.

3.15 Research Questions In view of the literature review, the aim of this study is to investigate patient satisfaction and its relationship to the clinical outcomes and patient characteristics. This aim was operationalised as 36 research questions, listed below. Some of these questions are more central to the research aim and they are marked with an asterisk: A. Clinical data evaluation 1. From an efficacy perspective, what level of uncorrected distance visual acuity can LASIK achieve? 2. How stable is the post-operative uncorrected distance visual acuity? 3. How do subjects’ pre-operative BCVA compare to their 3 months post-operative UCVA? And how does it compare to the BCVA at baseline and 3 months in the control group? 4. From a safety perspective, what level of best-corrected distance visual acuity can LASIK achieve? 5. How stable is the post-operative best-corrected distance visual acuity? 6. How does subjects’ pre- and 3 months post-operative best-corrected distance visual acuity compare to the BCVA at baseline and 3 months in the control group? 7. For monovision corrected subjects, what level of uncorrected near visual acuity can LASIK achieve? 8. How stable is the post-operative uncorrected near visual acuity? 9. Repeated measures study is known to have different response rates in each survey. Thus, is there any significant difference in post-operative uncorrected distance, near visual acuity and best-corrected distance visual acuity between subjects who returned for more than one survey and those who returned for only one survey? 10. From an accuracy perspective, how does the intended surgical goal compare to that achieved? 11. What are the ranges of residual refractive errors? How stable are they?

109 12. Repeated measures study is known to have different response rates in each survey. Thus, is there any significant difference in residual refractive errors between subjects who returned for more than one survey and those who returned for only one survey? B. Subjective or patient satisfaction evaluation 13. How did the subjects learn about LASIK, why and what did they want to achieve from having LASIK? 14. * For questions that are comparable between the treatment and control group, how do subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, overall quality of life, treatment outcome and satisfaction of treatment) compare between the two groups? 15. * From the treatment satisfaction perspective, would the subjects recommend one form of treatment over the other when compared between the treatment and control groups? 16. * Again, from the treatment satisfaction perspective, how do the satisfied and dissatisfied subjects compare between the treatment and control groups? 17. * From a stability perspective, are there any significant changes in the subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment) over time? 18. Repeated measures study is known to have different response rates at each survey. Thus, is there any significant difference in the subjects’ responses to the questionnaire between subjects who returned more than one survey and those who returned only one survey? C. To establish relationships between the clinical and subjective/patient satisfaction variables for the treatment group 19. * Is there any correlation between the uncorrected distance and near visual acuity achieved post-operatively and subjects’ satisfaction? 20. * Is there any correlation between the change from pre-operative best-corrected to post-operative uncorrected distance visual acuity and subjects’ satisfaction? 21. * Is there any correlation between the change from pre- to post-operative uncorrected distance visual acuity and subjects’ satisfaction? 22. * Is there any correlation between post-operative residual refractive errors and subjects’ satisfaction?

110 23. * Is there any correlation between post-operative uncorrected binocular visual acuity achieved and subjects’ responses to the questionnaire regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment? 24. * Is there any significant difference in subjects’ responses to the questionnaire between subjects who were satisfied and dissatisfied? 25. Is there any significant difference in subjects’ responses to the questionnaire between those who no longer required and those who still required glasses and/or contact lenses post-operatively? 26. Is there any significant difference in satisfaction between male and female subjects? 27. Is there any significant difference in satisfaction between subjects who are younger than and those who are older than 40 years of age? 28. Is there any significant difference in subjects’ responses to the questionnaire between subjects who are younger than and those who are older than 40 years of age? 29. Is there any significant difference in satisfaction between myopic and hyperopic subjects? 30. Is there any significant difference in post-operative uncorrected distance and near visual acuity between myopic and hyperopic subjects? 31. Is there any significant difference in subjects’ rating of their uncorrected distance and near visual acuity (Question 7a & b in the questionnaire) between myopic and hyperopic subjects? 32. Is there any significant difference in subjects’ responses to the rest of the questionnaire between myopic and hyperopic subjects? 33. Is there any significant difference in satisfaction between subjects who had mild and those who had severe refractive errors pre-operatively? 34. Is there any significant difference in satisfaction between emmetropic and monovision treated subjects? 35. Is there any significant difference in satisfaction between subjects who did not and those who required an enhancement? 36. * Are there variables in the study that can be use as predictors to explain patient satisfaction?

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C H A P T E R 4

The Development and Construction Processes of The Questionnaire Chapter 4

4.0 Development and Construction of the Questionnaire As stated earlier, the definition of success in refractive surgery has essentially been based on traditional clinical criteria such as uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), residual refractive error, and lines lost or gained after the procedure. The importance of quality of vision and patient satisfaction has only begun to be quantified and treated as an integral part of evaluating treatment outcome. Unlike any other field of ophthalmology, refractive centres have generated a wealth of information about LASIK, its technologies, and the surgeons’ credentials to compete for market share. Thus, most LASIK patients would have certain levels of knowledge before they choose a specific surgeon and centre. It is important to understand how these patients evaluate the success of the procedure. The literature indicates that patient satisfaction is a complex and multidimensional parameter. 40,44,106,110,113,126,127 It is influenced by the subjective quality of vision, personal expectations, personality type, coping mechanisms and more. 73,147,148 The challenge is to design a sensitive psychometric instrument that takes these parameters into consideration as well as meeting the commonly accepted norms of validity, reliability, acceptability and interpretability. The development process of the questionnaire was twofold: an exploratory expedition to gather information from previous refractive surgery studies (as outlined in Chapter 3), and exploratory interviews with ex-LASIK patients.

4.1 Exploratory Interviews with Ex-LASIK Patients Exploratory interviews were conducted with a small number of patients who had had the LASIK procedure and had interactions not only with the consultant surgeon but also with all levels of staff in the clinic, in order to provide opinion on all aspects of the treatment experience. The purpose of this process was to gather useful information, extract specific examples from the patients’ experiences through the process of having the procedure, and identify key issues that were important to the patients, which might lead to satisfaction or dissatisfaction. This process was used to provide a better understanding of the way patients defined and assessed the process of having the procedure, their expression of how successful

112 the treatment was, and how effective the services provided were. This knowledge was used to facilitate the development of the questionnaire.

The transcripts gathered from the exploratory interviews with the ex-LASIK patients went through content analysis and generated areas that were important. They were honesty, ophthalmologist’s experience and credentials, information about diagnosis and prognosis, and explanation in clear simple language, especially about the operation and its side effects. These were among the top ranking items, and this may reflect the fact that in the recent years, as refractive centres became more competitive for market share, patients have been bombarded with advertisements making claims such as being the best surgeon, or having done a certain numbers of cases. This is one of the ethical and professional issues described by Mannis et al.142 (see Chapter 3). The general public sometimes resorts in contacting a professional governing body such as the Royal Australian and New Zealand College of Ophthalmologists (RANZCO). Traditionally, it has been considered unethical for medical professionals to advertise their services. In Australia, RANZCO has attempted to intervene by setting guideline and having refractive centres restrict their advertisement to stating facts about their credentials and their centres.

In the interviews, the two most frequently asked questions by interviewees related to technology and surgeon’s experience. This reflects the competitiveness among refractive centres, each claiming it has the best laser or the latest technology to provide the best visual outcomes. Some refractive centres indirectly teach their inquirers the probing technique to ask technical questions such as: How many cases has the surgeon performed? What is the worst case the surgeon has encountered? How did he/she handle it? What laser and keratome does the surgeon use? By doing so, patients are supposed be able to judge which surgeon is more experienced, who uses up-to-date technology, and who best answers their questions or concerns.

Level of pain or discomfort, and the rate of visual recovery were the next most important issues, due to the fact that most patients were professional men and women who would like to resume to their normal working schedule as soon as possible. Unlike other ophthalmic

113 procedures, LASIK is known for its rapid visual recovery. Thus patients commonly have the consultation and procedure on the same day, and discharge after the day 1 follow-up. The patients are then monitored by optometric co-management. This arrangement has created number of clinical and ethical issues, which will be discussed in Chapter 5.

Listening, addressing concerns, and addressing needs of patients were the other important issues. As mentioned before, most LASIK patients have some prior knowledge about the procedure, and have some idea what they wish to achieve from having the procedure. Clinically, whether the patient’s goal is achievable safely varies. Determining whether the patient is a suitable candidate appears to be straightforward, but sometimes can vary depending on the surgeon’s conservativeness or confidence, or which refractive procedure is the surgeon’s preference. Thus technical expertise advice from surgeon to surgeon may in a minority of cases differ. In other ophthalmic conditions the surgeon tends to take charge of the treatment, whereas with LASIK, patients would like to be involved in the decision-making regarding their treatment. Therefore, communication to reach totally informed consent between the patient and surgeon is extremely important, in fact the need has reached a new height due to the higher incidence of litigation in refractive surgery.

The ex-LASIK patients emphasized the importance of how and when information was given regarding what to expect immediately after surgery. They felt it was difficult to follow instructions immediately after surgery while their eyes were watering and they were feeling drowsy from the effects of the relaxing medication given prior to the surgery.

Lastly, apart from the ophthalmic surgeon, the attitude and knowledge of the auxiliary staff were also important. It seems that the knowledge and the level of care provided by the auxiliary staff not only helped to alleviate patients’ concerns, but also reflected the overall competence and technical confidence of the refractive centre as a whole. This is illustrated from patients’ comments such as, “I was impressed with very competent and caring support staff who readily attended to my every need from initial contact to the last visit.” “Through each step of the process, my confidence grew and my nervousness diminished.” These interview findings were more comprehensive than those reported in any previous studies, such

114 as by Orr et al. 145 and Dawn et al. 149 In view of the findings, not only were the information obtained in the exploratory interview used to formulate the wording of the questions, but all the issues were addressed in the design of the study’s questionnaire.

4.2 Composition of the questionnaire Questions 1 to 5 of the questionnaire were simply designed to establish patients’ characteristics, profiles and their goals for having LASIK. They were as follows: 1. How did the patient first learn about the LASIK procedure? 2. Who referred the patient? 3. What was the patient’s PRIME objective for having the surgery? 4. What were the patient’s other reason(s) for having the surgery? 5. What was the patient’s PRIME desired end result? These questions were open-ended, designed to allow patients to express their individual circumstances and to gain psychological, sociological information and establish patient profiles.

Ideas for some question themes were adopted from the previous studies 21,128-136 , but much of the attention was focused on designing new questions that were carefully framed, with each consisting of a single theme, and clearly laid out to make it easier for patients to look at, process what information each question sought, and answer without ambiguity. The aim was to elicit how patients evaluated each theme of the questionnaire, including experience of the procedure, level of discomfort, areas of difficulty, visual outcomes, and perceived treatment success. Therefore, Questions 6 and 7 were designed as follows: 6. Do you have any Pain 0 1 2 3 4 5 Irritation 0 1 2 3 4 5 Glare 0 1 2 3 4 5 Dry eye 0 1 2 3 4 5 NOTE: 0 = none 1 = mild 3 = moderate 5 = severe

115 7. How do you rate the level of vision without glasses or contact lenses in the following daily activities? NOTE: 1 = inability to perform the activity due to visual difficulty 10 = no problem Distance vision 1 2 3 4 5 6 7 8 9 10 Near vision 1 2 3 4 5 6 7 8 9 10 Daytime driving1 2 3 4 5 6 7 8 9 10 Night driving 1 2 3 4 5 6 7 8 9 10

There is a general consent from the literature 128-136 that patients themselves are the best people to assess functional ability in their daily activities, subtle changes or improvement over time. Therefore, these aspects were carefully worded and formatted into Question 8 as follows: 8. Are there any changes in your vision which affected or improved your ability to perform the following tasks? much worse no better much worse change improved Physical activities [ ] [ ] [ ] [ ] [ ] Social/recreational activities [ ] [ ] [ ] [ ] [ ] Home activities [ ] [ ] [ ] [ ] [ ] Work activities [ ] [ ] [ ] [ ] [ ] In this format, the wording of the questions not only avoid acquiescence bias, but the quantification is clear and specific to the individual activity.

Question 9 dealt with an important issue of having the procedure. If the goal in having the surgery was to do away with glasses and/or contact lenses, and if patient(s) still need to wear glasses and/or contact lenses post-operatively, would they consider it a failure from the treatment outcome perspective? Furthermore, as highlighted by Waring III, 137 there is little data regarding patients wearing any form of visual aid after refractive surgery. With this in mind, question nine was designed to capture this important aspect as follows; 9. Do you need to wear any glasses or contact lenses now after the surgery? If yes, for what purpose? ______

116 This question was specifically designed to be an open-ended question to allow patients to express their opinions and how they felt about having to wear glasses and/or contact lenses again post-operatively. With the same line of thought and argument, Question 10 was designed to elicit any further feelings of dissatisfaction from the patients. Thus, Question 10 was designed also as an open-ended question, as follows: 10. If any, what is the ONE MAIN symptom that you are experiencing? ______If you have more than one symptom you may list others. ______

Question 11 addressed the overall effect on the patient’s quality of life after having had the LASIK procedure. According to the literature in patient satisfaction studies, 110-113,120 quality of life defines functional well-being. Therefore, there is no doubt that the patient’s quality of life after having had the LASIK procedure is one of the paramount parameters that had to be included in the survey. The reason for this question to follow Questions 9 and 10 was if the patients remained dependant on glasses and/or contact lenses, or if they were dissatisfied with the quality of vision post-operatively, it could have a negative effect on their quality of life, and here patients were given another opportunity to express how they felt. Thus, Question 11 was: 11. In your opinion, has the operation had any effect on your overall quality of life? (please tick one) much worse worse no different better much improved [ ] [ ] [ ] [ ] [ ]

On the basis of the exploratory interviews with the ex-LASIK patients, it was clear that the patients emphasized the importance of communication, how and when the information was given by their treating ophthalmologist and the auxiliary staff. The patients stated that there was need for more information about the level of pain expected immediately after the surgery, and more detailed information about the healing process and visual recovery. Also, they felt it was difficult to follow instructions immediately after surgery while their eyes were watering

117 and they were feeling drowsy from the effect of the relaxing medication given prior to the surgery. Therefore, Questions 12, 13 and 14 were closed-ended questions designed to quantify the amount of information given about the procedure prior to the surgery, information as what to expect immediately after the operation, and information given regarding after-care. These questions had a 3 and 5-point Likert scale response format so that quantification could be established, as follows: 12. Was enough information given to you about LASIK prior to the surgery? (please tick one) almost nothing not enough satisfactory good excellent [ ] [ ] [ ] [ ] [ ]

13. Was enough information given to you as what to expect immediately after the surgery? (e.g. pain, glare, blur) (please tick one) almost nothing not enough satisfactory good excellent [ ] [ ] [ ] [ ] [ ]

14. How much information were you given regarding the regime of using eye drops, and medication? (please tick one) none some complete [ ] [ ] [ ]

The next two questions were vital to the investigation of patient satisfaction, because not only did they identify how the patient perceived the treatment outcome, but the investigator could compare the clinical results with the patient’s perspectives, which in turn may influence the future of LASIK as a surgical procedure. These questions were designed to assess patients’ self-perceived ratings of how successful the surgery was, and whether the outcome met their expectations. Thus, Question 15 and 16 were as follows:

118 15. How would your rate the success of the surgery? (please tick one) very unsuccessful moderately unsuccessful moderately successful very successful [ ] [ ] [ ] [ ]

16. How do you compare your satisfaction now with your pre-operative expectations? (please tick one) [ ] surgery outcomes did not at all meet expectations [ ] surgery outcomes partially met expectations [ ] surgery outcomes met expectations [ ] surgery outcomes slightly exceeded expectations [ ] surgery outcomes greatly exceeded expectations

Questions 17, 18 and 19 were designed as open-ended questions that gave further opportunity for patients to express any subcomponent(s) of dissatisfaction, as there is evidence in the literature that patients may be happy with the overall outcome of the procedure, but they may be dissatisfied with certain subcomponents of the service or treatment or certain aspect of the quality of vision. These questions allowed patients to describe “the subtle ‘but…’”, rather than confining their responses with “choose the one that best describes your experience”. As shown in the results the questions wording tended to prompt answers of just a few words. Thus, Question 17, 18 and 19 were: 17. Now that you have undergone the surgery, knowing what you know now, would you still have the surgery? ______18. Would you have the second eye done if required? ______19. Would you recommend LASIK to some-one else? ______

119 Lastly, one of the important reasons for having the procedure was to improve vision or quality of vision, which in turn improves quality of life. Therefore, the survey would not be complete without a question assessing the comparison of vision before and after the surgery. The final question in the questionnaire was as follows: 20. Are you more satisfied or less satisfied with the vision you have now compared to the vision you had with the previous correction with glasses and/or contact lenses? (please tick one) Much more satisfied somewhat more satisfied about the same [ ] [ ] [ ] somewhat less satisfied less satisfied [ ] [ ]

Many steps were taken to reduce the time and effort required for patients to complete the questionnaire. The questions were designed to be simple, short and to ensure quick and easy understanding. Also, the questionnaire used direct measures combining closed- and open- ended questions to gain a fuller understanding of patient satisfaction with specific medical encounters. Double negatives, technical or medical terms were not used. Ambiguous words or phrases were not used, to prevent unintended interpretations which might cause unintentional responses and produce spurious data. Each question contained only one theme or aspect, to prevent confusion as to which part of the question the patient wanted to respond affirmatively or negatively to. Questions that assessed satisfaction with care were designed to be separate from those assessing satisfaction with treatment outcomes, as even though they might contribute to each other, they represent distinct phenomena that are more validly conceptualized from different perspectives. Separation minimized the contamination of one by the other. Lastly, the questionnaire was designed to minimize emotional artefacts or memory recall by patients and to maximize the facts. The questions were presented in a logical order which corresponded to the events experienced by patients.

4.2.1 The Pilot Study In preliminary testing, the questionnaire was piloted with a small group of clinicians, administrative staff, and nurses, staff with whom patients communicated and who were part of

120 the care provided. The questionnaire also was piloted with a small group of refractive patients who returned for their post-operative review. The questionnaire was administered after patients finished their post-operative review with their surgeon, as outlined in the study methodology. The feedback from these pilot study subjects was important as they represented the patient profiles of the main study. The results showed the questionnaire to be clear and precise, as reflected by the responses given. One subject found Question 20 to be too general, as the exact wording of the question was “Are you more or less satisfied with the vision you have now compared the vision you had with the previous correction with glasses and/or contact lenses?” With this feedback the question was reworded to read “Are you more satisfied or less satisfied with the vision you have now compared to the vision you had with the previous correction with glasses and/or contact lenses?” A few incorrect spellings and grammatical errors were revealed, which were immediately corrected. One subject complained that the questionnaire was long, but after a thorough review it was decided that all the questions and their subcomponents were important aspects of the study, and it should not be shortened any further. Thus, the questionnaire remained without any further changes.

4.2.2 The Final Version of the Questionnaire The final version of the questionnaire consisted of 20 questions; 10 open-ended questions, one of which had two sub-components, 10 closed-ended questions, three of which had four sub- components and were in 5- and 10-point Likert scale response formats. The remaining seven closed-ended questions were in a 3-, 4- and 5-point Likert scale response formats. For all of the closed-ended questions and their subcomponents, the patients were instructed to tick or circle one response that best described their view. This response format was chosen in view of the literature 73 because it gave greater opportunity to express the precise nature of the patient’s views. Furthermore, the reliability of items increases as the number of response alternatives increases. For the exact wording of the questionnaire and the associated response options, see Appendix I.

4.2.3 Validation of the Questionnaire The formal psychometric properties of the questionnaire were assessed using the statistical package for the social sciences (SPSS version 10), (SPSS Inc., Chicago, IL, U.S.A.).

121 Reliability The property of reliability is assessed to ensure that measurements are free from random-error variance. In another words, each question should ask exactly what it is supposed to ask, and should produce a consistent response that is reproducible. There are three relevant forms of reliability: test-retest reliability, equivalent-form reliability, and internal consistency. Internal consistency reliability was chosen because it assesses the degree to which the items in a survey are measuring the same thing.

There are several methods to estimate the degree of reliability, which is generally reported as a coefficient between zero (no reliability) and one (perfect reliability). Cronbach’s alpha coefficient (ά) was chosen as it is the most common method. It is based on the average correlation of items within a test if the items are standardized. If the items are not standardized, it is based on the average covariance among the items. The questions in the survey were designed in such way that the scales were not the same, in fact they were in 3-, 4-, 5- and 10-point Likert scale format. Therefore, it was more appropriate to calculate reliability using “Z scores”, and there is evidence of discriminant validity. The result was interpreted as Cronbach’s alpha ( ά).150 There is no rigid rule for determining an acceptable level of reliability, but according to the criterion offered by Helmstadter, 152 for scales that compare groups a minimum of 0.5 is generally considered acceptable.

All 19 of the closed-ended questions in the questionnaire were selected for the internal consistency reliability analysis with 211 study subjects. The results showed that Questions 6a- d, and 14 had the lowest corrected item-total correlation. The Cronbach’s alpha for the overall scale was equal to 0.72. With these items removed and the reliability coefficient recalculated, the final Cronbach’s alpha was 0.77. (For the exact analysis see Appendix II.).

As mentioned earlier, test-retest reliability is another form of assessment. The test assumes that there is no change over time, which relates to one of the research questions evaluating whether LASIK as a surgical procedure provides a stable visual outcome. If this was the case, patients’ responses to the questionnaire would be stable over time. Therefore, test-retest

122 reliability was not calculated, simply because the condition and criteria of the test were inappropriate for this study.

Validity Validity refers to the degree to which a scale measures what it is designed to measure. Unlike indices of reliability, no one statistic provides an overall index of validity of scale scores. Validity can be assessed by several methods, called face validity, concurrent validity, predictive validity, content validity, discriminant validity and construct validity. Often, only some forms of validity can be assessed for any given instrument.

Of the forms of validity, construct validity is the most comprehensive. It is often assessed by performing a factor analysis on a large number of survey responses. Factor analysis was not performed in the present study. Although the sample size of the present study was reasonably large, factor analysis is designed to work on samples containing thousands of cases, and is not recommended for samples below 200. 153

Most other forms of validity were not appropriate in the current study. Concurrent validity requires a gold standard measure against which to compare scores. No such measure exists. Similarly, discriminant validity requires an accurate measure of constructs related to, but distinguishably different from, the constructs assessed by the survey. Assessing predictive validity is problematic in a study which seeks to track changes over time. The only future behaviours which could be predicted would be the decision to have further LASIK treatment. Information relating to such decisions was either not useful, in the case of people who had had both eyes treated, or was too confounded with other clinical variables to provide accurate criteria against which to judge survey responses.

In the absence of post hoc statistical methods of assessing validity, the issue of validity was addressed by the methods of constructing the survey to establish content and face validity. Content validity was assessed by comparing the breadth of topics covered by the survey and two independent sources of information about the domain. These two sources were the content of previous surveys, and an analysis of the content of comments made by

123 respondents in the pilot study. Items were added to the survey until all relevant content areas identified from literature and the pilot study were covered.

Face validity is the weakest form of validity. In this study it was provided by using standardised question formats, such as Likert-style scales, and by following the recommendations of previous researchers.

4.3 Development and Construction of the Control Group Questionnaire As stated in the introduction, and in Chapter 3, one of the key aspects of this study was the inclusion of a control group (non-LASIK subjects). The purpose of the control group was not only to illustrate the effectiveness of the LASIK as a surgical procedure, but also to compare and demonstrate ocular symptoms, visual abilities and visual difficulties that were common between LASIK and non-LASIK patients. Comparisons could also be made of patients’ responses to questions about satisfaction issues. Did patients’ opinions of their vision simply change over time? A control group questionnaire was also constructed, containing similar key aspects to the treatment group questionnaire. The questionnaire was administered to non- refractive patients who had the same refractive profile, but did not undergo the LASIK procedure. The final version of the control group questionnaire consisted of nine questions: three open-ended questions, two of which had two sub-components; six closed-ended questions, four of which had four sub-components, and were in 4-, 5- and 10-point Likert scale response formats. For the exact wording of the questionnaire and the associated response options see Appendix III.

Question 1 of this questionnaire was simply to designed to establish the patient profile, whether he/she wore glasses and/or contact lenses, and for what purpose. 1. Do you currently wear glasses or contact lenses? If yes, for what purpose? (a) Glasses______(b) Contact lenses______

Questions 2 and 3 were designed to identify ocular symptoms with glasses and/or contact lenses. These questions were similar to the treatment group Questions 6 and 10, as follows:

124 2a.While wearing your glasses do you 2b.While wearing your contact lens do have any you have any Pain 0 1 2 3 4 5 Pain 0 1 2 3 4 5 Irritation 0 1 2 3 4 5 Irritation 0 1 2 3 4 5 Glare 0 1 2 3 4 5 Glare 0 1 2 3 4 5 Dry eyes 0 1 2 3 4 5 Dry eyes 0 1 2 3 4 5 NOTE: 0 = none 1 = mild 3 = moderate 5 = severe

3. If any, what is ONE MAIN SYMPTOM or ANNOYANCE that you are experiencing? ______If you wish you may list other symptoms or annoyances. ______

Question 4 was designed to allow patients to rate their level of vision with their current glasses and/or contact lens. It was similar to the treatment group Question 7, and is as follows: 4. How you rate the level of your vision with glasses and/or contact lenses in the following daily activities? NOTE: 1 = inability to perform the activity due to visual difficulty 10 = no problem Distance vision 1 2 3 4 5 6 7 8 9 10 Near vision 1 2 3 4 5 6 7 8 9 10 Daytime driving 1 2 3 4 5 6 7 8 9 10 Night driving 1 2 3 4 5 6 7 8 9 10

Question 5 was designed to allow the patients to report their functional ability in the last 6 months with the current glasses and/or contact lens. It was similar to the treatment group Question 8, as follows:

125 5. Think back to the time you last had your eyes examined (about 6 months ago). Are there any changes in your vision which have affected/improved your ability to perform the following tasks: much worse worse no change better much improved Physical activities [ ] [ ] [ ] [ ] [ ] Social/recreational activities [ ] [ ] [ ] [ ] [ ] Home activities [ ] [ ] [ ] [ ] [ ] Work activities [ ] [ ] [ ] [ ] [ ]

Question 6 was designed to allow patients to report on the effects of wearing glasses and/or contact lenses on their individual quality of life in the last 6 months. It was similar to the treatment group Question 11, as follows: 6. Think back to the time you last had your eyes examined (about 6 months ago). What effect has wearing glasses and/or contact lenses since then had on your overall quality of life? much worse worse no different better much improved [ ] [ ] [ ] [ ] [ ]

Question 7 was designed to allow patients to express how satisfied they were with wearing glasses and/or contact lenses. It was similar to the treatment group Question 20, as follows: 7. How happy are you that you need to wear glasses and/or contact lenses to achieve normal (or close to 6/6) vision? very dissatisfied moderately dissatisfied moderately satisfied very satisfied [ ] [ ] [ ] [ ]

Question 8 was designed to establish how many of the control group patients would elect to have laser refractive surgery if they were suitable candidates, as follows:

126 8. If money was not a factor, would you have chosen laser surgery to correct your refractive error (near or far-sighted)? Definitely probably unsure probably not definitely not [ ] [ ] [ ] [ ] [ ]

Question 9 was designed to establish how many of the control group patients would recommend glasses and/or contact lenses. It is similar to the treatment group Question 19, as follows: 9. Would you recommend glasses and/or contact lenses to some-one else? ______

4.3.1 Validation of the Control Group Questionnaire The formal psychometric properties of the questionnaire were assessed in exactly the same way as the treatment group questionnaire, and by using the statistical package for the social sciences (SPSS).

Reliability As with the treatment group, internal consistency reliability analysis was also used for the control group questionnaire, and for the same reason that the questions in the survey were designed in such way that the scales were not the same, in fact they were in 4-, 5- and 10-point Likert scale formats. Therefore, it was more appropriate to calculate reliability using “Z scores” and the result is interpreted as the same way as the Cronbach’s alpha ( ά). 150

All 19 closed-ended questions in the questionnaire were selected for internal consistency reliability analysis with 47 control study subjects. The results showed that Questions 6 and 8 had the lowest corrected item-total correlation. The Cronbach’s alpha for the overall scale was equal to 0.68. With these items removed and recalculating the reliability coefficient, the final Cronbach’s alpha was 0.70 (for exact analysis see Appendix IV).

Test-retest reliability was not done with the control group data for the same reason as for the treatment group, was previously explained in this chapter.

127 Validity Validity was as previously explained in this chapter for the treatment group.

128

C H A P T E R 5

Methods Chapter 5

5.0 Methods The study was based on two groups. 1. The treatment group – evaluates the effect, success and patient satisfaction of having the LASIK procedure. 2. The control group – evaluates the effect, success and patient satisfaction of using glasses and/or contact lenses. It controls for (a) any impact on measures of satisfaction caused by the measuring process itself and (b) natural changes over time in satisfaction with vision.

5.1 The Treatment Group Subjects Two hundred and sixteen subjects were incidentally sampled from patients who underwent simultaneous bilateral LASIK using the Chiron Technolas 217C plano-scan excimer laser with the Chiron ACS (Automated Corneal Shaper) and the Hansatome microkeratome. The subjects were recruited from within one centre (Sydney) from August 1998, and followed up to April 2002. This centre was similar to other specialty centres, it accepts patients similar to those who attending many across Australia. The procedures were performed by any one of three surgeons. Of the 216 subjects, 99 were male and 117 female. Their ages ranged from 20 to 72 years, the mean and mode being 42 years of age. The majority of the subjects were in the presbyopic age group (see Appendix V for age distribution graph).

5.2 The Control Group Subjects Since patients coming to a laser refractive centre are interested in having LASIK, recruiting non-LASIK subjects from the same centre for the control group was not possible. As there is no real waiting list system with LASIK, using a waiting list to generate a control group was also not feasible. An optometrist in Sydney was approached, but was unable to assist. Therefore an optometrist in the city of Canberra was approached and agreed to assist. An assumption of the thesis is that eyes in Canberra are equivalent to eyes in Sydney. One hundred subjects were incidentally sampled from this optometrist’s practice from April 2001 to August 2002. For the reason that half of the subjects did not respond to the second survey,

129 the study was based on only 49 subjects, of whom 25 were male and 24 female. Their ages ranged from 19 to 67 years, the mean and mode being 48 and 54 years of age respectively. This is consistent with the treatment group in that the majority of the subjects were in the presbyopic age group (see Appendix VI for age distribution graph).

5.3 Subject Criteria for the Treatment Group The inclusion criteria stipulated that subjects be suitable LASIK patients who had undergone the LASIK procedure. This study was based on 72.2% myopic subjects (with pre-operative spherical error ranging from -0.58 to -14.30 diopters, minus cylindrical error range from -0.25 to -6.25 diopters), 24.5% hyperopic subjects (with pre-operative spherical error ranging from +0.15 to +6.60 diopters, plus cylindrical error range from +0.25 to +4.75 diopters). The remaining 3.3% of the subjects were mixed astigmatic. Of the subjects, 82% had emmetropic correction and 18.3% had monovision correction (a partial correction is performed on the non- dominant eye to achieve an intended residual refractive error, range from 0.5 to 2.75 diopters, to aid reading or close work post-operatively). Prior to surgery monovision subjects had monovision demonstrated by trial frame and/or contact lens trial. Only one subject had unilateral emmetropic correction, due to a history of iritis in the fellow eye. The left eye was more frequently defined as the non-dominant eye, as there were 10% more left eyes were corrected for near vision than right eyes in the event of monovision correction. Among the subjects, 20% required at least one enhancement to one of the eyes. 9.1% of these were myopic (range from -0.10 to -2.00 diopter), 4.4% were hyperopic (range from +0.20 to +2.86), 2.3% and 3.7% were astigmatic and mixed astigmatic respectively (minus cylinder range from -0.25 to -2.50 diopters, and plus cylinder range from +0.25 to +2.50 diopters).

5.4 Subject Criteria for the Control Group The inclusion criteria stipulated that subjects must wear glasses and/or contact lenses and have similar refractive error profiles to the patients in the treatment group. The subjects were free from previous ocular injury, surgery (especially refractive surgery), or ocular pathological condition. Of the control group subjects, 87% wore glasses, 4.5 % wore contact lenses and 8.5% wore both glasses and contact lenses. There were 64.3% myopic subjects (with spherical error ranging from -0.25 to -7.50 diopters, minus cylindrical error range from -0.25 to -6.50

130 diopters), 32.7% hyperopic subjects (with spherical error range from +0.25 to +5.50 diopters). The remaining 3.1% of the subjects were astigmatic. Because the optometrist does not refract in plus cylinder, therefore, there was no plus cylinder error. Among the control subjects, 33% wore emmetropic correction without the near add prescription, and 67.3% had a near add prescription for near vision ranging from 0.75 to 2.25 diopters.

5.5 Procedures for the Treatment Group When patients returned for the post-operative assessment, they were approached by the investigator, given an information sheet outlining the aims of the project (see Appendix VII), and a consent form (see Appendix VIIIa and VIIIb) was presented to sign in the event of agreement to participate. The assessment consisted of two parts, an objective/clinical evaluation and a subjective/patient satisfaction evaluation. A. Objective/Clinical Evaluation Pre- and post-operative clinical data were extracted from the subject’s files with the permission of the surgeons and the subjects. The clinical data consisted of: 1. uncorrected visual acuity (UCVA) 2. best-corrected visual acuity (BCVA) 3. subjective refraction 4. record of pre-operative glasses and/or contact lenses prescription 5. ocular motility assessment 6. corneal topography with EyeSys and Orbscan 7. slit lamp examination 8. surgical details 9. record of any pre-existing eye disease/conditions and previous surgery or injury that might prevent the subjects from achieving their desired visual outcome post- operatively.

B. Subjective/Patient Satisfaction Evaluation This was assessed by subjects completing a survey questionnaire (see Appendix I). The survey was administered at 3 months, 6 months, 12 months and 24 months post-operatively. These time intervals were chosen in accordance with the routine clinical follow-ups. If subjects

131 required an enhancement (further treatment) to one or both eyes, administration of the survey was delayed for 3 months following the enhancement procedure to allow clinical outcomes to stabilize. For this reason, the time-line for subjects requiring enhancement was displaced compared to subjects not requiring enhancement. The differences could vary from 3 months to 24 months, depending on when the enhancement procedure was performed. The study was designed as a repeated-measures study, the questionnaire being administered at the set time intervals to monitor and detect any subtle changes over time.

Subjects could either complete the patient satisfaction questionnaire at the clinic or take it home, but were encouraged to complete the survey while they were at the clinic as recommended in the literature. 106 For subjects who completed their survey at the clinic, it was done immediately after they finished their clinical review with the surgeon. This measure avoided social-psychological artefacts, that is, subjects wanting to please their surgeon by declaring themselves satisfied, for fear of unfavourable treatment in the future 68,73-75 . Subjects who completed the questionnaire on-site were situated in a quiet, comfortable room by themselves, and encouraged to take their time to answer the questions as truthfully as possible. This ensured a quiet ambience to minimize anxiety, and solitude preventing influence by other(s) on responses to the questionnaire, thus avoiding inflation or deflation of patient satisfaction scores. 152 For subjects who chose to take the questionnaire home with them, a covering letter (see Appendix IX) was attached to the questionnaire with a prepaid postage return envelope. Subjects were urged to complete and return the questionnaire as soon as possible.

5.6 Procedures for the Control Group When subjects visited the recruiting optometrist for their initial or review consultation, they were approached randomly by the optometrist. An information sheet (see Appendix X) outlining the aims of the project was provided, and a consent form (see Appendix XIa and XIb) was presented to sign in the event of participation.

After the subjects finished their consultation with the optometrist, a questionnaire was given to them to complete. This survey 1 was equivalent to the pre-operative assessment of the

132 treatment group. Regardless of whether the subjects were at their initial or review consultation, the follow-up survey was administered 3 months later (survey 2), which was equivalent to the 3 months post-operative assessment of the treatment group. Unfortunately, as with the treatment group, there were delays as some subjects required more than one reminder for them to eventually respond. Some never responded; in fact, more than 50% of the subjects from the first survey failed to respond to the second survey. In order to retain the proposed sample size, additional new subjects were recruited using the same procedure. For the reason that the control group subjects did not have any surgical alterations, except some of them had new glasses and/or contact lenses prescribed at the end of survey 1 as part of their annual refraction up-date. It was unnecessary to have more than one follow-up, and they received only surveys 1 and 2. The assessment consisted of two parts, an objective/clinical evaluation and a subjective/patient satisfaction evaluation.

A. Objective/Clinical Evaluation The clinical data were extracted from the subjects’ files with the permission of the optometrist and the subjects. The clinical data consisted of: 1. UCVA 2. BCVA 3. record of glasses and/or contact lens prescription at survey 1 4. if new glasses and/or contact lens were prescribed at the end of survey 1, record of the new prescription 5. ocular motility assessment 6. slit lamp examination 7. record of any pre-existing eye disease/conditions and previous eye surgery or injury to the eyes.

B. Subjective/Patient Satisfaction Evaluation This was assessed by subjects completing a survey questionnaire (see Appendix III) at survey 1 at the recruiting optometrist’s practice. Subjects were informed by the optometrist that the study investigator would contact them in 3 months to conduct a phone survey as a follow up (survey 2). During the phone survey the same questionnaire and the additional questions about

133 the subjects’ glasses and/or contact lenses (see Appendix XII) were completed. These time intervals were chosen in accordance with the clinical follow-up of the treatment group. The repeated-measures were designed to monitor and detect any subtle changes over time. If a subject was not contactable, a covering letter with the additional questions (see Appendix XIII) was attached to the survey questionnaire was sent with a prepaid postage return envelope to collect survey 2 data. The subjects were urged to complete and return the questionnaire as soon as possible.

5.7 Rate of Non-responders in the Treatment Group In the literature 106 the rate of non-response is well documented, especially when a study continues over a long period of time and is in a mailed out format. Because this was a treatment outcomes study it was designed to take the form of repeated measures over 24 months assessing the clinical outcomes, patient satisfaction of the outcomes, and the changes over time. Study subjects were encouraged to return to the refractive clinic so that the post- operative assessments could be done according to the study proposal instead of by the optometrist organized by the refractive centre under the co-management protocol. Notwithstanding these measures, and a number of reminders, the non-response rate was 54% on average. To offset the non-responders, more than twice the number of subjects, 216 subjects in total, were recruited in order to retain the proposed sample size of 100 at any one survey.

5.8 Rate of Non-responders in the Control Group Similar to the treatment group, the rate of non-response in the control group was 51%, despite the fact that there were just two surveys, only 3 months apart. Having pursued all possible reminder methods, more than twice of the number of subjects was recruited in attempt to retain the proposed sample size of 100. By the end, the study only managed to maintain 49 subjects.

5.9 Methods of Reminders for the Treatment Group As stated earlier, the follow-up intervals were 3, 6, 12 and 24 months after the initial treatment or enhancement procedure. If subjects did not already have a return appointment, a reminder

134 phone call was initiated a week before the next post-operative review. If subjects were non- contactable, a reminder letter (see Appendix XIV) attached to the questionnaire was sent for the subjects to complete. If there was still no response, a phone call was made to the subject’s allocated optometrist to check and/or to obtain the clinical data. If no data were available, a second reminder phone call was made to the subject. If unsuccessful, a second reminder letter (see Appendix XV) with the questionnaire attached was sent. Having pursued all these reminder methods without success, there was no choice but to wait until the subject was due for the next follow-up, and repeat the whole process.

5.10 Methods of Reminders for the Control Group As stated earlier, the follow-up intervals were the baseline (survey 1), then 3 months thereafter (survey 2). A week prior to the follow-up, subjects were contacted by phone and a phone survey was conducted. If subjects were uncontactable, a reminder letter (see Appendix XVI) with the questionnaire attached was sent for the subject to complete. If there was still no response, the subject was phoned a second time. If unsuccessful, a second reminder letter (see Appendix XVII) with the questionnaire attached was sent. If still unsuccessful, the subject was dropped and/or a new subject was recruited.

5.11 Data Analysis for the Treatment and Control Group A. Clinical data evaluation Unit of analysis for clinical data was individual eye. The visual acuity data in this study were converted into decimal scores to include the + and – letter(s) the subjects missed or read correctly for accuracy (see Section 5.12.2 for more detail). Also, because the control group only had the baseline and 3 months follow-up, which corresponded to the pre-operative and 3 months post-operative assessment in the treatment group, clinical data comparisons between the treatment and control groups involved two surveys only: pre-operative to 3 months post- operative in the treatment group versus baseline to 3 months follow-up in the control group. For all multiple analyses, instead of using different Bonferroni Adjusted statistical significance values, due to the different number of variables involved for each analysis, a fixed statistical significance value p < 0.01 was used to balance between the possibility of committing type I and type II errors.

135 Research question 1: From an efficacy perspective, what level of uncorrected distance visual acuity can LASIK achieve? To assess this, the post-operative UCVA was analyzed using descriptive statistics to obtain frequency distributions.

Research question 2: How stable is the post-operative uncorrected distance visual acuity? To assess this, the pre-operative BCVA and post-operative UCVA at surveys 1 to 4 were analyzed using descriptive statistics to obtain frequencies of distribution. Because there were different response rates at each survey and one or more surveys had only very small sample sizes, rather than using repeated measures ANOVA, repeated measures t-tests were conducted to evaluate any significant changes over time.

Research question 3: How do subjects’ pre-operative BCVA compare to their 3 months post- operative UCVA? And how does it compare to the BCVA at baseline and 3 months in the control group? To assess this, a 2(group) x 2(time) ANOVA was conducted using the pre-operative BCVA and 3 months post-operative UCVA in the treatment group versus the BCVA at baseline and 3 months in the control group. This statistic was chosen in order to detect differences in two independent group means of visual acuity at two time intervals.

Research question 4: From a safety perspective, what level of best-corrected distance visual acuity can LASIK achieve? Safety. In refractive surgery, safety is assessed by comparing the BCVA pre- and post- operatively. Ideally the post-operative BCVA should be equal to or better than but must not be worse than the pre-operative BCVA. In order to assess this, the post-operative BCVA was analyzed using descriptive statistics to obtain frequency distributions.

Research question 5: How stable is the post-operative best-corrected distance visual acuity? In order to assess this, the pre- and post-operative BCVAs at surveys 1 to 4 were analyzed using repeated measures t-tests to evaluate any changes over time. This statistic was chosen as previously explained in research question 2 above.

136 Research question 6: How does subjects’ pre- and 3 months post-operative best-corrected distance visual acuity compare to the BCVA at baseline and 3 months in the control group? To assess this, a 2(group) x 2(time) ANOVA was conducted using the pre-operative and 3 months post-operative BCVA in the treatment group versus the BCVA at baseline and 3 months in the control group. This statistic was chosen as previously explained in research question 3 (see page 135).

Research question 7: For monovision corrected subjects, what level of uncorrected near visual acuity can LASIK achieve? For subjects who elected to have monovision correction, their post-operative uncorrected near visual acuity (UCNVA) was analyzed using descriptive statistics to obtain frequency distributions.

Research question 8: How stable is the post-operative uncorrected near visual acuity? To assess this, the post-operative UCNVAs at 3 to 24 months were analyzed using repeated measures t-tests to evaluate any significant changes over time. This statistic test was chosen as previously explained in research question 2. Unfortunately, the near visual acuity pre-LASIK for the treatment group, and at baseline and 3 months for the control group were not extracted from the subjects’ files, therefore comparison between pre- and post-operatively and between the two groups was not possible.

Research question 9: Repeated measures study is known to have different response rates in each survey. Thus, is there any significant difference in post-operative uncorrected distance, near visual acuity and best-corrected distance visual acuity between subjects who returned for more than one survey and those who returned for only one survey? There were two speculations: (1) subjects who returned for only one survey may have achieved excellent visual acuity, were very satisfied, and fewer of them returned for later surveys; and (2) subjects who returned for only one survey may have achieved less desirable visual outcomes, were dissatisfied and did not bother to return for later surveys, as suggested by literature. 106,109,119 To assess this, an independent samples t-test was conducted to compare the two groups “subjects returned for more than one survey” and “subjects returned for one

137 survey only” on their post-operative uncorrected distance, near visual acuity, and best- corrected distance visual acuity at survey 1. This statistic was chosen in order to determine whether the visual acuity scores from the two groups were from the same or different populations.

Research question 10: From an accuracy perspective, how does the intended surgical goal compare to that achieved? To assess this, the subjects’ surgical results went through the process of computer codification, and descriptive statistics were used to analyze the frequency of categories.

Research question 11: What are the ranges of residual refractive errors? How stable are they? Subjects electing to have monovision correction were excluded from this analysis, because their residual refractive errors were intentional. Therefore, the following analyses include only the subjects who had emmetropic correction (intended for zero refractive error post- operatively), to illustrate the accuracy of the procedure. For post-operative residual errors, myopic and hyperopic sphere, minus and plus cylinder at all four surveys were analyzed separately using descriptive statistics to obtain frequency distributions. Under- and over- corrections were illustrated by bar graphs, then repeated measures t-tests were performed to evaluate any significant changes over time. This statistic was chosen as previously explained in research question 2 (see page 135).

Research question 12: Repeated measures study is known to have different response rates in each survey. Thus, is there any significant difference in residual refractive errors between subjects who returned for more than one survey and those who returned for only one survey? There were two speculations, similar to those mentioned earlier for research question 9: (1) patients who returned for only one survey achieved minimal to no residual refractive error, were very satisfied, and fewer of them returned for later surveys; and (2) patients who returned for only one survey may have achieved less desirable clinical outcomes, were dissatisfied and did not bother to return for later surveys. To assess this aspect, an independent samples t-test

138 was conducted to compare the two groups “patients returning for more than one survey” and “patients returning for only one survey” on their post-operative residual refractive errors (myopic and hyperopic sphere, minus and plus cylinder errors were analyzed separately) at survey 1. This statistic was chosen in order to determine whether the residual refractive errors scores from the two groups were from the same or different populations.

B. Subjective or patient satisfaction questionnaire evaluation The subjective or patient satisfaction questionnaire contained 20 questions in the treatment group and 9 questions in the control group (see Appendices I and III). Internal consistency reliability for each scale was assessed by Cronbach’s alpha ( α) (see Chapter 4, page 122 and 127, and Appendices II and IV).

The open-ended questions in the treatment and control group questionnaires were initially computer codified, then content analysis was performed and frequency of categories was analyzed using descriptive statistics. The closed-ended questions in the treatment and control group questionnaires were scaled according to the Likert scale, were also computer codified, and then descriptive statistics were performed to obtain frequency distributions. As has been mentioned, this is a treatment outcome investigation and the patient satisfaction survey was administered from 3 months post-operatively, thus the subjective or patient satisfaction questionnaire data comparisons between the treatment and control groups involved only two surveys: 3 months to 6 months post-operative in the treatment group versus baseline and 3 months follow-up in the control group. For all multiple analyses, instead of using different Bonferroni Adjusted statistical significant values due to the different number of variables involved for each analysis, a fixed statistical significant value p < 0.01 was used to balance between the possibility of committing type I and type II error.

Research question 13: How did the subjects learn about LASIK, why and what did they want to achieve from having LASIK? The first section of the questionnaire consisted of five questions which were unique to the treatment group, to establish subjects’ characteristic profiles and their goals of having LASIK. They were:

139 1. How did the subject first learn about the LASIK procedure? 2. Who referred the subject? 3. What was the subject’s PRIME objective for having the surgery? 4. What were the subject’s other reason(s) for having the surgery? 5. What was the subject’s PRIME desired end result? For these open-ended questions, content analysis was performed, and responses were reviewed. Key themes were identified, and then compared to the responses. Frequencies were recorded for each theme.

Research question 14*: For questions that are comparable between the treatment and control group, how do subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, overall quality of life, treatment outcome and satisfaction of treatment) compare between the two groups? As stated earlier, because the control group had only the baseline and 3 months follow-up, which corresponded to the pre-operative and 3 months post-operative assessment in the treatment group, all comparisons between the treatment and control group involved surveys 1 and 2 only. The second section of the treatment group questionnaire consisted of four questions which were designed to be comparable between the treatment and control group. These questions were: Question 6a-d for the treatment group compared with Question 2a-d for the control group, which assessed ocular symptoms. In the control group there were subjects who wore glasses and others who wore contact lenses, but only four subjects who wore contact lenses responded to both surveys 1 and 2, a number which is too small to have any meaningful analysis or comparison by itself. Therefore, the comparison analysis was performed using the treatment group and the control group consisting of both glasses and contact lens wearing subjects. Descriptive statistics were performed to obtain frequency distributions for the individual group, then a 2(group) x 2(time) ANOVA was conducted. This statistic was chosen to detect differences in two independent group means of ocular symptoms at two time intervals.

140 Question 7a-d for the treatment group compared with Question 4a-d for the control group. These questions assessed the subjects’ rating of their visual abilities such as distance and near vision, day and night driving. Despite the skewness of scores in these questions, between groups ANOVA is robust against assumption violation. Repeated measures ANOVA is less robust, because non-normal repeated measures distributions often do not have homogeneous co-variances. This problem arises only when there are more than two occasions of measurement, so it does not affect a 2(group) x 2(time) ANOVA. 154 Thus, descriptive statistics were performed to obtain frequency distributions. A 2(group) x 2(time) ANOVA was conducted to compare groups across time. This statistic test was chosen to detect differences in two independent group means of subjects’ rating at two time intervals. Question 8a-d for the treatment group compared with Question 5a-d for the control group. These questions assessed the subjects’ rating of their visual improvement in performing physical, social/recreational, home and home activities. Descriptive statistics were performed to obtain frequency distributions, then 2(group) x 2(time) ANOVA was conducted as explained above.

Question 9 was an open-ended question determining whether subjects still needed to wear glasses and/or contact lenses post-operatively, and it was only relevant to the treatment group. Content analysis was performed and frequency of categories was analyzed using descriptive statistics.

Question 10 for the treatment group compared with Question 3 for the control group. These were open-ended questions which identifies the subjects’ MAIN symptoms experienced post- operatively. Content analysis was performed and frequency of categories was analyzed using descriptive statistics.

Question 11 for the treatment group compared with Question 6 for the control group. These questions assessed the subjects’ overall quality of life. Descriptive statistics were performed to obtain frequency distributions, then 2(group) x 2(time) ANOVA was conducted as previously explained for Question 7a-d above.

141 The third and fourth section (part I) of the questionnaire consisted of seven questions: four questions to assess the amount of information given to the subjects before, during and after the surgery, and whether the subjects fully understood the information; and three questions to assess subjects’ rating of the surgery success, and whether the surgery outcomes met their pre-operative expectations. All the questions were relevant to the treatment group only. These were closed-ended questions, and descriptive statistics were performed to obtain frequency distributions. They were: 12. Was enough information given to you about LASIK prior to surgery? 13. Was enough information given to you about what to expect immediately after the surgery regarding pain, glare and blurriness? 14. How much information were you given regarding the regime of using eye drops and medications? 15. How would you rate the success of the surgery? 16. How do you compare your satisfaction now with your pre-operative expectations? 17. Now that you have undergone the surgery, knowing what you know now, would you still have the surgery? 18. Would you have the second eye done if required?

The fourth section (part II) of the questionnaire consisted of two questions designed to be comparable between the treatment and control group with a few minor differences in wording to assess whether the subjects would recommend the treatment and how satisfied they were. Research question 15*: From the treatment satisfaction perspective, would subjects recommend one form of treatment over the other when comparing between the treatment and control groups? As this is an open-ended question, content analysis was performed and frequencies of categories were recoded into “recommend” and “not recommend” groups for comparison. With the data being categorical, “treatment group” versus “control group”, “recommend” versus “not recommend”, because too many subjects were in the one category, namely the “treatment” group, rather than using a rank order test which may causes category to collapse, cross-tab 2X2 factorial analysis was conducted.

142 Research question 16*: Again, from treatment satisfaction perspective, how do the satisfied and dissatisfied subjects compare between the treatment and control groups? Question 20 in the treatment group and Question 7 in the control group assessed how satisfied the subjects were with their treatment. As these were closed-ended questions and the responses were subjects’ satisfaction scores, descriptive statistics were performed to obtain frequency distributions. In view of the fact the subjects’ satisfaction scores were skewed toward “satisfied”, for comparison purposes the scores were recoded, such that subjects who were “much more satisfied” and “somewhat more satisfied” became the “satisfied” group. Subjects who were “about the same”, “undecided”, “somewhat less satisfied” and “less satisfied” became the “dissatisfied” group. This made up (average of four surveys) 77% “satisfied” and 23% “dissatisfied” subjects, a ratio of almost 4:1. Likewise the subjects’ satisfaction scores for Question 7 in the control group were recoded for comparison purposes. With the data being categorical, “satisfied” versus “dissatisfied” and “treatment group” versus “control group”, cross-tab 2 x 2 factorial analysis for relatedness was conducted as previously explained in research question 15 (see page 141).

Research question 17*: From a stability perspective, are there any significant changes in subjects’ responses to the questionnaire regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction over time? In a repeated measures patient satisfaction study it is essential to identify any significant changes in subjects’ responses over time in order to identify sources of satisfaction or dissatisfaction. To assess this, all the closed-ended questions (6, 7, 8, 11, 12, 13, 14, 15, 16 & 20) in the questionnaire were included for repeated measures paired-samples t-test analysis. This statistic was chosen as t-tests like ANOVA are robust against violation of the assumption of normal distributions for sample sizes greater than 30, and the analysis does not include co- variances, so it is appropriate for determining whether the difference between means for the two sets of scores is the same or different.

Research question 18: Repeated measures study is known to have different response rates at each survey. Thus, is there any significant difference in the subjects’ responses to the

143 questionnaire between subjects who returned for more than one survey and those who returned for only one survey? It was speculated that subjects who returned for only one survey might be less satisfied, as suggested by literature. 106,109,119 To assess this aspect, an independent samples t-test was conducted using the recoded responses of two groups: “patients returned more for than one survey” and “patients returned for only one survey” and their responses to all the closed-ended questions at survey 1 (Questions 6, 7, 8, 11, 12, 13, 14, 15, 16 & 20, a total of 19 variables). This statistic was chosen to determine whether the scores from the questionnaires of the two groups were from the same or different populations.

C. Establish relationship between clinical and subjective/patient satisfaction variables for the treatment group Research question 19*: Is there any correlation between the uncorrected distance and near visual acuity achieved post-operatively and subjects’ satisfaction? To assess this, bivariate Spearman’s rank-order correlation was conducted using post- operative uncorrected distance and near visual acuity, each analyzed separately with subjects’ satisfaction scores (scores in Question 20) in all four surveys. Rather than bivariate Pearson product-moment correlation, this statistic was chosen due to the violation of normal distributions. Unlike ANOVA, Pearson correlations are not robust against assumption violations.

Research question 20*: Is there any correlation between the change from pre-operative best-corrected to post-operative uncorrected distance visual acuity and subjects’ satisfaction? For subjects who had emmetropic correction, perhaps the change from pre-operative distance best-corrected to post-operative uncorrected visual acuity might better illustrate the visual improvement of having the procedure, and thus might affect subjects’ satisfaction. To assess this, bivariate Spearman’s rank-order correlation was conducted using the change from pre- operative BCVA to post-operative UCVA and subjects’ satisfaction scores (scores in Question 20) in all four surveys. This statistic was chosen as previously explained for research question 19 above.

144 Research question 21*: Is there any correlation between the change from pre- to post- operative uncorrected distance visual acuity and subjects’ satisfaction? Again, for emmetropic corrected subjects, perhaps the change from pre- to post-operative uncorrected distance visual acuity might better illustrate the visual improvement of having the procedure, which may affect the subjects’ satisfaction. To assess this, bivariate Spearman’s rank-order correlation was conducted using the change pre- to post-operative uncorrected distance visual acuity and subjects’ satisfaction scores (scores in Question 20) in all four surveys. This statistic was chosen as previously explained for research question 19 (see page 143).

Research question 22*: Is there any correlation between post-operative residual refractive errors and subjects’ satisfaction? If the aim of LASIK is to reduce or eliminate refractive error, any post-operative residual refractive error, especially greater than one diopter in either spherical or cylindrical error or both, might be considered a less desirable surgical outcome, and thus subjects might be less satisfied. To assess this, bivariate Spearman’s rank-order correlation was conducted using post-operative residual refractive errors and subjects’ satisfaction scores (scores in Question 20) in all four surveys. Myopic, hyperopic sphere, minus and plus cylindrical errors were analyzed separately. Only emmetropic corrected subjects were included for this analysis as the residual refractive errors for the monovision corrected subjects were intentional. This statistic was chosen as previously explained for research question 19 (see page 143).

Research question 23*: Is there any correlation between post-operative uncorrected binocular visual acuity achieved and subjects’ responses to the questionnaire regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment? Although this study consisted of majority of subjects who had bilateral emmetropic correction, but some had monovision correction and/or unilateral correction to achieved monovision correction. However, when the subjects performed their daily tasks they used binocular vision. If subjects achieved better overall uncorrected visual acuity, would they give higher rating in the satisfaction questionnaire? In order to assess this, bivariate Spearman’s rank-order

145 correlation was conducted using post-operative uncorrected binocular visual acuity, with subjects’ responses to the questionnaire at all four surveys. All the closed-ended questions (Questions 6a-d, 7a-d, 8a-d, 11, 12, 13, 14, 15, 16, and 20, a total of 19 variables) were included for analysis. This statistic test was chosen as previously explained for research question 19 (see page 143).

Research question 24*: Is there any significant difference in subjects’ responses to the questionnaire between subjects who were satisfied and those who were dissatisfied? If subjects were satisfied would they give higher ratings in the questionnaire? To identify the associations, t-test analysis was conducted using the recoded subjects’ satisfaction scores to question 20 (the “satisfied” and “dissatisfied” subjects, as described earlier for research question 16, page 142) and the subjects’ responses to the questionnaire at all four surveys. All the closed-ended questions, (Questions 6a-d, 7a-d, 8a-d, 11, 12, 13, 14, 15, and 16, a total of 18 variables) were included for analysis. This statistic was chosen in order to determine whether the scores from the questionnaires from the two groups were from the same or different populations.

Research question 25: Is there any significant difference in subjects’ responses to the questionnaire between those who no longer required and those who still required glasses and/or contact lenses post-operatively? If the aim of having the LASIK procedure was to be independent of glasses and/or contact lenses, it was speculated that subjects who still required glasses and/or contact lenses post- operatively would respond to the questionnaire negatively. To assess this aspect, Question 9 identified subjects who still required to wear glasses and/or contact lenses post-operatively. The responses of categories were recoded into “glasses” and “no glasses” groups, which made up (average of four surveys) 74% “no glasses” and 26% “glasses”, almost a 4:1 ratio. A t-test analysis was conducted with the subjects’ responses to the questionnaire at all four surveys. All the closed-ended questions (Questions 6a-d, 7a-d, 8a-d, 11, 12, 13, 14, 15, 16, and 20, a total of 19 variables) were included for analysis. This statistic was chosen as previously explained for research question 24 above.

146 The literature 58-60,63-65,126 documents significant difference in satisfaction between males and females. Thus a question addressed this issue. Research question 26: Is there any significant difference in satisfaction between male and female subjects? To investigate this, the coding of “male” and “female” subjects, which was in a 99:117 ratio, and the recoded subjects’ satisfaction scores to Question 20 (the “satisfied” and “dissatisfied” subjects as described for research question 16, page 142) in the questionnaire at all four surveys, were used to create 2 x 2 categorical variables. For the reason that too many subjects were in the one category, namely the “satisfied” group, rather than using a rank order test which can cause categories to collapsed, a Chi-Square test for relatedness was conducted.

As above, the literature 58-60,63-65,126 documents significant differences in satisfaction between younger and older patients. Thus a question addressed this issue. Research question 27: Is there any significant difference in satisfaction between subjects who are younger than and those who are older than 40 years of age? To investigate this, the subjects’ ages were recoded such that subjects who were less than 40 years of age were recoded as “younger than 40 years old”, and those who were 40 or older were recoded as “older than 40 years old”, which made up 40% and 60% respectively. The recoded subjects’ satisfaction scores to question 20 (the “satisfied” and “dissatisfied” subjects as described for research question 16, page 142) in the questionnaire at all four surveys were used to create a 2 x 2 categorical variables. A Chi-Square test for relatedness was conducted as previously explained for research question 26, page 145.

Research question 28: Is there any significant difference in subjects’ responses to the questionnaire between subjects who are younger than and those who are older than 40 years of age? The literature 58-60 suggested that older patients tend to be more satisfied with health care than younger patients. To investigate this, an independent samples t-test was conducted using the recoded subjects’ ages, “younger than 40 years of age” and “older than 40 years of age” (as described for research question 27 above) and the subjects’ responses to the questionnaire at all four surveys. All the closed-ended questions (Questions 6a-d, 7a-d, 8a-d, 11, 12, 13, 14, 15, 16, and 20, a total of 19 variables) were included for analysis. This statistic was chosen in

147 order to determine whether the scores from the questionnaires of the two groups are from the same or different populations.

Research question 29: Is there any significant difference in satisfaction between myopic and hyperopic subjects? It has been illustrated that hyperopic correction may not be as effective as myopic correction, which led to the speculation that hyperopic subjects may be less satisfied then myopic subjects. To assess this aspect, the coding of two groups: “myopic” and “hyperopic” subjects and the recoded subjects’ satisfaction scores to Question 20 (the “satisfied” and “dissatisfied” subjects as described for research question 16, page 142) in the questionnaires at all four surveys were used to create a 2 x 2 categorical variables. Chi-Square test for relatedness was conducted as previously explained for research question 26, page 145-146.

Research question 30: Is there any significant difference in post-operative uncorrected distance and near visual acuity achieved between myopic and hyperopic subjects? It has been illustrated that hyperopic subjects were more satisfied than myopic subjects. This led to the speculation that hyperopic subjects were more satisfied because they achieved better unaided distance and/or near visual acuity than the myopic subjects. To assess this aspect, the coding of two groups: “myopic” and “hyperopic” subjects and the post-operative uncorrected distance and near visual acuity at all four surveys were analyzed separately. Because of the different response rates at each survey, and the fact that one or more surveys had only very small sample size, rather than using repeated measures ANOVA, independent samples t-tests were conducted. For post-operative uncorrected distance visual acuity, the analysis includes emmetropic corrected subjects only. For post-operative uncorrected near visual acuity, the analysis includes only monovision corrected subjects as they were the only ones having near visual acuity data. This statistic was chosen to detect differences in group means between the two independent groups.

Research question 31: Is there any significant difference in subjects’ rating of their uncorrected distance and near visual acuity (Questions 7a & b in the questionnaire) between myopic and hyperopic subjects?

148 It is possible that hyperopic subjects were more satisfied because subjectively, they perceived and rated their unaided distance and/or near visual acuity (Questions 7a & b in the questionnaire) higher than the myopic subjects. To assess this aspect, the coding of two groups: “myopic” and “hyperopic” subjects and their ratings in Questions 7a and b in the questionnaire at all four surveys, each analyzed separately, were used to conduct an independent samples t-test analysis, as previously explained for research question 30, page 147.

Research question 32: Is there any significant difference in subjects’ responses to the rest of the questionnaire between myopic and hyperopic subjects? If hyperopic subjects were more satisfied, perhaps their rating responses in the rest of the questionnaire were better than those of the myopic subjects. To assess this aspect, independent samples t-tests were conducted with the coding of two groups: “myopic” and “hyperopic” subjects and their ratings for the remaining closed-ended questions (Questions 6a-d, 7c-d, 8a- d, 11, 12, 13, 14, 15, 16, and 20, a total of 17 variables) in the questionnaire at all four surveys. This statistic was chosen as previously explained for research question 30, page 147.

Research question 33: Is there any significant difference in satisfaction between subjects who had mild and those who had severe refractive errors pre-operatively? It was speculated that patients with severe refractive errors pre-operatively had more impaired unaided vision, and thus would notice more visual improvement post-operatively and perhaps be more satisfied than those with milder refractive errors. To assess this, myopic, hyperopic sphere, minus and plus cylindrical errors were each analyzed separately. The recoded responses of two groups: “less than” and “more than 4D” myopic sphere then cylindrical errors, likewise “less than” and “more than 3D” hyperopic sphere then cylindrical errors with the recoded subjects’ satisfaction scores to Question 20 (the “satisfied” and “dissatisfied” subjects as described for research question 16, page 142) in the questionnaire at all four surveys were used to create 2 x 2 categorical variables. Chi-Square tests for relatedness were conducted as previously explained for research question 26, page 145-146.

149 Research question 34: Is there any significant difference in satisfaction between emmetropic and monovision treated subjects? It was revealed in the questionnaire analysis that there were subjects who could not adapt to monovision post-operatively, and responded negatively throughout the questionnaire. Perhaps dissatisfaction may correlate with monovision treated patients. To assess this aspect, the coding of two groups: “emmetropic” and “monovision” treated subjects and the recoded subjects’ satisfaction scores to Question 20 (the “satisfied” and “dissatisfied” subjects as described for research question 16, page 142) in the questionnaire at all four surveys were used to create 2 x 2 categorical variables. A Chi-Square test for relatedness was conducted as previously explained for research question 26, page 145-146.

Research question 35: Is there any significant difference in satisfaction between subjects who did not and those who required an enhancement? If the aim of LASIK was to reduce or eliminate refractive errors, but the surgical result did not achieve the intended target and the subjects required enhancement(s), would the subjects be less satisfied? To assess this aspect, the coding of two groups: “enhancement” and “no enhancement required” and the recoded subjects’ satisfaction scores to Question 20 (the “satisfied” and “dissatisfied” subjects as described for research question 16, page 142) in the questionnaire at all four surveys were used to create a 2 x 2 categorical variables. A Chi- Square test for relatedness was conducted as previously explained for research question 26, page 145-146.

Research question 36*: Are there variables in the study that can be used as predictors to explain patient satisfaction? According to the literature, 143 “at a minimum, the survey should demonstrate the multiple R- square from a regression model” (p. 23). The regression equation is used to identify variables which can be predictors or variances that explain patient satisfaction. To satisfy this requirement, a logistic regression was conducted, as standard multiple regression is affected by non-normal distributions. To overcome this problem, satisfaction was recoded into a dichotomy, as explained for research question 16, page 142. Logistic regression makes few assumptions about the shape of distributions.

150 5.12 Problems Encountered in the Study In the exploratory interviews and literature,145 patients have stated that they preferred to have their follow-ups done by the consultant ophthalmologist/surgeon. Refractive clinics in Australia, as well as around the world, continue to have their patients’ post-operative care done by nominated or affiliated optometrists. This is usually referred to as “optometrist co- management.” Some patients are suited for this co-management arrangement because they live far from the refractive clinic, but according to Mannis et al. 142 (p. 828), This so-called co-management is a controversial issue, which has been of concern to the ophthalmology community at large. Proponents of co-management suggest that this arrangement is for the convenience of the patient and is more cost- effective and efficient, and hence, in the patient’s best interests. Opponents of co- management, on the other hand, view this practice as a thinly veiled marriage of convenience in which the optometrist refers patients for surgery and receives compensation for participation in the postoperative care. It is difficult to support the supposition that a practice in which ceding postoperative care to non- physicians enhances quality of care. The American Academy of Ophthalmology and the American Society of Cataract and Refractive Surgery have issued a joint statement recommending that this practice be limited to situations in which there is limited access to regular ophthalmological care.

The co-management arrangement was not only a controversial issue, but also created difficulty in data collection for this study and caused deviation from the study protocol. Specifically, the patients’ pre-operative visual acuity assessed using a particular visual acuity chart, but post- operatively patients were sent to the optometrists under the co-management scheme, where patients’ post-operative uncorrected, corrected visual acuity and refraction were assessed by multiple optometrists using number of different visual acuity charts. Following the study procedure for the treatment group, this information extracted from the subjects’ files formed the majority of the study post-operative data. This imposed a number of problems: different lines of visual acuity in different charts used, different number of letters in lines in different charts used, different testing conditions and different examiners. Instead of the subjects completing the patient satisfaction questionnaire on-site, it became a mailed-out survey for

151 those who had their post-operative follow-ups by optometrists. Also, the time frame of collecting the clinical and patient satisfaction data was either delayed or mistimed, and sometimes was impossible. 5.12.1 Optometric Co-management Caused Deviation in Clinical Data Collection Despite the fact the permission was given by the refractive clinic to have the study subjects return to the clinic for their follow-ups instead of having optometric co-management, this permission was not implemented within the clinic’s administration. Therefore, it was extremely difficult to reinforce the study’s procedure against the clinic’s procedural protocol. Thus, majority of the post-operative clinical data in this study were collected by the optometric co-management structured by the refractive clinic.

Clinical data such as uncorrected and corrected visual acuity and subject refraction can be affected by the type of visual acuity chart used, the contrast, the number of lines and letters and how they are displayed on the charts. Also, multiple examiners and testing conditions can affect the data. More specifically, the pre-operative BCVA was meticulously refracted by the surgeon to achieve visual acuity as high as 6/3 during the consultation prior to surgery, whereas post-operatively the co-management optometrists used different visual acuity charts where some of the charts might not have visual acuity beyond 6/6, or some optometrists might not have refracted beyond 6/6, and therefore subjects with better than 6/6 might not have been captured. For the interests of this study, discussion here focuses on the significant effect of different visual acuity charts used via co-management.

To understand the significance of this issue, one must understand that commonly used visual acuity charts have many different combinations of lines on the charts, and that each chart has a different number of letters on each line, and the visual acuity as a measurement therefore has a different meaning according to the chart that was used. Figure 5-1 shows just a small variety.

152 6/60 6/60 6/60 6/60

6/30 6/36 6/36 6/36 6/21

6/24 6/15 6/24 6/24 6/12 6/18 6/18 6/18 6/9 6/7.5 6/12 6/12 6/12 6/6 6/9 6/9 6/9 6/4.5 6/6 6/7.5 6/3.9 6/5 6/6 6/6 6/3 6/4 6/5 Chart 1 Chart 2 Chart 3 Chart 4 Fig. 5-1. Variety of visual acuity charts commercially available.

Each visual acuity chart is useful for determining an individual’s level of visual acuity, but there are shortcomings when one tries to quantify visual acuity as a score, especially to quantify changes over a period of time. Because different visual acuity charts exist and standards of measuring visual acuity vary, Figure 5-2 is a table of equivalence compiled by Ferris et al.155 to interpret the visual acuity measurement used world-wide since 1982.

Fig. 5-2. Different units of visual acuity measurement.155

As commercially available visual acuity charts changed, so did the “table of equivalence” as shown in Figure 5-3. This table was compiled by J. T. Holladay, 156 and first appeared in the February 2004 issue of the Journal of Cataract and Refractive Surgery .

153

Fig. 5-3. More recent units of visual acuity measurement.156 The table has become much more complicated within 22 years. Additional lines have been added, and the increment between each line has become smaller than in the table in Figure 5-2. This has significant effects in quantifying visual acuity.

In common practice, visual acuity is recorded as the smallest line read by each eye, but one or two mistakes per line are often allowed. In clinical research, this type of recording has some important limitations, because the number of mistakes and/or the additional letters read correctly cannot be quantified. This reduces the accuracy of the measurement. For example, to have a visual acuity of 6/6 with chart 2 in Figure 5-1 one must correctly identify seven out of eight letters (89%) on that line, but a visual acuity of 6/36 requires the identification of only one out of two letters (50%). Also, the most commonly used visual acuity charts do not have a regular progression from one line to the next, so lines lost or gained from one visit to the next cannot be calculated. For example, with chart 2 in Figure 5-1, a two-line loss from 6/21 to 6/60 is almost a tripling of the visual angle, but the two-line loss from 6/6 to 6/9 is less than a doubling of the visual angle.

154 Ferris et al.155 introduced the notation +1 or -2 to specify visual acuity, to make recording more accurate. Furthermore, to calculate the + or – letter(s), Ferris et al. suggested using charts with the same number of letters and having a regular progression, such as shown in Figure 5-4.

Chart 1 to test the right eye Chart 1 to test the left eye Fig. 5-4. New visual acuity charts by Ferris et al. 155

According to Ferris et al.,155 such charts will simplify calculation and will standardize and monitor the change in visual acuity to one letter accuracy. These new visual acuity charts are intended to resolve a number of problems inherent in currently used charts, including differences in the spacing and size of the letters, letters and line difficulties, the physical characteristics of the chart such as the material surface, illumination, test distance, and the need to have different charts to test different eyes to avoid memorization of the letters. Unfortunately, the visual acuity charts of Ferris et al. are rarely used in optometric and ophthalmic practices

5.12.2 Quantification of Visual Acuity Scores In order to accurately quantify visual acuity, Ferris et al.155 converted the Snellen visual acuity measurement into a decimal fraction by simply dividing the numerator of the Snellen fraction by the denominator. The logarithm of the reciprocal of this decimal visual acuity approximates the logarithm of the minimal angle of resolution. The new charts of Ferris et al. have a 0.1 LogMAR unit difference between each line, and each line has five letters. An interpolated

155 LogMAR score can be created by assigning 0.02 LogMAR units (that is, 0.1 divided by 5) for each letter read correctly. For example, 6/7.5 +3 = 6/.7.5 - 6/6 – (3 x 0.02) = +0.1 – 0 – (0.06) = +0.04

Therefore, 6/7.5 +3 is an interpolated LogMAR score of +0.04 as a decimal visual acuity score. This principle can be extended to any lines and letters that are read correctly. Changes in this visual acuity score over time can be easily tested. The system facilitates quantitative data analysis, which is difficult with most currently used charts. Unfortunately, the visual acuity charts of Ferris et al were not used in the refractive clinic or co-management optometric practices from which the data of this study were extracted. It was necessary to provide a method to calculate and validate visual acuity scores that incorporated all the lines and letters on the visual acuity charts used by the refractive clinic and the co-management optometric practices.

As in the principle used by Ferris et al, visual acuity in this study was converted into a decimal score which included the + and – letter(s) the subjects missed or read correctly, by modifying Dr R. Heard’s method. 2 All the pre-operative visual acuities were measured by the consultant surgeon at the refractive clinic using the visual acuity chart shown in Figure 5-5. Post- operatively, the visual acuities were measured by different co-management optometrists using different charts with different lines. In order to validate all the visual acuity data pre- and post- operatively, the visual acuity chart in Figure 5-5 was expanded as shown in Figure 5-6, with an estimation of the number of letters in each line based on the known visual acuity charts.

2 Dr R. Heard is a senior lecturer in the School of Applied Vision Sciences and School of Behavioural and Community Health Sciences at the University of Sydney. His method consists of determining the vertical height of the Snellen letters on the Snellen visual acuity chart, using trigonometry to determine the angle subtended at the eye at 6 metres.

156

Fig. 5-5 Visual acuity chart used by refractive clinic.

Figure 5-6. Visual acuity chart incorporating all the lines of visual acuity in the charts used by the refractive clinic and the optometrists. The Snellen visual acuities in this study were converted into decimal scores by dividing the numerator by the denominator. To calculate the + or – letter(s) that patients missed or read correctly, the two lines of visual acuity involved were converted into two decimal scores, the difference between the two decimal scores was calculated, and was divided by the number of letters on the line of visual acuity patient read last. This defined the value per letter of that line, which was then multiplied by the number of letter(s) the subject missed or read correctly, to produce the value of the + or – letter(s). If the subject missed a letter(s), the decimal score of the last line of visual acuity the subject read was used to subtract the value of – letter(s) missed. If the subject read an additional letter(s) on the next line, the decimal score of the last

157 line of visual acuity the subject read was used to add the value of + letter(s) read on the next line. Three illustrative examples follow.

Example 1. For a subject who achieved 6/6 -1, the calculation process was as follows: 1. The subject missed one letter, which means that the level of visual acuity dropped just below 6/6. Therefore, the lines involved are the current line and the previous line on the chart. In this case, they are the 6/6 and 6/7.5 lines. 2. Convert the two lines of visual acuity involved into two decimal scores. That is, 6/6 becomes 1 and 6/7.5 becomes 0.8. 3. Subtract one decimal score from the other to define the difference between the two lines. That is, 1-0.8 = 0.2. 4. There are five letters on the 6/6 line, therefore, 0.2 divided by 5 = 0.04. This represents the value of each letter on the 6/6 line. 5. Because the subject missed one letter on the 6/6 line, use the decimal score of 6/6 minus the value of one letter missed. That is, 1 – 0.04 = 0.96.

6. So 6/6 -1 = 0.96.

Example 2. For a subject who achieved 6/6 +2 , the calculation process was as follows: 1. The subject read two more letters on the next line, which means the level of visual acuity went just above 6/6. Therefore, the lines involved are the current line and the next line on the chart. In this case, they are the 6/6 and 6/5 lines. 2. Convert the two lines of visual acuity involved into two decimal scores. That is, 6/6 becomes 1 and 6/5 becomes 1.2. 3. Subtract one decimal score from the other to define the difference between the two lines. That is, 1.2 – 1.0 = 0.2. 4. There are five letters on the 6/5 line, therefore 0.2 divided by 5 = 0.04. This represents the value of each letter on the 6/5 line. The subject read two more letters, so multiply 0.04 by 2. 5. Using the decimal score of 6/6 add the value of two additional letters. That is, 1 + (0.04 x 2) = 1.08

6. So 6/6 +2 = 1.08.

158 Example 3. For a subject who achieved 6/6 -1+2 , the calculation process was as follows:

1. The first part of the calculation involves 6/6 -1, which has been outlined in Example 1. The second part of the calculation involves the two additional letters, thus, the calculation

process repeats steps 1 to 4 as outlined in Example 2. 2. Finally, add the two parts of the calculation together, 0.96 + 0.08 = 1.04

3. So 6/6 -1+2 = 1.04

With this method, every single letter can be accounted for. With regard to lines lost or gained in visual acuity, although the refractive surgery community uses this figure to express clinical success and the safety of the procedure by showing the differences between pre- and post- operative best-corrected visual acuity, this type of reporting is scientifically inaccurate. As demonstrated, it depends on which visual acuity chart the calculation was based on. For example, if one used the visual acuity chart in Figure 5-5 as the refractive clinic did, a patient’s BCVA was 6/9 pre-operatively and 6/4.5 post-operatively, and one would report that the patient gained three lines post-operatively. However, if one used the visual acuity chart in Figure 5-6, the patient would have gained five lines post-operatively. This also applies to calculating lines lost, but in reverse. For this reason, lines lost and gained either in uncorrected or best-corrected visual acuity were not reported. This highlights the significant inaccuracy of using different visual acuity charts and is one of the pitfalls of optometric co-management. Therefore, all the visual acuity results in this kind of clinical research reporting to date, which have not been adjusted for differences between visual acuity charts used, are not scientifically accurate. Furthermore, the reporting of lines lost and gained is all relative, simply because it depends on which visual acuity chart is used. Until such time as one particular visual acuity chart has been standardized for clinical reporting, researchers must provide information about the visual acuity chart used when reporting visual acuity, otherwise the findings are of less value.

5.12.3 Optometric Co-management Caused Deviation in Subjective Data Collection The major aspects in collecting the patient satisfaction data that deviated from the study design as a result of the optometric co-management mainly related to the way in which the

159 questionnaire was administered, and the delay in administering it. Adherence to the study design required the subjects to have their post-operative reviews on time according to specified time intervals. The patient satisfaction questionnaire was sent to subjects instead of being completed at the refractive clinic on the day immediately following their clinical post- operative assessment. This changed the study procedure to a mail-out survey, which is prone to a high non-response rate. Also, adherence to the study design required the subjects to complete the questionnaire upon receiving it, so that both the clinical data and the patient satisfaction data could be captured at the correct time. If subjects had not had their post- operative review or completed the questionnaire upon the first reminder, time was wasted while waiting for the optometrist to forward the clinical report which confirmed that the subjects had their follow-up assessment. Questionnaires were then sent again for subjects to complete. Sometimes subjects did not go to the optometrist for their review until further reminded, or the optometrist did not send off the clinical report until numerous phone calls had been made, which caused considerable delay in administering the questionnaire. In some cases, despite a number of phone calls, messages left or reminder letters sent, either the subjects only returned the completed questionnaire or only had their clinical review, or did nothing. Therefore, only clinical or questionnaire data were collected for some patients, or no data were collected after the first survey.

160

C H A P T E R 6

Results Chapter 6

6.0 Results Table 6-1. Number of subjects at each survey in the treatment and control group Treatment group Control group First survey 216 100 Missing at this survey 0 0 Second survey 110 49 Missing at this survey 106 (49%) 51 (51%) Third survey 143 Not applicable Missing at this survey 73 (34%) Not applicable Fourth survey 131 Not applicable Missing at this survey 85 (39%) Not applicable

Table 6.1 demonstrates there was 34% to 49% drop-out rate from the first survey to the subsequent follow-ups in the treatment group and 51% in the control group. As explained in the previous chapter, the control group did not undergo any treatment, therefore no further follow-up was necessary beyond the second survey.

Table 6-2. Types of data collected at each survey for the treatment group Types of First survey Second survey Third survey Fourth survey data Frequency Percent Frequency Percent Frequency Percent Frequency Percent

Clinical data + 216 100 101 46.8 108 50 90 41.7 questionnaire Clinical data - - 9 4.2 21 9.7 8 3.7 only Questionnaire - - - - 14 6.5 33 15.3 only Subtotal 216 100 110 50.9 143 66.2 131 60.6 Missing at this - - 91 42.1 34 15.7 85 39.4 survey Lost to - - 15 6.9 39 18.1 - - follow-up Total 216 100 216 100 216 100 219 100

161 Table 6-3. Types of data collected at each survey for the control group First survey Second survey Frequency Percent Frequency Percent Clinical data, 89 89 44 44 questionnaire Clinical data only 11 11 5 5 Questionnaire only - - - - Subtotal 100 100 49 49 Missing at this survey - - 51 51 Lost to follow-up - - - - Total 100 100 100 100

Tables 6-2 and 6-3 confirm the 50% drop-out rates of subjects in both the treatment and control groups. Also, there was small percentage of subjects where either only the clinical or subjective satisfaction questionnaire data were collected.

6.1 Summary of Clinical Results Research question 1 (see Method chapter page 153): From an efficacy perspective, what level of uncorrected distance visual acuity can LASIK achieve?

Overview of distance uncorrected visual acuity from 3 to 24 months post-op

50 46 45 41 40 40 38 35 34 35 31

30 3 months % 25 6 months 19 20 12 months 15 24 months 12 13 15 11 9 9 7 10 6 6 4 5 5 2 2 3 2 2 3 0 0 0 1 1 1 1 1 0 6/20 6/18 6/15 6/12 6/10 6/9 6/7.5 6/6 6/5 6/4.5

Fig. 6-1. Overview of distance UCVA achieved at 3 to 24 months post-operatively. Figure 6-1 shows that 40% of subjects achieved uncorrected distance visual acuity of 6/6 at the first and second survey. There was a slight deterioration at the third survey and

162 improvement to 46% at the fourth survey. Thirty eight percent of subjects achieved 6/4.5 at the first survey, a percentage which deteriorated at the second and third survey, and declined further to 19% at the fourth survey. The probability for this drop in percentages could be due to poor quality post-operative data under the optometric co-management scheme as detailed in Chapter 5. Other possibilities are fewer subjects responding and/or fewer subjects achieving 6/4.5 at the fourth survey, or most likely the subjects who achieved 6/4.5 were very satisfied and fewer of them returned for later survey. This speculation is statistically verified in research question 19 (see page 218-219).

Research question 2: How stable is the post-operative distance UCVA? Table 6-4. Comparison of pre-operative distance BCVA to post-operative UCVA in surveys 1 to 4 Comparison Mean N Std. t df p Deviation <0.01 Pair Pre-op BCVA 1.23 349 0.16 13.0 348 <0.001 1 Post-op UCVA at 1 st survey a 1.10 349 0.24 Pair Post-op UCVA at 1 st survey 1.04 178 0.24 0.21 177 0.83 2 Post-op UCVA at 2 nd survey a 1.03 178 0.25 Pair Post-op UCVA at 2 nd survey 1.0 103 0.25 -0.17 102 0.86 3 Post-op UCVA at 3 rd survey 1.0 103 0.27 Pair Post-op UCVA at 3 rd survey 1.0 109 0.25 2.40 108 0.02 4 Post-op UCVA at 4 th survey 0.99 109 0.25 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. Unit of measure in visual acuity is a decimal number, where 6/6 = 1.0. The smaller the decimal number the worse the visual acuity.

Table 6.4 shows that there significant change occurred between the pre-operative BCVA and post-operative UCVA at survey 1, p < 0.001, such that the pre-operative BCVA mean was higher and thus was better. There is no significant change in other survey.

163 Research question 3: How does the subjects’ pre-operative BCVA compare to their 3 months post-operative distance UCVA? How does it compare to the BCVA at baseline and 3 months in the control group? The 2(group) x 2(time) ANOVA analysis showed that there was a significant difference between the two groups, in that the treatment group had a higher mean visual acuity score than the control group at survey 1 (F 1,445 = 73.77, p < 0.001). Figure 6-2 demonstrates that the treatment group’s pre-operative BCVA was better than the 3 months post-operative UCVA,

(F 1,445 = 5.09, p = 0.03) and there was an interaction (F 1,445 = 206.39, p < 0.001). The interaction was that the control group’s BCVA was much lower at survey 1 (baseline) than that of the treatment group, but showed marked improvement at 3 months. In fact, it surpassed the 3 months post-operative UCVA of the treatment group.

Comparison of the pre-op BCVA & 3 months post-op UCVA in the

treatment group Vs BCVA at 1st & 2nd survey in the control group Fig. 6-2. Comparison of the mean 1.3 Pre -op BCVA scores of distance visual acuity

1.2 between the treatment and control

3-month BCVA groups at survey 1 and 2. Unit of 1.1 measure in visual acuity is a decimal

1.0 Post -op UCVA at 3 months number, where 6/6 = 1.0. The smaller the decimal number the worse the .9 Treatment group visual acuity. Note, the apparent

Estimated Marginal Means Estimated Marginal Baseline BCVA .8 Control group declined in the treatment group reflect Survey 1 Survey 2 the difference between BCVA and DISTANCE VISUAL ACUITY UCVA.

Possible explanations are that the pre-operative BCVA was meticulously refracted by the surgeon to achieve the best possible corrected visual acuity during the consultation prior to surgery, and thus the pre-operative BCVA was better; or the finding could be due to poor quality of post-operative data under the optometric co-management scheme as outlined in Chapter 5; or simply the post-operative UCVA was not as good as the pre-operative BCVA. As for the control group, 38 subjects had new glasses and/or contact lenses prescribed at the end of the first survey, which allowed them to see better at the second survey.

164 Research question 4: From a safety perspective, what level of distance BCVA can LASIK achieve?

Overview of distance BCVA from 3 to 24 months post-op

60 57 52 52 50 43

40 32 33 3 months 29 % 30 26 6 months 12 months 20 24 months 10 8 9 9 10 7 5 7 2 2 3 1 1 2 2 1 1 0 6/10 6/9 6/7.5 6/6 6/5 6/4.5 6/4 6/3

Fig. 6-3. Overview of distance BCVA achieved 3 to 24 months post-operatively.

Figure 6-3 shows that 32% of subjects achieved 6/6 at the first survey, there was some deterioration at the second and third surveys, but improvement to 43% at the fourth survey. Fifty seven percent of subjects achieved 6/4.5 at the first survey, there was slight deterioration at the second and third surveys, and even further to 33% at the fourth survey. This drop in percentages could again be due the poor quality post-operative data under the optometrist co- management as outlined in Chapter 5; or it could be attributable to fewer subjects responding and/or fewer subjects achieving 6/4.5 at survey 4; or most likely the subjects achieving 6/4.5 were very satisfied and fewer of them returned for later surveys.

Research question 5: How stable is the post-operative distance BCVA? Table 6-5. Comparison of distance pre- and post-operative BCVA at surveys 1 to 4 Comparison Mean N Std. t df p Deviation < 0.01 Pair Pre-op BCVA 1.23 349 0.16 5.40 348 <0.001 1 Post-op BCVA at 1 st survey a 1.17 349 0.19 Pair Post-op BCVA at 1 st survey 1.15 177 0.19 -0.004 176 1.0 2 Post-op BCVA at 2 nd survey a 1.15 177 0.22 Pair Post-op BCVA at 2 nd survey 1.13 102 0.19 0.40 101 0.69 3 Post-op BCVA at 3 rd survey 1.13 102 0.21

165 Comparison Mean N Std. t df p Deviation < 0.01 Pair Post-op BCVA at 3 rd survey 1.16 109 0.20 2.30 108 0.02 4 Post-op BCVA at 4 th survey 1.12 109 0.19 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. Unit of measure in visual acuity is a decimal number, where 6/6 = 1.0. The smaller the decimal number the worse the visual acuity.

Table 6-5 shows significant change occurring between the pre- and post-operative BCVA at survey 1, p < 0.001, such that the pre-operative BCVA mean was higher, thus better. There was no statistically significant change in the other surveys.

Another way to demonstrate the LASIK procedure’s safety is to assess the number of line(s) lost and gained of BCVA from pre- to post-operatively. This form of reporting is often seen in journal publications and conference presentations. However, the problems outlined in Chapter 5, page 151-154 may have affected the accuracy of the data. Therefore, reporting of lines lost or gained BCVA had to be excluded. From a scientific clinical reporting perspective, this is a problematic area in this kind of study, but not a single study so far has discussed its significance and how it affects the accuracy of findings. Until such time as one particular visual acuity chart has been standardized for clinical research reporting, researchers must provide information about the visual acuity chart used when reporting visual acuity, otherwise the findings are of less value.

Research question 6: How does subjects’ pre- and 3 months post-LASIK distance BCVAs compare to the BCVA at baseline and 3 months in the control group? The 2(group) x 2(ANOVA) analysis in figure 6-4 showed that there was a significant difference between the two groups, in that the treatment group had a higher mean BCVA score than the control group (F 1,445 = 153.53, p < 0.001). Figure 6-4 demonstrates that the treatment group’s pre-operative pre-BCVA was better but declined slightly at 3 months post-operatively

(F 1,445 = 52.94, p < 0.001) and there was an interaction (F 1,445 = 145.74, p < 0.001). The interaction was that the control group’s BCVA was much lower at the first survey than that of the treatment group but showed marked improvement at survey 2.

166 Comparison of the mean scores of pre & post-op. BCVA in treatment grp. Vs. BCVA at survey 1 & 2 in control grp. 1.3 Pre-op. BCVA Fig. 6-4. Unit of measure in 1.2 visual acuity is decimal 1.1 3-month post -op. BCVA number, where 6/6 = 1.0, 3-month BCVA 1.0 smaller the decimal number

.9 worse the visual acuity. Treatment group

Estimated Marginal Means Estimated Marginal Baseline BCVA .8 Control group survey 1 survey 2 DISTANCE BCVA

A possible explanation for this, as mentioned earlier, may be due to poor quality post- operative data under the optometrist co-management as outlined in Chapter 5, page 151-154. If this is true, there is doubt whether the post-operative BCVA was really best or perhaps it should be labelled aided visual acuity. Or simply the post-operative BCVAs were not as good as the pre-operative BCVA. As for the control group, the subjects with their newly prescribed glasses and/or contact lenses were able to see better at survey 2.

Research question 7: For monovision corrected subjects, what level of uncorrected near visual acuity can LASIK achieve?

Overview of uncorrected near visual acuity from 3 to 24 months post-op

68 70 58 60

50 43 44 3 months 40 33 6 months % 28 30 12 months 23 21 19 24 months 20 13 9 8 8 5 5 6 6 10 3 2 3 0 N14 N12 N10 N8 N6 N5 N4.5

Fig. 6-5. Unit of measure where N4.5 is the best possible near visual acuity.

Figure 6-5 shows that 58% and 68% of subjects achieved near visual acuity of N4.5 at surveys 1 and 2 respectively, but deteriorated to just over 40% at surveys 3 and 4. It was speculated

167 that this drop in visual acuity could affect the patient satisfaction, which is statistically verified in research question 19 (see page 218-219).

Research question 8: How stable is the post-operative uncorrected near visual acuity? Table 6-6. Comparison of post-operative uncorrected near visual acuity (UCNVA) at surveys 1 to 4 Comparison Mean N Std. t df p Deviation <0.01 Pair P/op near UCNVA at 1 st survey a 3.60 46 2.35 -0.41 45 0.68 1 P/op near UCNVA at 2 nd survey 3.65 46 2.25 Pair P/op near UCNVA at 2 nd survey a 3.10 33 2.37 -1.33 32 0.19 2 P/op near UCNVA at 3 rd survey 3.57 33 3.41 Pair P/op near UCNVA at 3 rd survey 3.60 38 3.51 0.94 37 0.36 3 P/op near UCNVA at 4 th survey 3.30 38 2.61 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. Unit of measure in near visual acuity where 4.5 is the best level possible.

Table 6-6 shows no significant change occur in the post-operative uncorrected near visual acuity from surveys 1 to 4, p > 0.01. Unfortunately, the near visual acuity pre-LASIK, baseline and at 3 months in the control group were not extracted from the subjects’ files, and therefore comparison between the two groups was not possible.

Research question 9: Repeated measures study is known to have different response rates in each survey. Thus, is there any significant difference in post-operative uncorrected distance, near visual acuity and best-corrected distance visual acuity between subjects who returned for more than one survey and those who returned for only one survey? The independent samples t-test analysis showed that there were no statistically significant differences in post-operative uncorrected distance, near or best-corrected distance visual acuity at survey 1 between patients who returned for more than one survey and those who returned for only one survey (see Appendix XVIII). The lack of differences between the two

168 groups could be due to the small number of subjects who did not return (e.g. 24 subjects did not return versus 191 subjects did return) and type I error.

Research question 10: From an accuracy perspective, how does the intended surgical goal compare to that achieved? The frequency of categories shows that based on the 3 months post-operative surgical results, where all 216 subjects returned for their review, there were a few discrepancies between the intended and the post-operative achieved surgical results (see Appendix XIX).

At survey 1, five subjects had unintentionally become monovision instead of emmetropic as planned in one of their eyes. These subjects were of presbyopic or near presbyopic age and elected to leave the results as they were. Three subjects had monovision corrected in one of their eyes, but disliked the result and had enhancement to become emmetropic. One subject had unintentionally became emmetropic instead of monovision as planned in one eye, but the subject elected to leave the result as it was. Unfortunately, not all the same subjects returned in surveys 2, 3 and 4, and therefore, it was not possible to track and compare the intended and the achieved surgical results. However, other clinical data such as visual acuity and residual refractive errors showed that the subjects’ surgical results remained the same thereafter. It was speculated that subjects with unintended results and/or who required enhancement to modify their surgical outcome might be dissatisfied, which will be statistically verified in research question 35 (see page 237-238).

Research question 11: What are the ranges of residual refractive errors? How stable are they? Table 6-7. Residual refractive errors (other than zero) of the right and left eye at 3 to 24 months post-operatively 3 months 6 months 12 months 24 months Right Left Right Left Right Left Right Left Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) No residual 53 53 40 52 46 54 49 45 refractive error Myopic 23 23 34 19 31 25 35 30

169 3 months 6 months 12 months 24 months Right Left Right Left Right Left Right Left Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Eye (%) Hyperopic 16 17 17 20 16 11 11 18 Astigmatism 9 7 9 10 8 10 5 7 Total 100 100 100 100 100 100 100 100

Table 6-7 shows in the averages of four surveys, 49% of the eyes were refractive error free and 51% had residual refractive errors: 28% were myopic; 16% were hyperopic; and 8% were astigmatic. It was speculated that subjects who had residual refractive errors, especially greater than one diopter in either spherical, cylindrical or both might be less satisfied, which is statistically verified in research question 22 (see page 221-222).

Distribution of residual myopic spherical errors

Percentage of Residual Myopic Sphere from 3 to 24 Months Post-op

70 64 62 59 60 56

50 > +1D 40 > +0.5D % 0 residual 30 > -0.5D 21 19 18 > -1D 20 15 8 8 9 10 4 3 1 0 2 2 1 1 1 0 3 months N=277 6 months N=135 12 months N=156 24 months N=115 Fig. 6-6. Distribution of residual myopic spherical errors from the first to fourth survey.

Figure 6-6 shows that the procedure was effective in treating myopic sphere. There was a small amount of over-correction (circled in red) at 3 and 6 months, but it reduced to minimal at 24 months. This is consistent with clinical observation where over-corrections are intended to allow room for regression during the healing process. There were persistent under- corrections (circled in blue) throughout all four surveys, more so at 24 months post- operatively. This provides an excellent insight as to the efficacy and the stability of procedure (see Appendix XXa-d for the individual histograms of 3, 6, 12 and 24 months).

170 Evaluation of stability of residual myopic spherical errors from 3 to 24 months Table 6-8. Post-operative residual myopic spherical errors at surveys 1 to 4 Comparison Mean N Std. t df p Deviation <0.01 Pair Post-op sphere at 1 st survey a -0.02 135 0.35 2.26 134 0.03 1 Post-op sphere at 2 nd survey -0.06 135 0.36 Pair Post-op sphere at 2 nd survey a -0.08 77 0.34 1.07 76 0.30 2 Post-op sphere at 3 rd survey -0.11 77 0.31 Pair Post-op sphere at 3 rd survey -0.11 80 0.32 1.44 79 0.15 3 Post-op sphere at 4 th survey -0.28 80 0.97 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. The unit of measure is in minus decimal number, the bigger the number the larger the residual myopic spherical error.

Table 6-8 shows that there was no significant change in post-operative residual myopic spherical errors from surveys 1 to 4 (p is > 0.01), despite the persistent under-correction shown in Figure 6-6. Although the means at surveys 1 and 2 appear to be smaller than at survey 3 and 4, this is due to the overcorrection (+) and undercorrection (-) cancelling each other out, as indicated in Figure 6-6.

Distribution of residual minus cylindrical errors

Percentage of Residual Minus Cylinder from 3 to 24 Months Post-op

80 72 70 65 68 65 60 50 > +1D > +0.5D % 40 0 residual > -0.5D 30 21 18 19 > -1D 20 15 10 5 4 3 4 0 0 0 0 0 0 0 0 0 3 months N=277 6 months N=135 12 months N=156 24 months N=116

Fig. 6-7. Distribution of residual minus cylindrical errors from the first to fourth survey.

171 Figure 6-7 shows the procedure to be effective in treating minus cylinder errors, but there was persistent under-correction (circled in blue) throughout all four surveys. This provides an excellent insight into the efficacy and the stability of the procedure. See appendix XXIa-d for the individual histograms of 3, 6, 12 and 24 months.

Evaluation of stability of residual minus cylindrical errors at surveys 1 to 4 Table 6-9. Post-operative residual minus cylindrical errors at surveys 1 to 4 Comparison Mean N Std. Deviation t df p <0.01 Pair Post-op cylinder at 1 st survey a -0.23 115 0.37 -0.09 114 0.93 1 Post-op cylinder at 2 nd survey -0.22 115 0.34 Pair Post-op cylinder at 2 nd survey a -0.19 67 0.29 0.17 66 0.86 2 Post-op cylinder at 3 rd survey -0.20 67 0.39 Pair Post-op cylinder at 3 rd survey -0.18 63 0.29 -0.37 62 0.72 3 Post-op cylinder at 4 th survey -0.17 63 0.31 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. The unit of measure is in minus decimal number, the bigger the number the larger the residual minus cylindrical error.

Table 6-9 shows that there was no significant change in the post-operative residual minus cylinder errors from 3 to 24 months (p > 0.01) despite the persistent under-correction shown in Figure 6-7.

Residual hyperopic spherical errors

Percentage of Residual Hyperopic Sphere from 3 to 24 Months Post -op . 60 60

50 45 42 40 > +1D > +0.5D % 30 24 26 0 residual 21 21 > -0.5D 20 15 13 > -1D 11 10 10 9 7 10 6 5 7 5 3 5 0 3 months N=67 6 months N=39 12 months N=45 24 months N=20

Fig. 6-8. Distribution of residual hyperopic spherical errors from the first to the fourth survey.

172 Figure 6-8 shows that the procedure was effective in treating hyperopic sphere, perhaps not as effective as with myopic sphere. There was a tendency to moderate overcorrection (circled in red) and small under-correction (circled in blue), the overcorrections being more prominent at 6 months post-operatively. Some of the overcorrections were intended to allow room for regression during the healing process. By the 12 to 24 months surveys these effects had reduced by half (see Appendix XXIIa-d for the individual histograms of 3, 6, 12 and 24 months).

Evaluation of stability of residual hyperopic spherical errors at surveys 1 to 4 Table 6-10. Post-operative residual hyperopic spherical errors at surveys 1 to 4 Comparison Mean N Std. Deviation t df p <0.01 Pair Post-op sphere at 1 st survey a -0.14 39 0.61 2.22 38 0.03 1 Post-op sphere at 2 nd survey -0.50 39 0.88 Pair Post-op sphere at 2 nd survey a -0.42 23 1.0 -1.93 22 0.07 2 Post-op sphere at 3 rd survey -0.02 23 0.79 Pair Post-op sphere at 3 rd survey -0.16 16 0.63 0.00 15 1.00 3 Post-op sphere at 4 th survey -0.16 16 0.60 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. The unit of measure is in decimal number, the bigger the decimal number the larger the residual hyperopic spherical error.

Table 6-10 shows that there was no significant change in the post-operative residual hyperopic spherical errors from surveys 1 to 4 (p > 0.01) despite the under and overcorrection shown in Figure 6-8. Although the means at surveys 1 and 3 appear to be smaller than in other surveys, this is due to the overcorrection (+) and undercorrection (-) cancelling each other as indicated in Figure 6-8.

173 Residual plus cylindrical errors

Percentage of Residual Plus C ylinder from 3 to 24 Months Post -op .

70 63 60 60 56 50 46 > +1D 40 > +0.5D % 31 28 0 residual 30 25 22 > -0.5D 20 > -1D 10 10 3 6 0 0 0 0 2 0 0 0 0 0 3 months N=67 6 months N=39 12 months N=45 24 months N=36 Fig. 6-9. Shows residual plus cylindrical errors from the first to fourth survey.

Figure 6-9 shows that the procedure was effective in treating plus cylinder errors, but there was a tendency of under-correction (circled in blue) throughout all four surveys. This finding is similar to that for minus cylinder errors, but it is much greater with the plus cylinder (see Appendix XXIIIa-d for the individual histograms of 3, 6, 12 and 24 months).

Evaluation of stability of residual plus cylindrical errors at surveys 1 to 4 Table 6-11. Post-operative residual plus cylindrical errors at surveys 1 to 4 Comparison Mean N Std. t df p Deviation <0.01 Pair Post-op cylinder at 1 st survey a 0.18 30 0.32 -1.90 29 0.07 1 Post-op cylinder at 2 nd survey a 0.33 30 0.37 Pair Post-op cylinder at 2 nd survey 0.29 20 0.37 0.53 19 0.60 2 Post-op cylinder at 3 rd survey 0.25 20 0.38 Pair Post-op cylinder at 3 rd survey 0.20 27 0.32 -2.09 26 0.05 3 Post-op cylinder at 4 th survey 0.35 27 0.40 Note: (a) Means for the same measure differ from pair to pair because the composition of the group differed slightly from one survey to another. The unit of measure is in decimal number, the bigger the decimal number the larger the residual hyperopic cylindrical error.

Table 6.11 shows that there was no significant change in the post-operative residual plus cylindrical errors at surveys 1 to 4 (p > 0.01), despite the persistent under-correction shown in Figure 6-9.

174 Research question 12: Repeated measures study is known to have different response rates in each survey. Thus, is there any significant difference in residual refractive errors between subjects who returned for more than one survey and those who returned for only one survey? The independent samples t-test analysis showed that there was a statistically significant difference with the residual minus cylinder only, such that the subjects who returned for only one survey had less residual minus cylindrical error at survey 1, p < 0.001 (mean = -0.04 vs. - 0.19; sd = 0.13 vs. 0.31). This statistically confirmed the speculation that fewer subjects who achieved better visual acuity and in turn had less residual refractive error would return for later surveys.

6.2 Summary of Subjective or Patient Satisfaction Questionnaire Results The results in this section are presented by the research questions followed by illustrations of how each of them was defined, with the statistical analyses of the individual patient satisfaction question in the questionnaire of the treatment group.

Research question 13: How do subjects learn about LASIK, why do they want to have LASIK and what do they want to achieve? The first section of the treatment group questionnaire consisted of five questions which were unique to the treatment group, to establish subjects’ characteristic profiles and their goals in having LASIK. The results are as follows: Treatment group Question 1. How did you first learn about the LASIK procedure?

How did you first learn about the LASIK procedure? 70 60 60 56 58 57 Media 50 Medical literature Ophthalmologist 40 Optometrist % General practitioner 30 Word of mouth from ex-patient 18 19 Family, relative & friend 20 15 17 14 13 Media & word of mouth from ex-patient 11 11 10 Media & family, relative & friend Work in the same building 0 Private health fund 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=120 N=123

Fig. 6-10. Overview of responses at all 4 surveys.

175 Figure 6-10 shows that on average 58% of the subjects learned about the LASIK procedure from the media; followed by family, relative or friend (17%); then word of mouth from ex- patients (12%), and the minor percentages were from other categories. The characteristics of the study sample remained fairly constant across the four surveys.

Treatment group Question 2. Who referred you to this centre or surgeon?

Who referred you to this centre or surgeon? 70 60 52 50 46 44 44 Myself 40 Ophthalmologist % Optometrist 30 General practitioner 20 Other medical health allies professional 19 17 20 14 15 Word of mouth from ex-patient 13 12 12 10 10 11 Family, relative & friend 9 9 7 10 7 7 0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=120 N=123

Fig. 6-11. Overview of responses at all 4 surveys.

Figure 6-11 shows that on average 46% of the subjects chose the centre themselves; next most common was word of mouth from ex-patient/s (average 17%); then general practitioner or family, relative or friend (average 11%); and then optometrists (average 10%). This is probably due to the fact that as the procedure has become more publicised more people know about it and/or recommend it to their relatives and friends. Despite the 50% dropout rate from 3 to 6 months, the samples remained very similar in composition from 3 to 24 months post- operatively.

Treatment group Question 3. What was the PRIME objective for having the surgery?

What was the PRIME object ive for having the surgery? 70 63 62 59 60 54 Improve overall vision 50 Improve un-aided distance vision Improve un-aided near vision 40 Restore normal sight % Disliked glasses and/or contact lenses 30 Intolerant to glasses and/or contact lenses 20 Wanted a better life style 18 18 20 16 For sports & recreational reasons Cosmetic reason 10 5 5 5 7 Disliked glasses and/or contact lenses with sports 4 4 2 3 0 Wanted a better life style & cosmetic reason 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123

Fig. 6-12. Overview of responses at all 4 surveys.

176 Figure 6-12 shows that on average 60% of the subjects chose LASIK because they disliked glasses and/or contact lenses; this reason was followed by wanting to improve or restore overall vision (average18%); then for sports and recreational reasons (average 4.5%); and wanting a better lifestyle (average 4.3%). The remaining categories each averaged less than 4.3%. The responses remained very similar in all four surveys.

Treatment group Question 4. What were the other reason(s) for having the surgery?

What were the other reason(s) for having the surgery? No other reason 60 54 54 Stranded or restricted w ith gls/c.l. 50 51 50 Disliked/intolerant to gls/c.l.

40 Convenient, a better life style, better un-aided vision & recreational reasons Increase confindence/self esteem % 30 26 26 22 22 Cost saving & freedom from gls/c.l. 20 Seeing the results from ex-patients 14 12 9 8 10 8 10 Occupational reason 4 4

0 Cosmetic reason 1st survey 2nd survey 3rd survey 4th survey Others N=203 N= 92 N=116 N=114

Fig. 6-13. Overview of responses at all 4 surveys.

Figure 6-13 shows that on average 52% of the subjects had no other reason; the combination of convenience, better lifestyle, better unaided vision and recreational reasons was second highest (average 24%); followed by dislike or intolerance for glasses and/or contact lenses and cosmetic reasons (average 11%). The remaining categories averaged less than those reasons. The responses remained similar in all four surveys.

Treatment group Question 5. What was your PRIME desired end result?

What was your PRIME desired end result? 60 52 51 50 48 50

40 36 Better overall vision without gls/c.l. 28 30 % 30 28 Better distance vision without gls/c.l. Better near vision withought gls/c.l. Occupation & recreation without gls/c.l. 20 17 14 Eliminate gl/c.l. altogether Reduce number of pair of glasses 8 8 8 10 5 6 1 2 3 1 1 0 1st survey 2nd survey 3rd survey 4th survey N=213 N= 100 N=121 N=123

Fig. 6-14. Overview of responses at all 4 surveys.

177 Figure 6-14 shows that on average 50% of the subjects wanted to achieve better distance vision without glasses and/or contact lenses; followed by better overall vision without glasses and/or contact lenses (average 31%); then the desire to eliminate glasses and/or contact lenses altogether (average 12%); better near vision without glasses and/or contact lenses (average 5.5%). The remaining categories averaged less than 5.5%. Small differences became apparent from survey 3 to survey 4, while the study sample remained very similar.

Research question 14*: With the questions that are comparable between the treatment and control group, how do the subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual activities, overall quality of life, treatment outcome and satisfaction of treatment) compare between the two groups? (Note, this is a central research question) The second section of the treatment group questionnaire consisted of four questions designed to be comparable between the treatment and control groups. The questions assessed subjects’ post-operative ocular symptoms, self-perceived rating of visual abilities, visual improvement in performing different activities, and the effect on overall quality of life. The results in this section are presented by the research questions followed by illustrations of how they were defined, with the statistical analyses of the individual patient satisfaction question in the questionnaires of the treatment and control groups, and finally the comparison between the treatment and control groups. They are as follows:

Treatment group Question 6a. Are you currently having any pain or discomfort?

Are you currently having any pain or discomfort?

100 90 88 88 86 90 80 70 60 % 50 None 40 Mild Moderate 30 Severe 20 12 8 9 8 10 3 1 1 2 2 0 1 1 0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=123 N=123

Fig. 6-15. Overview of responses at all 4 surveys.

178 Figure 6-15 shows that on average 88% of the subjects had no pain or discomfort; and on average 9% reported a mild level of pain. Small percentages were distributed throughout the remaining categories. The responses remained almost identical in all four surveys.

Control group Question 2a. While wearing your glasses and/or contact lenses, do you have any pain or discomfort?

While wearing yours glasses and/or contact lenses, do you have any pain or discomfort?

97 100 91

80 71 75

60 None % Mild 40 25 Moderate 20 1414 Severe 2 4 2 0 0 3 0 0 0 0 1st survey 1st survey 2nd survey 2nd survey Gls N=46 C.L. N=7 Gls N= 38 C.L. N=4

Fig. 6-16. Overview of responses in both surveys.

Figure 6-16 shows that on average 94% of the subjects had no pain or discomfort; an average of 12% reported a moderate level of pain; and an average of 8% reported a mild level of pain. Only 2% of subjects who wore glasses indicated that they had a severe level of pain, caused mainly by the frame on the face, nose and around the ears. More subjects who wore contact lenses reported a moderate level of pain or discomfort.

Comparison of pain between the treatment and control groups at surveys 1 and 2: A 2(group) x 2(time) ANOVA analysis in figure 6-17 showed that there was no significant

difference between the two groups (F 1, 145 = 0.5, p = 0.5), no significant change over time (F 1,

145 = 2.1, p = 0.1) and no interaction (F 1, 145 = 1.1, p = 0.3).

Comparison of the mean pain scores between the treatment and control group .4

Fig. 6-17. Unit of measurement .3 is in a scale, where 0 = none

.2 and 5 = severe.

Treatment group Estimated Marginal Means Estimated Marginal .1 Control group Survey 1 Survey 2 Pain

179 Treatment group Question 6b. Are you currently having any irritation? Are you currently having any irritation? 70 67 68 70 64

60

50

40 None % 27 30 25 24 24 Mild Moderate 20 Severe

5 4 4 4 5 10 4 2 2 0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=123 N=123

Fig. 6-18. Overview of responses at all 4 surveys.

Figure 6-18 shows that on average 67% of the subjects had no irritation; some had a mild level of irritation (average 25%), and a few reported moderate to severe levels of irritation (average 3.8% each). The responses remained almost identical in all four surveys.

Control group Question 2b. While wearing your glasses and/or contact lenses, do you have any irritation?

While wearing yours glasses and/or contact lenses, do you have any irritation?

90 82 80 73 75 70 60 50 None % 40 Mild 29 29 29 30 25 Moderate 17 20 11 14 13 Severe 3 10 0 3 0 0 0 1st survey 1st survey 2nd survey 2nd survey Gls N=46 C.L. N=7 Gls N= 38 C.L. N=4

Fig. 6-19. Overview of responses in both surveys.

Figure 6-19 shows that on average 65% of the subjects had no irritation; and some had a mild level of irritation (average 21%). Moderate and severe levels of irritation were only reported at the first survey, and were associated mainly with those who wore contact lenses.

180 Comparison of irritation between the treatment and control groups at surveys 1 and 2: A 2(group) x 2(time) ANOVA analysis in figure 6-20 showed that there was no significant difference between the two groups (F 1, 145 = 1.8, p = 0.2), no significant change from over time

(F 1,145 = 1.7, p = 0.2) and no interaction (F 1, 145 = 0.3, p = 0.6).

Comparison of the mean irritation scores between

the treatment and control group .9 Fig. 6-20. Unit of measurement .8 is in a scale, where 0 = none and 5 = severe. .7

.6

.5 Treatment group Estimated Marginal Means Estimated Marginal .4 Control group Survey 1 Survey 2

Irritation

Treatment group Question 6c. Are you currently having any glare?

Are you currently having any glare?

60 55 52 51 49 50 40 37 40 33 31 % 30 None Mild 20 Moderate 12 9 Severe 6 6 6 7 5 10 3

0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=123 N=123

Fig. 6-21. Overview of responses at all 4 surveys.

Figure 6-21 shows that on average 52% of the subjects had no glare; about a third reported a mild level of glare (average 35%), an average of 9% had moderate glare and an average of 5% reported a severe level of glare. The responses remained very similar in all four surveys.

181 Control group Question 2c. While wearing your glasses and/or contact lenses, do you have any glare?

While wearing yours glasses and/or contact lenses, do you have any glare?

90 82 80 75 70 65 60 50 43 None % Mild 40 2929 30 22 25 Moderate 16 20 11 Severe 3 10 2 0 0 0 0 0 1st survey 1st survey 2nd survey 2nd survey Gls N=46 C.L. N=7 Gls N= 38 C.L. N=4

Fig. 6-22. Overview of responses in both surveys.

Figure 6-22 shows that on average 66% of the subjects reported no glare and on average 20% had a mild level of glare. A moderate level of glare was only reported at the first survey, slightly more by those who wore contact lenses.

Comparison of glare between the treatment and control groups at surveys 1 and 2: A 2(group) x 2(time) ANOVA analysis in figure 6-23 showed a significant difference between the two groups (F 1,145 = 6.5, p = 0.01), in that the treatment group had significantly higher mean glare scores than the control group. There was an overall significant improvement in both groups from survey 1 to 2 (F 1,145 = 7.4, p = 0.007), and there was no interaction (F1,145 = 0.02, p = 0.90).

Comparison of the mean glare scores between the treatment and control group 1.4

1.2 Fig. 6-23. Unit of measure is in a scale, where 0 = none 1.0 and 5 = severe.

.8

.6

Estimated Marginal Means Estimated Marginal Treatment group

.4 Control group Survey 1 Survey 2

Glare

182 Treatment group Question 6d. Are you currently having any dry eye?

Are you currently having any symptoms of dry eye?

60 50 50 47 50 44

40 33 31 31 29 % 30 None Mild 20 15 14 Moderate 12 11 11 9 Severe 8 7 10

0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=123 N=123

Fig. 6-24. Overview of responses at all 4 surveys.

Figure 6-24 shows that on average 48% of the subjects had no dry eye, an average of 31% had mild dry eye, an average of 13% had moderate dry eye and average of 9% reported severe dry eye. The responses remained almost identical in all four surveys. Interestingly, out of all four subcomponents of ocular symptoms in Question 6, dry eyes, glare and irritation respectively were the symptoms most frequently complained about.

Control group Question 2d. While wearing your glasses and/or contact lenses, do you have any dry eye?

While wearing yours glasses and/or contact lenses, do you have any dry eye?

100 92 87 80 75

60 None % 43 43 Mild 40 25 Moderate 20 14 Severe 7 5 4 2 0 3 0 0 0 0 1st survey 1st survey 2nd survey 2nd survey Gls N=46 C.L. N=7 Gls N= 38 C.L. N=4

Fig. 6-25. Overview of responses in both surveys.

183 Figure 6-25 shows that on average 74% of the subjects reported no dry eyes, an average of 25% had moderate dry eyes, an average of 19% had mild dry eye and an average of 8% had severe dry eye. Moderate and severe dry eyes were mainly associated with those who wore contact lenses, and were only prominent at the first survey.

Comparison of dry eyes between the treatment and control groups at surveys 1 and 2: A 2(group) x 2(time) ANOVA analysis in figure 6-26 showed that there was a significant difference between the two groups (F 1,144 = 20.7, p < 0.001) in that the treatment group had significantly higher mean dry eye scores than the control group. There was no significant change over time (F 1,144 = 2.6, p = 0.1) and no interaction (F 1,144 = 2.6, p = 0.1).

Comparison of the mean dry eye scores between the treatment and control group 1.6

1.4

1.2

1.0

.8

.6

.4

Estimated Marginal Means Estimated Marginal .2 Treatment group

0.0 Control group Survey 1 Survey 2

Dry eye

Fig. 6-26. Unit of measure is in a scale, where 0 = none and 5 = severe.

All four comparisons above show that these ocular symptoms are common occurrences to both groups, which may suggests that the symptoms were pre-existing for the LASIK subjects, but glare and dry eye may have exacerbated post-LASIK.

184 Treatment group Question 7a. How do you rate your unaided vision in distance?

How do you rate your un-aided vision in distance?

50 49 46 46 44 Scale of 1 = inability to perform the activity due to visual difficulty 40 Scale of 2

32 Scale of 3 30 30 Scale of 4 25 24 % Scale of 5 20 20 Scale of 6 14 15 Scale of 7 11

10 Scale of 8

Scale of 9 0 Scale of 10 = perfect, no problem 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123 Fig. 6-27. Overview of responses at all 4 surveys.

Figure 6-27 shows that on average 46% of the subjects rated their unaided distance vision 10 out of 10, followed by 9 out of 10 (average 28%); then 8 out of 10 (average 15%). A small percentage of the subjects gave lower ratings. If one considers a rating of 5 out of 10 to be unacceptable, the following subjects who gave a rating of 5 and their clinical details are of interest (see Appendix XXIV for table): Seven subjects could not adapt to monovision; three of these were moderate to high myopes pre-operatively and did not achieve ideal UCVA post-operatively, had lost lines of BCVA; two were moderate to high hyperopes pre-operatively who did not achieve ideal UCVA post- operatively, one had severe dry eyes and the other elected not to have enhancement.

Control group Question 4a. How do you rate your aided vision in distance?

How do you rate your aided vision in distance?

70 Scale of 1 = inability to perform 65 the activity due to visual difficulty Scale of 2 60

Scale of 3

50 47 Scale of 4

40 Scale of 5 % Scale of 6 30

Scale of 7 20 18 16 18 Scale of 8 10 10 Scale of 9

0 Scale of 10 = perfect, no problem 1st survey N=49 2nd survey N=40 Fig. 6-28. Overview of responses in both surveys.

185 Figure 6-28 shows that on average 56% of the subjects rated their distance vision 10 out of 10, followed by 8 out of 10 (average 18%), then 9 out of 10 (average 13%). Eighteen percent more subjects rated their distance vision 10 out of 10 in the second survey. A small percentage of subjects gave a lower rating, even smaller in the second survey. This was probably due to improvement of vision with their newly prescribed glasses and/or contact lenses.

Comparison between subjects’ ratings of distance vision in the treatment and control groups at surveys 1 and 2: A 2(group) x 2(time) ANOVA analysis in figure 6-29 showed that there was no significant difference between the two groups (F 1,142 = 0.0, p = 1.0). There was overall improvement in both groups, more in the control group from survey 1 to 2, (F 1,142 = 7.02, p = 0.009) and there was no interaction (F 1,142 = 2.01, p = 0.16).

Comparison of the subjects’ perception of their distance Vision between the treatment and control group 9.3

Fig. 6-29. Unit of measure is 9.2 Dist VA at 2 nd survey in control group in a scale wher e 1 = inability 9.1

st to perform the activity due to 9.0 Dist VA at 1 survey in treatment group visual difficulty and 10 = nd 8.9 Dist VA at 2 survey in treatment group perfect, no problem. 8.8 Treatment group Estimated Marginal Means Estimated Marginal Dist VA at 1 st survey in control group 8.7 Control group Survey 1 Survey 2 RATING OF DISTANCE VISUAL ACUITY (Q 7a)

Treatment group Question 7b. How do you rate your unaided vision at near or close work?

How do you rate your un-aided vision at near or close work? 50 50

44 44 42 Scale of 1 = inability to perform the activity due to visual difficulty 40 Scale of 2

Scale of 3

30 Scale of 4

% Scale of 5 21 19 20 18 Scale of 6 15 15 15 Scale of 7 11 12 10 Scale of 8

Scale of 9

0 Scale of 10 = perfect, no problem 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=122 Fig. 6-30. Overview of responses at all 4 surveys.

186 Figure 6-30 shows that on average 45% of the subjects rated their unaided near vision to be 10 out of 10, followed by 9 out of 10 (average 17%) and 8 out of 10 (average 14%). More subjects gave lower ratings in this question compared than in the previous Question 7a, which suggests that unaided near vision was more problematic to post-LASIK subjects. In fact, 16% (average of 4 surveys) of the subjects rated their near vision less than or equal to 5 out of 10. When this finding was compared with the subjects’ clinical data, only four subjects had less desirable unaided near visual acuity, two had emmetropic correction and could read N10 print size; and two had monovision correction and could read N12 and N14 print size. This suggests that subjectively, subjects rated their unaided near vision to be worse than their clinical results. The responses remained similar in four surveys, with slightly more subjects rating unaided near vision at 10 out of 10 at the fourth survey. This provides good insight into the long-term effect of the procedure with this visual task.

Control group Question 4b. How do you rate your aided vision at near or close work?

How do you rate your aided vision at near or closework?

60 Scale of 1 = inability to perform the activity due to visual difficulty 51 Scale of 2 50 Scale of 3

Scale of 4 40 37

Scale of 5 % 30 Scale of 6

18 20 18 Scale of 7 15 15

Scale of 8 10 Scale of 9

0 Scale of 10 = perfect, no problem 1st survey N=49 2nd survey N=39

Fig. 6-31. Overview of responses in both surveys.

Figure 6-31 shows that on average 44% of the subjects rated their near vision or close work to be 10 out 10, then 9 out of 10 (average 17%) and 8 out of 10 (average 17%). A small percentage of subjects gave a lower rating, even smaller at the second survey. The finding is

187 comparable to that of the treatment group, suggesting that vision at near or close work was a problematic aspect for the control group as well as the treatment group, and that the lower rating in the treatment group could possibly represent a pre-existing factor.

Comparison between subjects’ ratings of near vision in the treatment and control groups at first and second survey: A 2(group) x 2(time) ANOVA analysis in figure 6-23 showed that there was no significant difference between the two groups (F 1,141 = 0.17, p = 0.68). There was no change from survey

1 to 2 (F 1,141 = 0.37, p = 0.55) and no interaction (F 1,141 = 0.16, p = 0.69).

Comparison of the subjects’ perception of their near vision

between the treatment and control group 8.5

Near VA at 1 st survey in treatment group nd 8.4 Near VA at 2 survey in treatment group

8.3 Near VA at 2 nd survey in control group

8.2 Near VA at 1 st survey in control group Treatment group

Estimated Marginal Means Estimated Marginal 8.1 Control group Survey 1 Survey 2 RATING OF NEAR VISUAL ACUITY (Q7b)

Fig. 6-32. Unit of measure is in a scale where 1 = inability to perform the activity due to visual difficulty and 10 = perfect, no problem.

Treatment group Question 7c. How do you rate your unaided vision in daytime driving?

How do you rate your unaided vision in daytime driving? 70 No applicable, do not drive 65 63 63 Scale of 1 = inability to perform 59 60 the activity due to visual difficulty Scale of 2

50 Scale of 3

40 Scale of 4

% Scale of 5 30 Scale of 6 22 20 18 20 17 Scale of 7

11 10 10 10 8 Scale of 8

Scale of 9 0 1st survey 2nd survey 3rd survey 4th survey Scale of 10 = perfect, no problem N=216 N= 100 N=123 N=123 Fig. 6-33. Overview of responses at all 4 surveys.

188 Figure 6-33 shows that on average 63% of the subjects rated un-aided daytime driving as 10 out of 10, followed by 9 out of 10 (average 19%), then 8 out of 10 (average 10%). A minor percentage of subjects gave lower ratings, in fact only 4% (average in 4 surveys) gave a rating less than or equal to 5 out of 10. The responses were similar in all four surveys.

Control group Question 4c. How do you rate your aided vision in daytime driving?

How do you rate your aided vision in day time driving?

68 70 Scale of 1 = inability to perform the activity due to visual difficulty Scale of 2 60

Scale of 3

50 Scale of 4

40 Scale of 5 % 29 Scale of 6 30

Scale of 7 20 16 13 Scale of 8

8 10 8 Scale of 9

0 Scale of 10 = perfect, no problem 1st survey N=49 2nd survey N=40

Fig. 6-34. Overview of responses in both surveys.

Figure 6-34 shows that on average 49% of the subjects rated aided daytime driving at 10 out of 10, followed by 9 out of 10 (average 15%); then 8 out of 10 (average 8%). Thirty nine percent more subjects gave a rating of 10 out of 10 in survey 2, almost twice as many as in survey 1. This is probably due to the improvement in daytime driving ability brought about by newly prescribed glasses and/or contact lenses.

Comparison between subjects’ ratings of daytime driving in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-35 showed that there was no overall significant difference between the two groups (F 1,141 = 0.65, p = 0.42). There was no change from survey 1 to 2 (F 1,141 = 3.35, p = 0.07) and no interaction (F 1,141 = 2.97, p = 0.09).

189 Comparison of the subjects’ perception of their daytime driving

Ability between the treatment and control group 9.6 Daytime driving at 2 nd survey in control group 9.5

9.4

9.3 Daytime driving at 1 st survey in control group 9.2 Daytime driving at 2 nd survey in treatment group

9.1 Treatment group Estimated Marginal Means Estimated Marginal Daytime driving at 1 st survey in treatment group 9.0 Control group Survey 1 Survey 2

RATING OF DAYTIME DRIVING (Q7c)

Fig. 6-35. Unit of measure is in a scale where 1 = inability to perform the activity due to visual difficulty and 10 = perfect, no problem.

Treatment group Question 7d. How do you rate your unaided vision in night driving?

How do you rate your unaided vision in night driving? 40 No applicable, do not drive

35 Scale of 1 = inability to perform 35 32 the activity due to visual difficulty 30 Scale of 2 30 29 Scale of 3 25 22 Scale of 4 20 20 20 19 19 % 18 17 Scale of 5 16 16 15 15 Scale of 6 12 11 10 Scale of 7

Scale of 8 5 Scale of 9 0 1st survey 2nd survey 3rd survey 4th survey Scale of 10 = perfect, no problem N=216 N= 100 N=123 N=122

Fig. 6-36. Overview of responses at all 4 surveys.

Figure 6-36 shows that on average 32% of the subjects rated their unaided vision in night driving at 10 out of 10, followed by 9 out of 10 (average 20%); 8 out of 10 (average 18%); then 7 out of 10 (average 14%). Fifty percent more subjects rated vision for night driving at 5

190 out of 10 than vision for daytime driving. This suggests that unaided vision for night driving was more problematic for subjects, and the quality of vision was light dependent post-LASIK. Furthermore, out of all four visual tasks in Question 7, unaided vision for near or close work, and vision in night driving, had the lowest ratings. This highlights that quality of vision after LASIK may fall short with regard to fine detail work and when light conditions are not optimal. Further study is needed to quantify such tasks in different lighting conditions pre- and post-operatively to assess what difficulties are pre-existing and what is contributed by the LASIK procedure.

Control group Question 4d. How do you rate your aided vision in night driving?

How do you rate your aided vision in night driving?

58 60 Scale of 1 = inability to perform the activity due to visual difficulty Scale of 2 50 Scale of 3

39 40 Scale of 4

Scale of 5 % 30 Scale of 6

20 Scale of 7

12 13 12 Scale of 8 10 8 10 5 Scale of 9

0 Scale of 10 = perfect, no problem 1st survey N=49 2nd survey N=40

Fig. 6-37. Overview of responses in both surveys.

Figure 6-37 shows that on average 49% of the subjects rated their aided vision in night driving at 10 out of 10, followed by 9 out of 10 (average 10%), then 8 out of 10 (average 13%), and 7 out of 10 (average 12%). Slightly more subjects gave a lower rating compared to daytime driving (Question 4c). This is consistent with the treatment group, suggesting that night driving can also be a problematic aspect for the control group, and that the lower rating in the treatment group could possibly relate to pre-existing factors.

191 Comparison between subjects’ ratings of night driving in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-38 showed no overall significant difference between the two groups (F 1,141 = 1.98, p = 0.16). There was change (F 1,140 = 9.62, p = 0.002), which the interaction (F 1,140 = 8.72, p = 0.004) and graph suggest was mainly due to the control group which improved from survey 1 to 2 probably due to newly prescribed glasses and/or contact lenses.

Comparison of the subjects’ perception of their night driving

Ability between the treatment and control groups 9.0 Night driving at 2 nd survey in control group

8.8

8.6

8.4 Night driving at 1 st survey in control group 8.2 Night driving at 2 nd survey in treatment group

8.0 Treatment group

Estimated MarginalMeans st 7.8 Night driving at 1 survey in treatment group Control group Survey 1 Survey 2

RATING OF NIGHT DRIVING (Q7d)

Fig. 6-38. Unit of measure is in a scale, where 1 = inability to perform the activity due to visual difficulty and 10 = perfect, no problem.

Treatment group Question 8a. Are there any changes in your vision which affected or improved your ability to perform physical activities?

Are there any changes in your vision which affect or improve your ability to perform physical activities? 80 71 70 61 59 60 56

50

% 40 No applicable, physically un-advisable 27 30 25 26 Worse

20 15 15 16 No change 11 13 10 Better

0 Much improved 1st survey 2nd survey 3rd survey 4th survey N=215 N= 100 N=123 N=120

Fig. 6-39. Overview of responses at all 4 surveys.

192 Figure 6-39 shows that on average 62% of the subjects rated their ability to perform physical activities much improved; better (average 24%); and no change (average 14%). On average, only 1% indicated “worse”. More clinical details about these two subjects follow (also see Appendix XXV): One subject lost one line BCVA; enhancement was discussed twice, but the subject elected not to proceed with it. One subject had severe dry eyes by 24 months operatively which caused a loss of seven lines UCVA and three lines BCVA.

Control group Question 5a. Think back to the time your last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform physical activities?

Think back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform physical activities? 80 75 65 70 No applicable, physically un-advisable 60 Much worse 50 Worse % 40 30 23 No change 20 10 Better 6 10 2 Much improved 0 1st survey N=48 2nd survey N= 40

Fig. 6-40. Overview of responses in both surveys.

Figure 6-40 shows that on average 57% of the subjects considered their ability to perform physical activities had not changed since the previous eye examination; 15% thought it was better; 6% much improved. Fifteen percent felt it was worse at the first survey, but with their newly prescribed glasses and/or contact lenses the rating improved at the second survey. More subjects in the treatment group rated their ability to perform physical activities as better or much improved consistently in all four surveys, and as further illustrated by the ANOVA analysis below, this indicates that the LASIK procedure provided more prominent improvement than glasses and/or contact lenses.

193 Comparison between subjects’ ratings of physical activities in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-14 showed that there was a significant difference between the two groups, in that the treatment group had a higher mean rating score than the control group (F 1,140 = 52.15, p < 0.001). There was change (F 1,140 = 18.55, p <

0.001), which the interaction (F 1,140 = 15.59, p < 0.001) and graph suggest was mainly due to the control group which improved from survey 1 to 2 probably due to the newly prescribed glasses and/or contact lenses.

Comparison of the subjects’ perception in their ability to perform

physical activities between treatment & control groups 4.5 Physical activities at 2 nd survey in treatment group

st

Physical activities at 1 survey in treatment group 4.0 Physical activities at 2 nd survey in control group

3.5

3.0 Treatment group Physical activities at 1 st survey in contro l group 2.5 Control group Estimated MarginalMeans Survey 1 Survey 2

RATING OF ABILITY TO PERFORM PHYSICAL ACTIVITIES (Q8a)

Fig. 6-41. Unit of measure is in a scale where 1 = much worse and 5 = much improved.

Treatment group Question 8b. Are there any changes in your vision which have affected or improved your ability to perform social or recreational activities?

Are there any changes in your vision which affect or improve your ability to perform social or recreactional activities? 68 70 63 58 60 54

50

40 % 32 No applicable, 30 27 physically un-advisable Worse 20 21 20 13 13 14 No change 10 10 Better

0 Much improved 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=122

Fig. 6-42. Overview of responses at all 4 surveys.

194 Figure 6-42 shows that on average 61% of the subjects rated their ability to perform social or recreational activities as much improved; 25% rated it better (average 25%); and 13% reported no change. On average, only 1% rated this as worse. Clinical details about these subjects follow (see Appendix XXVI): Two subjects could not adapt to monovision; one was the same subject mentioned in question 8a who lost one line BCVA and elected not to have enhancement.

Control group Question 5b. Thinking back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform social or recreational activities?

Think back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform social/recreational activities?

90 81 80 68 No applicable, 70 physically un-advisable Much worse 60

50 Worse % 40 No change 30 18 20 13 Better 4 4 10 Much improved 0 1st survey N=47 2nd survey N= 40

Fig. 6-43. Overview of responses in both surveys.

Figure 6-43 shows that on average 75% of the subjects rated no change in their ability to perform social or recreational activities; 11% rated it better, and 9% much improved. Eleven percent of the subjects felt that it was much worse at the first survey, but with their newly prescribed glasses and/or contact lenses the rating improved at the second survey. More subjects in the treatment group rated their ability to perform social or recreational activities as better and much improved consistently in all four surveys. As further illustrated by the ANOVA analysis below, the LASIK procedure provided more prominent improvement than glasses and/or contact lenses.

195 Comparison between subjects’ ratings of social/recreational activities in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-44 showed a significant difference between the two groups such that the treatment group had a higher mean score in rating of their ability to perform social/recreational activities (F 1,140 = 43.68, p < 0.001). There was change (F 1,140 =

15.02, p < 0.001), which the interaction (F 1,140 = 13.20, p < 0.001) and graph suggest was mainly due to the control group which improved from survey 1 to 2 probably due to the newly prescribed glasses and/or contact lenses.

Comparison of the subjects’ perception in their ability to perform social / recreational activities between treatment & control group 4.6 Social/recreational activities at 1 st survey in treatment group 4.4 4.2 Social/recreational activities at 2 nd survey in treatment group

4.0 3.8 Social/recreational activities at 1 st survey in control group 3.6 3.4 3.2 Treatment group 3.0 Social/recreational activities at 1 st survey in control group 2.8 Control group Estimated Marginal Means Estimated Marginal Survey 1 Survey 2

RATING OF THE ABILITY TO PERFORM SOCIAL/RECREATIONAL ACTIVITIES (Q8b)

Fig. 6-44. Unit of measure is in a scale where 1 = much worse and 5 = much improved.

Treatment group Question 8c. Are there any changes in your vision which have affected or improved your ability to perform home activities?

Are there any changes in your vision which affect or improve your ability to perform home activities? 70 62 60 51 49 48 50

40 % 30 No applicable, 28 physically un-advisable 30 27 25 Worse 22 20 20 19 No change 11 10 Better

0 Much improved 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=120 Fig. 6-45. Overview of responses at all 4 surveys.

196 Figure 6-45 shows that on average 52% of the subjects rated their ability to perform home activities as much improved; 28% rated it better (average 28%); and 18% reported no change. On average, only 2% rated it worse. Clinical details about these subjects follow (see also Appendix XXVII): Two subjects could not adapt to monovision and had some deterioration of visual acuity: one was the same subject mentioned in Question 8a & b, who elected not to have enhancement. The other had severe dry eyes, as mentioned earlier, and had lost visual acuity from 6/6 pre- operative BCVA to 6/20 post-operative UCVA.

Control group Question 5c. Thinking back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected/improved your ability to perform home activities?

Think back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform home activities?

70 63 58 60 No applicable, physically un-advisable 50 Much worse

40 Worse % 30 30 23 No change 20 10 Better 8 6 10 3 0 0 0 0 Much improved 0 1st survey N=48 2nd survey N= 40

Fig. 6-46. Overview of responses in both surveys.

Figure 6-46 shows that on average 61% of the subjects rated no change in their ability to perform home activities; 19% rated it better, and 8% rated it much improved. Twenty three percent of subjects felt it was worse at the first survey, but with the newly prescribed glasses and/or contact lenses the ratings improved at the second survey. More subjects in the treatment group rated their ability to perform home activities as better to much improved in all four surveys, which, as further illustrated by the ANOVA analysis below, indicates that the LASIK procedure provided more prominent improvement than glasses and/or contact lenses.

197 Comparison between subjects’ ratings of home activities in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-47 showed a significant difference between the two groups in that the treatment group had a higher mean score than the control group

(F 1,141 = 30.57, p < 0.001). There was change (F 1,141 = 16.84, p < 0.001), which the interaction

(F 1,141 = 11.78, p = 0.001) and graph suggest was mainly due to the control group which improved from survey 1 to 2 probably due to the newly prescribed glasses and/or contact lenses.

Comparison of the subjects’ perception in their ability to perform

home activities between treatment and control groups Home activities4.4 at 1 st survey in treatment group 4.2 nd Home activities at 2 survey in treatment group 4.0

3.8 Home activities at 2 nd survey in control group 3.6 3.4 3.2 3.0 Treatment group Home activities at 1 st survey in control group 2.8 Control group

Estimated MarginalMeans Survey 1 Survey 2

RATING OF ABILITY TO P ERFORM HOME ACTIVITIES (Q 8c)

Fig. 6-47. Unit of measure is in a scale where 1 = much worse and 5 = much improved.

Treatment group Question 8d. Are there any changes in your vision which have affected or improved your ability to perform work activities?

Are there any changes in your vision which affect or improve your ability to perform work activities? 70 62 60 51 49 48 50

40 % 30 No applicable, 28 physically un-advisable 30 27 25 Worse 22 20 20 19 No change 11 10 Better

0 Much improved 1st survey 2nd survey 3rd survey 4th survey N=212 N= 98 N=122 N=119

Fig. 6-48. Overview of responses at all 4 surveys.

198 Figure 6-48 shows that on average 50% of the subjects rated their ability to perform work activities as much improved; 25% rated it better, and 20% reported no change. On average, 5% rated it worse. Of the four activities addressed in Question 8, work and home activities had more lower ratings, suggesting that perhaps these tasks required more refined vision, and that the quality of vision post-LASIK was not refined enough for these activities. More clinical details about subjects who gave “worse” ratings follows (see also Appendix XXVIII): There were 12 subjects: four could not adapt to monovision; four were presbyopes who elected to have bilateral emmetropic correction and had difficulty with near vision and with the computer; five had some deterioration of visual acuity; one was the same subject mentioned in Question 8a & b who had lost five lines of BCVA; one had marked loss of BCVA and UCVA, and was wearing hard contact lenses with -6.25D and -5.75D right and left respectively while waiting to have customized enhancement; finally, one subject had severe dry eyes, the same patient mentioned in Questions 8a & c with marked deterioration of visual acuity.

Control group Question 5d. Thinking back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform work activities?

Think back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform work activities? 58 60 54

50 No applicable, physically un-advisable Much worse 40 31 28 Worse % 30 No change 20 13 8 Better 10 6 3 0 0 0 0 Much improved 0 1st survey N=48 2nd survey N= 40

Fig. 6-49. Overview of responses in both surveys.

199 Figure 6-49 shows that on average 56% of the subjects reported no change in their ability to perform work activities; 18% rated it better, and 10% rated it much improved. Thirty two percent of subjects felt that it was worse at the first survey, but with their newly prescribed glasses and/or contact lenses the rating improved at the second survey. More subjects in the treatment group rated their ability to perform work activities as better to much improved in all four surveys which, as further illustrated by the ANOVA analysis below, indicates that the LASIK procedure provided more prominent improvement than glasses and/or contact lenses.

Comparison between subjects’ ratings of work activities in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-50 showed a significant difference between the two groups in that the treatment group had a higher means score than the control group

(F 1,138 = 21.83, p <0.001). There was change (F 1,138 = 16.05, p < 0.001), which the interaction

(F 1,138 = 16.90, p = 0.001) and graph suggest was mainly due to the control group which improved from survey 1 to 2 probably due to the newly prescribed glasses and/or contact lenses.

Comparison of the subjects’ perception in their ability to perform work

activities between the treatment and control group 4.2 Work activities at 1 st survey in treatment group

4.0 Work activities at 2 nd survey in treatment group

3.8

3.6 Home activities at 2 nd survey in control group 3.4

3.2

3.0 Treatment group

Estimated MarginalMeans st 2.8 Home activities at 1 survey in control group Control group Survey 1 Survey 2

RATING OF ABILITY TO PERFORM WORK ACTIVITIES (Q 8d)

Fig. 6-50. Unit of measure is in a scale where 1 = much worse and 5 = much improved.

200 Treatment group Question 9. Do you need to wear glasses and/or contact lenses now? If yes, for what purpose? This question is relevant to the treatment group only, thus, no comparison is provided.

Do you need to wear glasses and/or contact lenses now? If yes, for what purpose?

80 76 70 75 73 70 60 50 No % 40 Not yet, but straining Yes, for distance & 30 25 night driving 19 20 19 Yes, for near vision 20 Yes, for distance & 10 near vision 3 4 3 2 4 3 Yes, for dim light and 0 0 low contrast condition 0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=122 N=123

Fig. 6-51. Overview of responses at all 4 surveys.

Figure 6-51 shows that on average 74% of the subjects no longer required glasses and/or contact lenses, and 21% wore glasses for near vision. This reflects the percentage of presbyopic subjects who elected to have bilateral emmetropic correction and were expected to wear reading glasses post-operatively (see Appendix V). A minor percentage of subjects (average 5%) still needed to wear glasses for distance and night driving and for dim light and low contrast conditions. This reflects the percentage of subjects who reported difficulty in a number of visual tasks in Questions 7 and 8, as well as subjects who could not adapt to monovision. More clinical details regarding subjects who required glasses and/or contact lenses post-operatively follow: (see also Appendices XXIX, XXX and XXXI): Six subjects needed glasses for distance and/or night driving: three could not adapt to monovision; one had dry eyes (the same subject mentioned earlier in Questions 8a & c; three were high myopes pre-operatively, two of these had lost lines of BCVA and one had requested enhancement but corneal pachymetry was too thin to do so. Among those who needed glasses for near or close work, almost 50% were over the age of 40 and elected to have bilateral emmetropic correction knowing that they would have presbyopic symptoms. The final group

201 were the presbyopes who elected to have monovision correction, about 30% of whom required glasses for near or close work, which suggests that the monovision treatment had not worked as well as predicted or they could not adapt to it.

Treatment group Question 10. If any, what is the ONE MAIN symptom that you are experiencing?

If any, what is the ONE MAIN symptom that you are experiencing? 40 40 39 36 No No symptom, but pure 35 33 pleasure Blur at distance 30 Blur at near & mid distance 25 25 Blur at near & distance Blur compare to other eye 20 20 18 % 20 Fluctuation of vision Poor night/dim light vision 15 12 Reduced contrast compare 9 9 9 to pre-op. 8 Night glare & glare in 10 7 7 6 7 5 5 5 5 6 6 general 4 Haloes & ghosting 4 4 3 5 3 Head aches 0 Dry, irritation & red eyes 1st survey 2nd survey 3rd survey 4th survey Tired & epiphoric N=201 N= 93 N=113 N=118 Others

Fig. 6-52. Overview of responses at all 4 surveys.

Figure 6-52 shows that on average 39% of the subjects did not nominate a symptom; an average of 21% of subjects complained of dry, irritated and red eyes; and 20% nominated blurring in near and middle distance vision. These were the presbyopic or near presbyopic subjects who had emmetropic correction. The other minor percentages were distributed among symptoms such as glare in general (average 8%), and poor vision at night or in dim light conditions, blurring in one eye when compared between eyes (each average 6%). An interesting point to note is that, the percentage of “less clear in one eye” reduced by half from the first two surveys to the third and fourth survey. This finding suggests that by 12 and 24 months post-operatively subjects may have adapted to the difference in clarity between the two eyes and no longer consider it a symptom, or else the differences in clarity had improved.

202 Lastly, 2% (on average) of the subjects complained of haloes, fluctuation of vision, tired eyes and epiphoric headaches, blur at near and distance vision, and reduced contrast.

Control group Question 3. If any, what is the ONE MAIN SYMPTOM or ANNOYANCE that you are experiencing?

If any, what is the ONE MAIN SYMPTOM or ANNOYANCE that you are experiencing?

No 45 43 Blur at near 40 38 Dusty, dirty & sweaty lenses 35 Problem with fitting of glasses 30 M/F restricted head & eyes movement 25 Have to wear glasses & misplaced them % Glare 20 17 18 Head aches 15 13 10 Poor & fluctuation of vision 10 8 8 6 6 5 Haloes at night 4 5 2 3 Dry, irritation & tired eyes 0 Epiphoric 1st survey N=48 2nd survey N= 40 Restricted peripheral vision

Fig. 6-53. Overview of responses in both surveys.

Figure 6-53 shows that on average 41% of the subjects did not nominate a symptom. An average of 18% nominated dry, irritated and tired eyes, 12 % a problem with fitting of glasses, 7% complained of having to wear glasses and misplacing them. An average of 5% (each) of subjects nominated dusty, dirty and sweaty lenses, blur for near vision, and glare. The other minor percentages were distributed among symptoms such as glare, headaches, and haloes at night. As stated earlier, of the 49 control subjects 38 of them had new glasses and/or contact lenses prescribed at the end of survey 1 as part of their annual refraction up-date. Many of the symptoms were comparable with those reported by the treatment group, except that symptoms such as varying in vision at different distances, between eyes, poorer night vision and reduced contrast sensitivity were associated with the treatment group only. Symptoms such as dusty, dirty, sweaty lenses, problems with glasses fitting, having to wear glasses, and misplacing them were associated with the control group only. The symptoms common to both groups

203 were dry and irritable eyes, glare, and haloes at night, suggesting that part of these symptoms could be pre-existing factors for the LASIK subjects.

Treatment group Question 11. In your opinion has the surgery had any effect on your overall quality of life?

In your opinion has the surgery had any effect on your overall quality of life? 70 70 65 62 60 56

50

40 37 % 33 29 Much w orse 30 24 Worse 20 No different 10 5 5 6 5 Better

0 Much improved 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123

Fig. 6-54. Overview of responses at all 4 surveys.

Figure 6-54 shows that on average 63% of the subjects rated the effect on their quality of life as much improved; 31% rated it better, and 5% reported no change. Only 1% rated it worse, it consists of one subject, mentioned earlier in Questions 7, 8, and 10 with 3 lines lost of BCVA, by 24 months post-operatively had UCVA of 6/24 compared to 6/6 pre-operatively. This subject had severe dry eyes and fluctuation of visual acuity since the procedure. A second subject, mentioned in Questions 8 and 9, could not adapt to monovision, and a third subject, mentioned in Question 8, had severe decentred ablation and was waiting for customized enhancement.

204 Control group Question 6. Thinking back to the time you last had your eyes examined (about 6 months ago), what effect has wearing glasses and/or contact lenses since then had on your overall quality of life?

Think back to the time you last had your eyes examined (about 6 months ago), what effect has wearing glasses and/or contact lenses since then had on your overall quality of life? 70 70

60

50 45 38 40 Much w orse % 30 Worse

18 No different 20 15 11 Better 10 Much improved 0 1st survey N=47 2nd survey N= 40

Fig. 6-55. Overview of responses in both surveys.

Figure 6-55 shows that on average 58% of the subjects rated the effect on their quality of life as no change; 20% rated their quality of life as better, and 15% as much improved. More than 20% of the subjects’ ratings improved at the second survey. More subjects in the treatment group rated their quality of life as better to much improved in all four surveys which, as further illustrated by the ANOVA analysis below, indicates that the LASIK procedure provided more prominent improvement than glasses and/or contact lenses.

Comparison between subjects’ ratings of overall quality of life in the treatment and control groups at first and second surveys: A 2(group) x 2(time) ANOVA analysis in figure 6-56 showed a significant difference between the two groups in that the treatment group had a higher mean rating score than the control group (F 1,140 = 64.03, p < 0.001). There was change (F 1,140 = 6.14, p = 0.01), which the interaction (F 1,140 = 11.52, p = 0.001) and graph suggest was mainly due to the control group which improved from survey 1 to 2 probably due to the newly prescribed glasses and/or contact lenses.

205 Comparison of the mean rating scores in overall quality of life between the treatment and control group 4.6 Quality of life at 2 nd survey in treatment group

4.4 st Quality of life at 1 survey in treatment group 4.2

4.0

nd 3.8 Quality of life at 2 survey in control group

3.6

3.4 Treatment group

Estimated Marginal Means Estimated Marginal st 3.2 Quality of life at 1 survey in control group Control group Survey 1 Survey 2

RATING OF OVERALL QUALITY OF LIFE (Q 11)

Fig. 6-56. Unit of measure is in a scale where 1 = much worse and 5 = much improved.

The third and fourth section (part I) of the questionnaire consisted of seven questions which were relevant to the treatment group only. These questions addressed the amount of information given to the subjects before, during and after the procedure, and whether they fully understood the information. Three questions assess rating of the surgery, and whether the surgery outcomes meet their pre-operative expectations. They are as follows: Treatment group Question 12a. Was enough information given to you about LASIK prior to the surgery?

Was enough information given to you about LASIK prior to the surgery?

80 70 69 70 70 67

60

50

% 40 Almost nothing 30 22 22 22 Not enough 19 20 Satisfactory 10 8 9 10 7 Good

0 Excellent 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123

Fig. 6-57. Overview of responses at all 4 surveys.

206 Figure 6-57 shows that on average 69% of the subjects rated the amount of information given prior to surgery as excellent; 21% rated it as good, and 8% rated it satisfactory (average 8%). On average, 2% of the subjects responded that they had not received enough information. Question 12b captured that these subjects considered they had not received enough information about monovision and its effect, and glare.

Treatment group Question 13a. Was enough information given to you as what to expect immediately after the surgery (i.e., pain, glare, blur)?

Was enough information given to you about what to expect immediately after the surgery? (i.e. pain, glare, blur) 70 64 63 62 61 60

50

40

% Almost nothing 30 23 24 24 20 Not enough 20 Satisfactory 9 11 10 10 9 Good

0 Excellent 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123 Fig. 6-58. Overview of responses at all 4 surveys.

Figure 6-58 shows that on average 62% of the subjects rated the amount of information about what to expect immediately after the procedure as excellent, 22% rated it as good, and 10% as satisfactory. On average, 6% of the subjects reported that there was not enough information about epithelium defect and poor night vision post-operatively.

Treatment group Question 14a. How much information were you given regarding the regime of using eye drops, and medication?

How much information were you given regarding the regime of using eye drops, and medication? 98 100 95 95 93 90

80

70

60 % 50 None 40

30 Some 20 5 5 6 10 0 0 0 2 1 Complete 0 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123 Fig. 6-59. Overview of responses at all 4 surveys.

207 Figure 6-59 shows that on average 95% of the subjects considered that they had been given complete information, and 5% reported some information. Only one subject reported no information given. This subject did not elaborate, but responded positively to the rest of the questionnaire, which might suggest that the subject had misread the question.

Treatment group Question 15. How would you rate the success of the surgery?

How would you rate the success of the surgery?

90 82 79 81 80 72 70

60

50 % Very unsuccessful 40 Moderately 30 24 unsuccessful 19 Moderatelysuccessful 20 15 12 More than moderately 10 4 3 successful 2 2 1 2 1 0 Very successful 0 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123 Fig. 6-60. Overview of responses at all 4 surveys.

Figure 6-60 shows that on average 79% of the subjects rated the surgery very successful, 18% rated it moderately successful, 3% rated it more than moderately successful, 2% rated it moderately unsuccessful, and 1% rated it very unsuccessful. Clinical details regarding the subjects in the latter thee groups follow (see also Appendix XXXII): There were four subjects: two could not adaptable to monovision, the same subjects mentioned in Questions 8, 9, and 11. One had lost lines of BCVA and elected not to have enhancement, the same subject mentioned in Question 8. One had severe loss of lines of BCVA and UCVA due to decentred ablation. This subject was waiting for customized enhancement, as mentioned in Questions 8.

208 Treatment group Question 16. How do you compare your satisfaction now with your pre- operative expectations?

How do you compare your satisfaction now with your pre-operative expectations? 45 43 39 40 38 35 35 29 30 28 26 27 24 24 25 21 23 % Surgery outcomes 20 partially met expectation 15 Surgery outcomes met 15 expectation 10 11 10 8 Surgery outcomes slightly exceeded 5 expectations Surgery outcomes 0 greatly exceeded expectations 1st survey 2nd survey 3rd survey 4th survey N=215 N= 101 N=123 N=123

Fig. 6-61. Overview of responses at all 4 surveys.

Figure 6-61 shows that on average 39% of subjects considered that the surgery outcome met their expectations; for 26% the surgery outcome greatly exceeded their expectations; for 25% the surgery outcome slightly exceeded their expectations; and for 11% the surgery outcome partially met their expectations. These latter subjects also expressed dissatisfaction elsewhere in the questionnaire. Clinical details regarding these subjects follow (see also Appendix XXXIII): Twelve subjects had monovision correction – two of these had enhancement to remove monovision, one had discussed enhancement but did not proceed, nine could not adapt to monovision, and two had loss of UCVA and BCVA. Eight subjects had bilateral emmetropic correction – three of these were high myopes and three were hyperopes pre-operatively. Three of them had residual refractive errors, two had residual refractive error with presbyopic symptoms, one had dry eyes, one had night driving difficulty, one had a flap clean and refloat and diffuse lamellar keratitis and lost lines of BCVA. One had decentred ablation and was wearing hard contact lenses while waiting for customized enhancement. Two had dry eyes and lost lines of BCVA. Lastly, one patient had unilateral treatment as the fellow eye had a history of iritis, but the subject might have had higher expectations.

209 Treatment group Question 17. Now that you have undergone the surgery, knowing what you know now, would you still have LASIK?

Now that you have undergone the surgery, knowing what you know now, would you still have LASIK? 100 95 94 96 97 90

80

70

60

50 % Yes 40 Probably 30 Undecided 20 10 4 Questionable 1 1 3 1 1 1 0 2 2 0 0 0 2 2 0 0 No 1st survey 2nd survey 3rd survey 4th survey N=215 N= 100 N=123 N=123

Fig. 6-62. Overview of responses at all 4 surveys.

Figure 6-62 shows that on average 95% of the subjects stated they would have the LASIK procedure again, while 3% marked “questionable”, and 1% each gave responses of probably, undecided and no. More clinical details regarding these subjects follow (see also Appendix XXXIV): Five subjects indicated “undecided”: three could not adapt to monovision, one had dry eyes and had lost some UCVA and BCVA, and one had a flap clean and refloat immediately post- operatively and as a result was less satisfied with the procedure. One subject indicated “no” because of inability to adapt to monovision, also responding negatively throughout Questions 8, 9, and 11 in the questionnaire. Four subjects indicated “questionable”: one could not adapt to monovision, one had dry eyes and marked loss of UCVA and BCVA as reported in Question 8, one had bilateral decentred ablation and was wearing hard contact lenses while waiting for customized enhancement. Lastly, one was a moderate myope pre-operatively and had an enhancement.

210 Treatment group Question 18. Would you have the second eye done if required?

Would you have the second eye done if required? 96 98 98 98 70

60

50 Yes

40 Probably % 30 With a lot of consideration

Probably not 20 Undecided 10 2 Not applicable (do not 1 1 0 0 0 0 1 1 0 0 1 0 required or unsuitable 1st survey 2nd survey 3rd survey 4th survey N=212 N= 100 N=122 N=122

Fig. 6-63. Overview of responses at all 4 surveys.

Figure 6-63 shows that on average 98% of the subjects responded that they would the second eye done. It is worth mentioning that all the subjects in this study in fact had simultaneous bilateral LASIK. The answers to this question are retrospective, giving subjects another opportunity to state dissatisfaction if any. Thus only 2% of the subjects indicated some degree of uncertainty. Details regarding these subjects follow; they have already been mentioned due their negative responses to earlier questions: Scales rating Comments “Probably not” Subject 58 as mentioned in Questions 8, 9, 11, 15, 16 and 17, unable to adapt to (2) monovision Subject 77 as mentioned in Question 16, had B/L -10.0D correction, had DLK, lost 3 lines BCVA, complained of glare and dry eyes Subject 152 had bilateral -9 & -8D correction, no lost BCVA, patient may has misread the question, this was confirmed in later surveys and by no other negative responses. “With a lot of Subject 53 as mentioned in Question 8, had (R) enhancement, lost 2 lines BCVA, had consideration” problem with reading and computer. (3) “Undecided” Subject 9 as mentioned in Question 16, had (R) monovision (L) emmetropic correction (4) could read N4.5 & 6/6 UCVA post-op, only completed first survey, complained of sore eyes at night. Subject 210 had B/L emmetropic correction, no negative responses in all surveys except for minor dry eyes and blepharitis, required readers, patient was presbyopic.

211 In the fourth section, part 2 consisted of two questions which were comparable across both the treatment and control groups with minor different in wording, assessing whether subjects would recommend the treatment and how satisfied they were. Research question 15*: From a treatment satisfaction perspective, would subjects recommend one form of treatment over the other when compared between the treatment and control groups? (Note, this is a central research question) Treatment group Question 19. Would you recommend LASIK to someone else?

Would you recommend LASIK to someone else? 96 95 98 97 70

60

50

40 Yes % Depend on the eye 30 condition & reason Probably 20 Undecided 10 3 3 2 2 2 1 1 0 0 0 0 1 0 1st survey 2nd survey 3rd survey 4th survey N=215 N= 100 N=123 N=123 Fig. 6-64. Overview of responses at all 4 surveys.

Figure 6-64 shows that on average 96% of the subjects responded that they would recommend LASIK, 2.7% said it would depend on the eye condition and reason, 0.5% responded “probably”. Only 1% responded “undecided” because of inability to adapt to monovision.

Control group Question 9. Would you recommend glasses and/or contact lenses to someone else?

Would you recommend glassses and/or contact lenses to some-one else? 86 83 70

60

50 Yes 40 Depend on the eye % condition & reason 30 Undecided

20 No 10 4 6 5 10 4 3

0 1st survey N=48 2nd survey N=40

Fig. 6-65. Overview of responses in both surveys.

212 Figure 6-65 shows that on average 85% of the subjects would recommend glasses and/or contact lenses, 8% responded “no”, 5% considered it would depend on the eye condition and reason, and 4% were undecided. Among those who would not recommend glasses and/or contact lenses, one subject in fact recommended laser surgery. There were 10% more subjects recommend LASIK, this is further illustrated by the Chi-square analysis below.

Comparison of subjects’ recommendations between the treatment and control groups at first and second surveys: Table 6-12. 2X2 factorial analysis of subjects’ recommendations between treatment and control groups Recommend Not recommend Statistical outcomes p < 0.05 Survey 1 Control N = 38 N = 14 Corrected chi-square = 16.92 group p < 0.001 (significant, in that LASIK N = 207 N = 16 LASIK patients would more group readily recommend the procedure) Survey 2 Control N = 35 N = 12 Corrected chi-square = 7.70 group p = 0.006 (significant, in that LASIK N = 95 N = 9 LASIK patients would more group readily recommend the procedure)

Table 6-12 shows significant differences, in that the treatment group subjects would more readily recommend the LASIK procedure compared to willingness of the control group subjects to recommend glasses and/or contact lenses.

Research question 16*: Again, from a treatment satisfaction perspective, how do the satisfied and dissatisfied subjects compare between the treatment and control groups? (Note, this is a central research question) Treatment group Question 20. Are you more satisfied or less satisfied with the vision you have now compared to the vision you had previously with glasses and/or contact lenses?

213 Are you more satisfied or less satisfied with the vision you have now compared to the vision you had previously with glasses and/or contact lenses?

70 66

60 57 57

50 48 Much more satisfied

40 Some w hat more % satisfied 30 About the same 24 21 22 23 Undecided 20 18 16 13 13 Some w hat les satisfied 10 6 3 4 2 2 2 Less satisfied 1 1 1 0 2 1 0 1st survey 2nd survey 3rd survey 4th survey N=216 N= 101 N=123 N=123

Fig. 6-66. Overview of responses at all 4 surveys. Unit of measure is in scale, where 1 = less satisfied, 2 = somewhat less satisfied, 3 = about the same, 4 = somewhat more satisfied, and 5 = much more satisfied.

Figure 6-66 shows that on average 56.8% of the subjects rated themselves as much more satisfied, 19.6% as somewhat more satisfied, 17.7% as about the same, 3.7% as somewhat less satisfied, and 1.7% as less satisfied. Less than 1% (on average) of the subjects were undecided. From a surgical and long-term perspective, the fact that there were slightly more satisfied subjects at the fourth survey provides an excellent insight about the procedure. More detail regarding the dissatisfied/less satisfied subjects is provided below. Again these subjects have been mentioned earlier due to their negative responses to other questions (see also Appendix XXXV): Six subjects could not adapt to monovision. Nine subjects had various degrees of lost lines UCVA and BCVA: two of these had decentred ablation, one was wearing hard contact lenses while waiting for customized enhancement, three had dry eyes, one had dry eyes and fine wrinkles on the flap. Finally, three subjects had poor night vision. It was speculated earlier that subjects with unintended surgical outcomes might be less satisfied. On the contrary, when subjects with unintended surgical outcomes were examined individually, not one of them expressed dissatisfaction (see Appendix XXXVI for their satisfaction scores).

214 Commonly in patient satisfaction study such as this, a neutral point is usually included on a scale, in this case “about the same”, to avoid the acquiescence affect. It is also a common problem to interpret what exactly is the subject is thinking and whether subjects were really satisfied or really dissatisfied. In order to increase understanding, closer examination was undertaken of the responses of individual subjects who used the “about the same” rating. They ranged from 20 to 69 years of age, average of four surveys the median is 39 years, gave similar ratings for their unaided distance and near vision, some still required and some no longer required glasses and/or contact lenses post-operatively. There was no specific pattern of responses to the rest of the questionnaire.

Control group Question 7. How happy are you that you need to wear glasses and/or contact lenses to achieve normal vision?

How happy are you that you need to wear glasses and/or contact lenses to achieved normal vision? 39 38 40 35 35 28 30 23 25 22 Very dissatisfied % 20 Moderately dissatisfied 13 Moderately satisfied 15 Very satisfied 10 4 5

0 1st survey N=49 2nd survey N=40

Fig. 6-67. Overview of responses in both surveys. Unit of measure is in scale, where 1 = very dissatisfied, 2 = moderately dissatisfied, 3 = about the same, 4 = moderately satisfied, and 5 = very satisfied.

Figure 6-67 shows that on average 39% of the subjects rated themselves moderately dissatisfied, 29% as very satisfied, 25% as moderately satisfied, and 9% were very dissatisfied that they needed to wear glasses and/or contact lenses to achieve normal vision.

Comparison of patient satisfaction between the treatment and control groups: With the recoded subjects’ satisfaction scores as described in chapter 5, research question 16, page 142. The cross-tab 2X2 factorial analysis shows:

215 Table 6 -13. 2X2 factorial analysis of subjects’ satisfaction between treatment and control groups Satisfied Dissatisfied Statistics outcomes p < 0.05 Survey 1 Control N = 20 N = 20 Corrected chi-square = 12.0 group p = 0.0005, thus, significant, such LASIK N = 168 N = 48 that LASIK patients were more group satisfied) Survey 2 Control N = 20 N = 20 Corrected chi-square = 3.80 group p = 0.05, thus, significant, such that LASIK N = 70 N = 31 LASIK patients were more group satisfied))

The table 6-13 shows significant differences, in that the LASIK subjects were more satisfied with their treatment compared to the control group subjects with their glasses and/or contact lenses.

Research question 17*: From a stability perspective, are there any significant changes in subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment) over time? (Note, this is a central research question) The following table shows t-test analyses of changes across surveys. Table 6-14. t-test analyses of significant changes in subjects’ responses over time. p < 0.01 Question Survey 1 vs. Survey 2 vs. Survey 3 vs. Survey 2 Survey 3 Survey 4 Experience of pain t = .56, p = .57 t = -.26, p = .80 t = -1.35, p = .18 Experience of irritation t = .71, p = .48 t = 1.31, p = .20 t = -1.0, p = .32 Experience of glare t = 2.60, p = .01 t = 0, p = 1.0 t = -1.03, p = .31

M1 = 1.06

M2 = .88 Experience of dry eye t = -.34, p = .73 t = 1.75, p = .09 t = -0.55, p = .58 Rating of unaided distance vision t = -1.44, p = .15 t = 1.87, p = .07 t = -1.31, p = .20 Rating of unaided near vision t = -.43, p = .67 t = 0.72, p = .47 t = .17, p = .87

216 Question Survey 1 vs. Survey 2 vs. Survey 3 vs. Survey 2 Survey 3 Survey 4 Ability to perform daytime driving t = -.16, p = .88 t = 1.07, p = .29 t = -1.05, p = .30 Ability to perform night driving t = -.26, p = .79 t = -.36, p = .72 t = .76, p = .45 LASIK changes physical activities t = -.73, p = .47 t = -.57, p = .57 t = .31, p = .75 LASIK changes social/recreational t = -.63, p = .53 t = 0, p = 1.0 t = 1.24, p = .22 activities LASIK improves home activities t = -1.0, p = .32 t = .2, p = .84 t = 2.38, p = .02 LASIK improves work activities t = .13, p = .90 t = 0, p = 1.0 t = 3.10, p =.003

M3 = 4.40

M4 = 4.11 LASIK improves overall quality t = 1.04, p = .30 t = -.57, p = .57 t = -1.1, p = .28 of life Information about LASIK given prior t = 0, p = 1.0 t = -.44, p = .66 t = .42, p = .67 to surgery Information given about what to expect t = 1.68, p = .10 t = -1.0, p = .32 t = -.54, p = .59 immediately after the surgery Information given about the regime of eye t = 1.0, p = .32 t = 1.0, p = .32 t = .82, p = .42 drops and tablets after the surgery Rating of surgery success t = 1.28, p = .20 t = .42, p = .68 t = -.59, p = .56 Surgery outcomes relative to pre- t = .20, p = .84 t = -.65, p = .52 t = -.70, p = .49 operative expectations Satisfaction with the vision now compared to t = .89, p = .37 t = -1.04, p = .31 t = -.77, p = .45 previous vision with glasses/contact lenses

Note: M1, 2, 3 and 4 is the mean value at survey 1, 2, 3 and 4

Table 6-14 shows that there were significant changes in only two variables. The first relates to problems with glare, in that subjects reported more glare at survey 1, which is consistent with earlier finding as clinically survey 1 is considered to be the end of stage one in the healing process, and it is not uncommon to find some subjects still complaining of glare. The other variable was subjects’ ability to perform work activities at survey 3, in that subjects felt there was more improvement in their ability to perform work activities at survey 3. This is a positive insight about the procedure from a long-term perspective, as no variables evidenced

217 significantly poorer responses over time. The relationship to subjects’ satisfaction is statistically assessed in subsequent questions.

Research question 18: Repeated measures study is known to have different response rates at each survey. Thus, is there any significant difference in the subjects’ responses to the questionnaire between subjects who returned more than one survey and those who returned for only one survey? The independent samples t-test analysis showed that there was no significant difference between the subjects in the treatment group, who returned more than one survey and those who returned for only one survey for any of the 19 variables in the questionnaire at survey 1 (see Appendix XXXVII).

6.3 Relationships Between Clinical and Subjective/Patient Satisfaction Variables for the treatment group Research question 19*: Is there any correlation between the uncorrected distance and near visual acuity achieved post-operatively and subjects’ satisfaction (score in survey question 20)? (Note, this is a central research question) A bivariate Spearman’s rank-order correlation analysis was conducted. Table 6-15. Bivariate Spearman’s rank-order correlation analysis of subjects’ post- operative visual acuity and their satisfaction (p < 0.01). Post-op distance uncorrected visual Post-op near uncorrected visual acuity (emmetropic group) acuity (monovision group) Q20 score N = 188, r = .10 N = 19, r = .60 survey 1 p = .16 p = .006 Q20 score N = 85, r = -.02 N = 9, r = .60 survey 2 p = .90 p = .09 Q20 score N = 99, r = .04 N = 9, r = .09 survey 3 p = .72 p = .83 Q20 score N = 75, r = .34 N = 8, r = .02 survey 4 p = .003 p = .96 Note: Q20 asked, “Are you more satisfied or less satisfied with the vision you have now compared to your previous vision with glasses and/or contact lenses?” The unit of measure is in Likert scale where 1 = less

218 satisfied, 2 = somewhat less satisfied, 3 = about the same, 4 = somewhat more satisfied, 5 = much more satisfied. “r” stand for Spearman’s rho, is the correlation coefficient, lower the r value less correlated is between the two variables. A positive correlation indicates that higher patient satisfaction was associated with better visual acuity.

Table 6-15 shows that there was a correlation between post-operative uncorrected distance visual acuity but only at survey 4, which coincided with the time when the visual acuity had deteriorated. This may suggest that deterioration in visual acuity causes reduced subjects’ satisfaction scores. However, this was not true with the deterioration of post-operative near visual acuity at survey 4. The lack of correlations at other surveys could be due to the small number of dissatisfied subjects, and type I error. This statistically verifies the speculation made in research questions 1 and 7 earlier on page 162-163 and 167-168.

Research question 20*: Is there any correlation between the change from pre-operative distance BCVA to post-operative UCVA achieved and subjects’ satisfaction (scores in Question 20) at all four surveys in the emmetropic group? (Note, this is a central research question) A bivariate Spearman’s rank-order correlation analysis was performed. Table 6-16. Bivariate Spearman’s rank-order correlation analysis of subjects’ change in distance pre-operative BCVA to post-operative UCVA and their satisfaction. p < 0.01 Change in distance pre-op BCVA and post-op UCVA (emmetropic group) Q20 score N = 186, r = -.11 survey 1 p = 0.15 Q20 score N = 85, r = .08 survey 2 p = .48 Q20 score N = 98, r = -.05 survey 3 p = .63 Q20 score N = 75, r = -.18 survey 4 p = .12 Note: Q20 asked, “Are you more satisfied or less satisfied with the vision you have now compared to your previous vision with glasses and/or contact lenses?” The unit of measure is in a Likert scale where 1 = less satisfied, 2 = somewhat less satisfied, 3 = about the same, 4 = somewhat more satisfied, 5 = much more satisfied. “r” stand for Spearman’s rho, is the correlation coefficient, lower the r value less correlated is between the two variables. A positive correlation indicates that higher patient satisfaction was associated with better visual acuity.

219 Table 6-16 shows that there was no correlation between the change from distance pre- operative BCVA to post-operative UCVA and the subjects’ satisfaction in all four surveys.

Research question 21*: Is there any correlation between the change from pre- to post- distance UCVA and subjects’ satisfaction? (Note, this is a central research question) A bivariate Spearman’s rank-order correlation analysis was performed. Table 6-17. Bivariate Spearman’s rank-order correlation analysis of subjects’ change in pre- to post-operative distance UCVA and their satisfaction. p < 0.01 Change in distance pre- and post-op UCVA (emmetropic group) Q20 score N = 156, r = .05 survey 1 p = .56 Q20 score N = 71, r = -.02 survey 2 p = .89 Q20 score N = 81, r = -.01 survey 3 p = .93 Q20 score N = 62, r = .15 survey 4 p = .26 Note: Q20 asked, “Are you more satisfied or less satisfied with the vision you have now compared to your previous vision with glasses and/or contact lenses?” The unit of measure is in a Likert scale where 1 = less satisfied, 2 = somewhat less satisfied, 3 = about the same, 4 = somewhat more satisfied, 5 = much more satisfied. “r” stand for Spearman’s rho, is the correlation coefficient, lower the r value less correlated is between the two variables. A positive correlation indicates that higher patient satisfaction was associated with better visual acuity.

Table 6-17 shows that there was no correlation between the change from pre- to post-operative UCVA and subjects’ satisfaction in all four surveys. This suggests marked improvement in distance UCVA by itself is evidently not responsible for subjects’ satisfaction. Furthermore, this suggests that subjects could not recall how impaired their unaided distance vision had been, especially those with moderate to high myopia, most of whom could not see more than 50cm. Perhaps other daily function variables may correlate with subjects’ satisfaction, as they may better illustrate the subjects’ perspective with regard to their everyday tasks post- operatively.

220 Research question 22*: Is there any correlation between post-operative residual refractive errors and subjects’ satisfaction? (Note, this is a central research question) A bivariate Spearman’s rank-order correlation analysis was performed. Table 6-18. Bivariate Spearman’s rank-order correlation analysis of subjects’ post- operative residual refractive errors and their satisfaction. p < 0.01 Post-op residual Post-op residual Post-op residual Post-op residual myopic sphere minus cylinder hyperopic sphere plus cylinder Q20 score N = 147, r =.09 N = 123, r = .20 N = 38, r = -.02 N = 30, r = -.04 survey 1 p = .26 p = .03 p = .90 p = .82 Q20 score N = 64, r = -.03 N = 54, r = .31 N = 20, r = -.13 N = 16, r = .17 survey 2 p = .82 p = .02 p = .58 p = .53 Q20 score N = 75, r = .10 N = 61, r = -.11 N = 22, r = -.20 N = 19, r = -.41 survey 3 p = .38 p = .41 p = .38 p = .08 Q20 score N = 54, r = .24 N = 47, r = .18 N = 19, r = .08 N = 14, r = -.79 survey 4 p = .08 p = .22 p = .76 p < .001 Note: Q20 asked, “Are you more satisfied or less satisfied with the vision you have now compared to your previous vision with glasses and/or contact lenses?” The unit of measure is in a Likert scale where 1 = less satisfied, 2 = somewhat less satisfied, 3 = about the same, 4 = somewhat more satisfied, 5 = much more satisfied. “r” stand for Spearman’s rho, is the correlation coefficient, lower the r value less correlated is between the two variables. More post-operative residual sphere or cylinder errors lower the patient satisfaction.

Table 6-18 shows that there was a correlation between residual refractive errors and subjects’ satisfaction, but only with plus cylinder at survey 4, despite persistent under-correction in the myopic sphere and minus cylinder, as well as under- and over-correction in the hyperopic spherical errors as shown in Figures 6-6 to 6-9. This confirms the speculation made in research question 11. The lack of correlation with the other variables could be due to the small number of dissatisfied subjects and type I error. Furthermore, when examining the individual subjects who had greater than one diopter residual refractive error and their satisfaction scores (see Appendix XXXVIIIa), only four subjects rated themselves as “somewhat less satisfied” and one rated “less satisfied”. Each had a specific circumstance (see Appendix XXXVIIIb).

Based on the findings so far, if patient satisfaction does not solely depend on the visual acuity achieved or on residual refractive errors post-operatively, what else contributes to it or affects

221 it? Apart from clinical outcomes or visual acuity, other variables in the satisfaction questionnaire, such as subjects’ ocular comfort, visual ability to perform their daily tasks, subjects’ perception of the surgery outcome, their quality of life post-operatively, may show some association or contributing factors to patient satisfaction.

Research question 23*: Is there any correlation between post-operative binocular UCVA achieved and subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment)? (Note, this is a central research question) A Spearman’s rank-order correlation analysis with post-operative binocular UCVA was performed. Table 6-19. Spearman’s rank-order correlation analysis of subjects’ post-operative binocular uncorrected visual acuity and their responses to the questionnaire. p < 0.01 Post-op. binocular UCVA correlation with At 1 st At 2 nd At 3 rd At 4 th variables in questionnaire survey survey survey survey (N=215) (N=101) (N=110) (N= 90) Experience of pain r = -.007 r = .05 r = -.01 r = .05 p = .92 p = .61 p = .91 p = .64 Experience of irritation r = -.11 r = -.14 r = .09 r = -.11 p = .12 p = .15 p = .33 p = .29 Experience of glare r = -.07 r = .02 r = -.03 r = .06 p = .29 p = .88 p = .74 p = .55 Experience of dry eyes r = .04 r = .04 r = .02 r = .09 p = .61 p = .71 p = .81 p = .41 Rating of unaided distance vision r = .20 r = .08 r = .24 r = .36 p = .004 p = .41 p = .01 p = .001 Rating of unaided near vision r = .21 r = .23 r = .12 r = .17 p = .002 p = .02 p = .20 p = .12 Ability to perform daytime driving r = .16 r = .14 r = .18 r = .23 p = .02 p = .18 p = .05 p = .03 Ability to perform night driving r = .15 r = .08 r = .29 r = .32 p = .03 p = .43 p = .002 p = .002

222 Post-op. binocular UCVA correlation with At 1 st At 2 nd At 3 rd At 4 th variables in questionnaire survey survey survey survey (N=215) (N=101) (N=110) (N= 90) LASIK changes physical activities r = .09 r = .11 r = .14 r = .42 p = .18 p = .30 p = .14 p < .001 LASIK changes social/recreational r = .04 r = .01 r = .14 r = .38 activities p = .57 p = .90 p = .15 p < .001 LASIK improves home activities r = -.06 r = -.08 r = .05 r = .18 p = .35 p = .45 p = .59 p = .10 LASIK improves work activities r = -.10 r = -.15 r = -.009 r = .06 p = .15 p = .15 p = .93 p = .58 LASIK improves overall quality of r = .05 r = -.003 r = .06 r = .17 life p = .44 p = .97 p = .55 p = .12 Information about LASIK given prior to r = .09 r = .02 r = -.02 r = .22 surgery p = .22 p = .81 p = .87 p = .04 Information given about what to expect r = .03 r = -.11 r = .08 r = .15 immediately after the surgery p = .72 p = .28 p = .40 p = .16 Information given about the regime of eye r = -.09 r = -.04 r = .01 r = -.04 drops and medication after the surgery p = .21 p = .73 p = .92 p = .68 Rating of surgery success r = .10 r = .04 r = .07 r = .24 p = .16 p = .71 p = .45 p = .02 Surgery outcomes relative to pre- r = .17 r = .03 r = .17 r = .19 operative expectations p = .02 p = .74 p = .08 p = .07 Satisfaction with the vision now compared to r = .04 r = -.04 r = .03 r = .21 previous vision with glasses/contact lenses p = .58 p = .71 p = .73 p = .05 Note: “r” stand for Spearman’s rho, is the correlation coefficient, lower the r value less correlated is between the two variables. A positive correlation indicates that higher patient satisfaction was associated with better binocular visual acuity in general.

Table 6-19 shows that there was significant correlation between the post-operative binocular UCVA and subjects’ rating of their unaided distance and near vision, ability to drive at night, and perceived improvement in the ability to perform physical, social or recreational activities.

223 Although this study consisted of majority of subjects who had bilateral emmetropic correction, but some had monovision correction and/or unilateral correction to achieved monovision correction, which enable the subjects to performed distance and near daily tasks binocularly. The visual tasks found to have significant correlation reflect this.

From the procedural effectiveness and long-term perspective, this provides excellent insight, as the majority of the correlated variables were identified at survey 4, which may have more credibility as the time elapsed since treatment is the greatest. This finding has some similarity with that of McGhee et al, 136 who found strong correlations between UCVA and sports, viewing television/cinema, daytime driving, reading in daylight and shopping, working with computer, but less strong correlation with night driving and watching television at night.

Research question 24*: Is there any significant difference in the subjects’ responses to the questionnaire between subjects who were satisfied and dissatisfied? (Note, this is a central research question) A set of t-test analyses were performed with the recoded subjects’ satisfaction scores to question 20 (as described in Chapter 5, research question 16, page 142, which consisted of 77% “satisfied” and 23% “dissatisfied” subjects) and the subjects’ responses to all the closed- ended questions at all four surveys. Table 6-20. t-test analyses of significant differences in subjects’ responses to the questionnaire between those who were satisfied and dissatisfied. p < 0.01 Variables of the closed- At 1 st At 2 nd At 3 rd At 4 th ended questions survey survey survey survey (N=215) (N=100) (N=123) (N=122) Experience of pain t = -.1, p = .9 t = -1.2, p = .2 t = -1.2, p = .2 t = -1.1, p = .3 Experience of irritation t = -.7, p = .5 t = -1.3, p = .2 t = .2, p = .8 t = -2.0, p = .05 Experience of glare t = -1.9, p =.1 t = -2.2, p = .2 t=-2.7, p=.009 t = -.4, p = .7

Msat = .8

Mdissat = 1.5 Experience of dry eyes t = -1.3, p =.2 t = -1.4, p = .2 t = -1.3, p = .2 t = -2.1, p = .04 Rating of unaided t = 2.5, p =.01 t = 2.6, p =.01 t = 1.8, p =.08 t = 2.5, p = .02 distance vision Msat = 9.1 Msat = 9.3

Mdissat = 8.6 Mdissat = 8.6

224 Variables of the At 1 st At 2 nd At 3 rd At 4 th closed-ended survey survey survey survey questions (N=215) (N=100) (N=123) (N=122) Rating of unaided near t = .6, p = .6 t = 1.4, p = .2 t = 1.5, p = .1 t = 1.9, p = .06 vision Ability to perform t = 1.3, p = .2 t = 1.0, p = .3 t = 1.2, p = .2 t = 2.4, p = .02 daytime driving Ability to perform night t = 2.1, p =.04 t = 1.6, p = .1 t = 1.8, p =.08 t = 3.4, p = .001 driving LASIK changes physical t = 2.1, p =.04 t = 1.1, p = .3 t = .6, p = .5 t = 2.1, p = .04 activities LASIK changes t = 2.5, p =.01 t = 1.6, p = .1 t = 1.1, p = .3 t = 2.7, p = .01 social/recreational Msat = 4.5 Msat = 4.6 activities Mdissat = 4.1 Mdissat = 4.0 LASIK improves home t =3.4, p=.001 t =3.2, p=.003 t =3.5, p=.001 t = 4.7, p < .001 activities Msat = 4.4 Msat = 4.4 Msat = 4.6 Msat = 4.4

Mdissat = 3.8 Mdissat = 3.7 Mdissat = 4.0 Mdissat = 3.6 LASIK improves work t =3.3, p=.002 t =3.2, p=.002 t =3.0, p=.006 t = 4.8, p < .001 activities Msat = 4.3 Msat = 4.3 Msat = 4.5 Msat = 4.3

Mdissat = 3.7 Mdissat = 3.6 Mdissat = 3.8 Mdissat = 3.3 LASIK improves overall t =2.9, p=.004 t = 1.1, p = .3 t = 2.2, p =.03 t = 2.9, p = .007 quality of life Msat = 4.6 Msat = 4.8

Mdissat = 4.3 Mdissat = 4.2 Information about LASIK t = -.8, p = .4 t = -1.0, p = .3 t = .1, p = .9 t = 2.1, p = .04 given prior to surgery Information given about t = 1.7, p = .1 t = .7, p = .5 t = -.4, p = .7 t = 1.7, p = .1 what to expect immediately after the surgery Information given about the t = 1.2, p = .2 t = 1.2, p = .2 t = .6, p = .6 t = -.2, p = .9 regime of eye drops and medication after the surgery Rating of surgery t = 1.8, p = .1 t =2.7, p=.009 t = 2.4, p =.02 t = 3.8, p = .002 success Msat = 3.8 Msat = 3.9

Mdissat = 3.6 Mdissat = 3.3

225 Variables of the At 1 st At 2 nd At 3 rd At 4 th closed-ended survey survey survey survey questions (N=215) (N=100) (N=123) (N=122) Surgery outcomes t =5.0, p<.001 t =4.5, p<.001 t =3.5, p=.001 t = 4.2, p < .001 relative to pre- Msat = 3.8 Msat = 3.8 Msat = 3.8 Msat = 4.0 operative expectations Mdissat = 3.1 Mdissat = 2.9 Mdissat = 3.1 Mdissat = 3.1

Note: Msat is the mean value of the satisfied subjects. M dissat is the mean value of the dissatisfied subjects.

Table 6-20 shows that there was significant difference between subjects’ satisfaction and their perceived improvement in their ability to perform home and work activities, and surgery outcomes relative to pre-operative expectations in all four surveys. Variables established as significant in two surveys were subjects’ rating of their unaided distance vision, subject’s perceived improvement in the ability to perform social/recreational activities, overall quality of life, and rating of surgery success. Variables established significant at only one survey were amount of glare, and ability to drive at night. The findings show that subjects who were satisfied gave better ratings to these variables than those who were dissatisfied (see Appendix XXXIX). Also, these findings had some consistency with the findings with respect to research question 23, page 222-224.

Research question 25: Is there any significant difference in subjects’ responses to the questionnaire between those who no longer required and those who still required glasses and/or contact lenses post-operatively? A set of t-test analyses were performed with the recoded scores for responses to Question 9 (as described in Chapter 5, research question 25, page 145, which consisted of 74% “no glasses” and 26% “glasses”) and the subjects’ responses to all the closed-ended questions at all four surveys.

226 Table 6-21. t-test analyses of significant difference in subjects’ responses to the questionnaire between those who no longer required and those who still required glasses and/or contact lenses. p < 0.01 Variables of the closed- At 1 st At 2 nd At 3 rd At 4 th ended questions survey survey survey survey (N=215) (N=101) (N=122) (N=123) Experience of pain t = 2.0, p = .05 t = .8, p = .4 t = -.4, p = .7 t = -.1, p = .9 Experience of irritation t = .008, p = 1.0 t = .5, p = .6 t = -.4, p = .7 t = -.03, p =1.0 Troubled by glare t = .6, p = .5 t = .6, p = .5 t = 1.4, p = .2 t = .9, p = .4 Troubled by dry eyes t = .09, p = .9 t = .6, p = .5 t = -.8, p = .4 t = -.9, p = .3 Rating of post-op t = 1.3, p = .2 t = 1.5, p = .1 t = .5, p = .6 t = 2.1, p = .04 unaided distance vision Rating of post-op t = 6.8, p < .001 t =4.3, p<.001 t =4.7, p<.001 t = 5.4, p<.001 unaided near vision Msat = 9.0 Msat = 9.1 Msat = 8.8 Msat = 9.0

Mdissat = 6.2 Mdissat = 6.8 Mdissat = 6.3 Mdissat = 6.3 Rating of vision in t = 1.4, p = .2 t = 1.4, p = .2 t = .9, p = .4 t = 2.0, p = .05 daytime driving Rating of vision in night t = 2.3, p = .03 t = 1.3, p = .2 t = 2.0, p =.05 t = 2.7, p=.008 driving Msat = 8.4

Mdissat = 7.3 LASIK changes physical t = .4, p = .7 t = .7, p = .5 t = 1.5, p = .1 t = 1.0, p = .3 activities LASIK changes t = .05, p = 1.0 t = .4, p = .7 t = 1.1, p = .3 t = .1, p = .9 social/recreational activities LASIK changes home t = 0.7, p = .5 t = -.2, p = .9 t = .7, p = .5 t = .07, p = .9 activities LASIK changes work t = 1.5, p = .1 t = 0, p = 1.0 t = 1.5, p = .1 t = 1.6, p = .1 activities LASIK has improved t = 3.2, p = .002 t = 1.8, p =.08 t = 1.3, p = .2 t = 1.4, p = .2 overall quality of life Msat = 4.6

Mdissat = 4.3 Amount of information t = 2.9, p = .005 t = 2.2, p =.03 t = 2.2, p =.03 t = 2.0, p = .06 given about LASIK prior Msat = 4.7 to surgery Mdissat = 4.3

227 Variables of the closed- At 1 st At 2 nd At 3 rd At 4 th ended questions survey survey survey survey (N=215) (N=101) (N=122) (N=123) Information given about t = .04, p = 1.0 t = .04, p =1.0 t = .4, p = .7 t = .4, p = .7 what to expect immediately after the surgery Information given about the t = .3, p = .7 t = -.5, p = .6 t = 1.2, p = .2 t = 1.2, p = .2 regime of eye drops and medication after the surgery Rating of surgery t = 2.4, p = .02 t = .5, p = .6 t = .2, p = .8 t = 1.3, p = 2.0 success Surgery outcomes t = 2.4, p = .02 t = 1.7, p = .1 t = 1.1, p = .3 t = 2.8, p=.007 relative to pre-operative Msat = 3.9 expectations Mdissat = 3.4 Compare satisfaction with t = .3, p = .8 t = .2, p = .9 t = -2.0, p=.05 t = .5, p=.06 post-op vision to pre-op vision with glasses and/or contact lens

Note: Msat is the mean value of the satisfied subjects. M dissat is the mean value of the dissatisfied subjects.

Table 6-21 shows a statistically significant difference in that those who still required glasses and/or contact lenses post-operatively rated their unaided near vision significantly worse than those who did not in all four surveys. Other variables which established significant differences at only one survey were: ability to drive at night, perceived improvement in overall quality of life, amount of information given prior to surgery, and surgery outcomes relative to pre- operative expectations. These findings show that subjects who still wore glasses and/or contact lenses post-operatively gave worse ratings to these variables than those who no longer required glasses and/or contact lenses (see Appendix XXXX).

Research question 26: Is there any significant difference in satisfaction between male and female subjects? A Chi-Square test for relatedness was performed with the recoded subjects’ satisfaction scores as described in chapter 5 research question 16, page 142.

228 Table 6-22. Chi-Square analysis for significant difference in satisfaction between male and female subjects Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey 1 Male N = 75 N = 24 Chi-square = 0.4 75.8% 24.2% p = 0.5 (p > 0.05, not significant) Female N = 93 N = 24 79.5% 20.5% Survey 2 Male N = 33 N = 18 Chi-square = 1.0 64.7% 35.3% p = 0.3 (p > 0.05, not significant) Female N = 37 N = 13 74.0% 26.0% Survey 3 Male N = 40 N = 13 Chi-square = 1.0 75.5% 24.5% p = 0.3 (p > 0.05, not significant) Female N = 58 N = 12 82.9% 17.1% Survey 4 Male N = 43 N = 13 Chi-square = 0.3 76.8% 23.2% p = 0.6 (p > 0.05, not significant) Female N = 54 N = 13 80.6% 19.4%

Table 6-22 shows that there was no significant difference in satisfaction between male and female subjects.

Research question 27: Is there any significant difference in satisfaction between subjects who are younger than and those who are older than 40 years of age? A Chi-Square test for relatedness was performed with the recoded subjects’ satisfaction scores as described in chapter 5 research question 16, page 142.

229 Table 6-23. Chi-Square analysis for significant difference in satisfaction between subjects who are younger than and those who are older than 40 years of age Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey 1 Younger than N = 77 N = 25 Chi-square = 0.6 40 years 45.8% 52.1% p = 0.4 (p > 0.05, not significant) Older than 40 N = 91 N = 23 years 54.2% 47.9% Survey 2 Younger than N = 32 N = 15 Chi-square = 0.06 40 years 45.7% 48.4% p = 0.8 (p > 0.05, not significant) Older than 40 N = 38 N = 16 years 54.3% 51.6% Survey 3 Younger than N = 42 N = 14 Chi-square = 1.4 40 years 42.9% 56.0% p = 0.2 (p > 0.05, not significant) Older than 40 N = 56 N = 11 years 57.1% 44.0% Survey 4 Younger than N = 38 N = 12 Chi-square = 0.4 40 years 39.2% 46.2% p = 0.5 (p > 0.05, not significant) Older than 40 N = 59 N = 14 years 60.8% 53.8%

Table 6-23 shows that there was no significant difference in satisfaction between younger and older subjects.

Research question 28: Is there any significant difference in the subjects’ responses to the questionnaire between subjects who are younger than and those who are older than 40 years of age? Independent samples t-test analysis showed that there were significant differences between the two groups and the subjects’ rating of unaided near vision (p < 0.001) in all four surveys, overall quality of life (p < 0.001, 0.005 at survey 1 and 2 respectively), and ability to perform social or recreational activities (p = 0.01) at survey 1 only. Subjects who were younger than 40 years of age rated these variables higher than those who were older than 40 years of age (see

230 Appendix XXXXI). These findings contradict the literature.58-60 However, as indicated in Chapter 3, refractive patients are a particular class of patients who have specific expectations and demands of outcomes. It is not surprising, if one considers the probability that the younger patients did not experience presbyopic symptoms, were able to engage in more social or recreational activities, and felt more liberated post-operatively, that they felt they had better quality of life.

Research question 29: Is there any significant difference in satisfaction between myopic and hyperopic subjects? A Chi-Square test for relatedness was performed with the recoded subjects’ satisfaction scores as described in chapter 5 research question 16, page 142. Table 6-24. Chi-Square analysis for significant difference in satisfaction between myopic and hyperopic subjects Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey 1 Myopic N = 116 N = 41 Chi-square = 6.0 73.9% 26.1% p = 0.02 (p < 0.05, significant, Hyperopic N = 46 N = 5 hyperopic patients tended to be 90.2% 9.8% more satisfied) Survey 2 Myopic N = 43 N = 26 Chi-square = 6.0 62.3% 37.7% p = 0.01 (p < 0.05, significant, Hyperopic N = 23 N = 3 hyperopic patients tended to be 88.5% 11.5% more satisfied) Survey 3 Myopic N = 72 N = 21 Chi-square = 1.0 77.4% 22.6% p = 0.3 (p > 0.05, not significant) Hyperopic N = 25 N = 4 86.2% 13.8% Survey 4 Myopic N = 64 N = 19 Chi-square = 0.9 77.1% 22.9% p = 0.4 (p > 0.05, not significant) Hyperopic N = 28 N = 5 84.8% 15.2%

231 Table 6-24 shows that there was significant difference only at surveys 1 and 2, in that the hyperopic subjects were significantly more satisfied with the LASIK procedure than the myopic subjects, despite more residual refractive errors in the hyperopic group as illustrated in Figure 6-8.

Research question 30: Is there any significant difference in post-operative uncorrected distance and near visual acuity achieved between myopic and hyperopic subjects? A t-test analysis showed a significant difference between the two groups but only at surveys 1 and 2 (p < 0.001 and p = 0.002 respectively), in that the myopic subjects achieved better uncorrected distance visual acuity than the myopic subjects (mean = 1.09 vs. 0.97, sd = 0.24 vs. 0.22 at survey 1; mean = 1.07 vs. 0.93, sd = 0.24 vs. 0.24 at survey 2). As for the post- operative near UCVA, the analysis showed that there was no significant difference between the two groups at all four surveys (p = 0.22, 0.57, 0.33, 0.04 respectively). This could be due to small number of hyperopic subjects who had monovision correction.

Research question 31: Is there any significant difference in the subjects’ rating of their unaided distance and near vision (Questions 7a & b in the questionnaire) between myopic and hyperopic subjects? A t-test analysis showed that there was no significant difference in the subjects’ rating of their unaided distance or near vision (Questions 7a & b in the questionnaire) between the two groups at all four surveys (p = 0.04, 0.31, 0.06, 0.02 respectively for distance vision), (p = 0.87, 1.0, 0.49, 0.47 respectively for near vision).

Research question 32: Is there any significant difference in the subjects’ responses to the rest of the questionnaire between myopic and hyperopic subjects? A t-test analysis showed that there were significant differences in three variables: (a) home activities at survey 2 (p = 0.004), in that the hyperopic subjects perceived more improvement in their ability to perform home activities (mean = 4.5 vs. 4.1 sd = 0.6 vs. 1.0 hyperopic and myopic subjects respectively); (b) satisfaction (p = 0.001 and 0.01) at surveys 1 and 2 respectively, in that the hyperopic subjects rated themselves more satisfied with their vision post-operatively compared to previous vision with glasses and/or contact lenses, (mean = 4.6 vs. 4.2, sd = 0.7 vs. 1.0 hyperopic and myopic subjects respectively at survey 1), (mean = 4.5

232 vs. 3.9, sd = 0.8 vs. 1.0 hyperopic and myopic subjects respectively at survey 2); and (c) dry eye at survey 4 (p = 0.003), in that the hyperopic subjects had significantly higher levels of dry eye than the myopic subjects (mean = 1.7 vs. 0.9, sd = 1.5 vs. 1.3 hyperopic and myopic subjects respectively).

Research question 33: Is there any significant difference in satisfaction between subjects who had mild and those who had severe refractive errors pre-operatively (spherical and cylindrical errors were analysed separately)? A 2 x 2 factorial Chi-Square test for relatedness was performed with the recoded subjects’ satisfaction scores as described in chapter 5 research question 16, page 142. Table 6-25 Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 4D myopic spherical errors pre-operatively Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey Less than -4D N = 61 N = 19 Chi-square = 0.47 1 sphere 52.6% 46.3% p = 0.49 (p > 0.05, not significant) More than -4D N = 55 N = 22 sphere 47.4% 53.7% Survey Less than -4D N = 21 N = 12 Chi-square = 0.05 2 sphere 48.8% 46.2% p = 0.83 (p > 0.05, not significant) More than -4D N = 22 N = 14 sphere 51.2% 53.8% Survey Less than -4D N = 38 N = 8 Chi-square = 1.40 3 sphere 52.8% 38.1% p = 0.24 (p > 0.05, not significant) More than -4D N = 34 N = 13 sphere 47.2% 61.9% Survey Less than -4D N = 32 N = 9 Chi-square = 0.04 4 sphere 50.0% 47.4% p = 0.84 (p > 0.05, not significant) More than -4D N = 32 N = 10 sphere 50.0% 52.6%

233 Table 6-25 shows that there was no significant difference in satisfaction between subjects who had less than and those who had more than 4 diopters myopic spherical refractive errors. This finding is consistent with that of McGhee et al. 136

Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 4D minus cylinder errors pre-operatively The table below shows, the sample sizes were too small, expected frequency in at least one category was zero, invalidating Chi-square tests because it is applicable with low N, Fisher’s exact test (2-sided) of significance was used instead. Table 6-26 Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 4D minus cylinder errors pre-operatively Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey Less than -4D N = 86 N = 34 Fisher’s Exact Test p = 1.0 1 cylinder 92.5% 91.9% (p > 0.05, not significant) More than -4D N = 7 N = 3 cylinder 7.5% 8.1% Survey Less than -4D N = 28 N = 22 Fisher’s Exact Test p = 0.45 2 cylinder 82.4% 91.7% (p > 0.05, not significant) More than -4D N = 6 N = 2 cylinder 17.6% 8.3% Survey Less than -4D N = 52 N = 19 Fisher’s Exact Test p = 0.32 3 cylinder 91.2% 100% (p > 0.05, not significant) More than -4D N = 5 N = 0 cylinder 8.8% 0% Survey Less than -4D N = 49 N = 13 Fisher’s Exact Test p = 0.64 4 cylinder 90.7% 86.7% (p > 0.05, not significant) More than -4D N = 5 N = 2 cylinder 9.3% 13.3%

Table 6-26 shows that there was no significant difference in satisfaction between subjects who had less than and those who had more than 4 diopters minus cylindrical refractive errors.

234 Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 3D hyperopic spherical errors pre-operatively The table below shows, the sample sizes were too small, expected frequency in at least one category was zero, invalidating Chi-square tests because it is applicable with low N, Fisher’s exact test (2-sided) of significance was used instead. Table 6-27 Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 3D hyperopic spherical errors pre-operatively Satisfied Dissatisfied Statistics outcomes p < 0.05 Survey Less than +3D N = 23 N = 2 Fisher’s Exact Test p = 1.0 1 sphere 50.0% 40.0% (p > 0.05, not significant) More than +3D N = 23 N = 3 sphere 50.0% 60.0% Survey Less than +3D N = 13 N = 1 Fisher’s Exact Test p = 0.58 2 sphere 56.5% 33.3% (p > 0.05, not significant) More than +3D N = 10 N = 2 sphere 43.5% 66.7% Survey Less than +3D N = 15 N = 0 Fisher’s Exact Test p = 0.04 3 sphere 60.0% 0% (p > 0.05, not significant) More than +3D N = 10 N = 4 sphere 40.0% 100% Survey Less than +3D N = 17 N = 1 Fisher’s Exact Test p = 0.15 4 sphere 60.7% 20.0% (p > 0.05, not significant) More than +3D N = 11 N = 4 sphere 39.3% 80.0%

Table 6-27 shows there was no significant difference in satisfaction between subjects who had less than and those who had more than 3 diopters spherical errors.

Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 3D plus cylindrical errors pre-operatively

235 The table below shows, the sample sizes were too small, expected frequency in more than one category were zero, invalidating Chi-square tests because it is applicable with low N, Fisher’s exact test (2-sided) of significance was used instead. Table 6-28 Correlation between satisfaction vs. dissatisfaction and subjects who had less than vs. those who had more than 3D plus cylinder errors pre-operatively Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey Less than +3D N = 31 N = 3 Fisher’s Exact Test p = 1.0 1 cylinder 96.9% 100% (p > 0.05, not significant) More than +3D N = 1 N = 0 cylinder 3.1% 0% Survey Less than +3D N = 17 N = 2 Could not analyze as no subjects 2 cylinder 100% 100% had more than 3D cylinder More than +3D N = 0 N = 0 cylinder Survey Less than +3D N = 18 N = 2 Fisher’s Exact Test p = 1.0 3 cylinder 94.7% 100% (p > 0.05, not significant) More than +3D N = 1 N = 0 cylinder 5.3% 0% Survey Less than +3D N = 19 N = 4 Could not analyze as no patients 4 cylinder 100% 100% had more than 3D cylinder More than +3D N = 0 N = 0 cylinder

Table 6-28 shows that the sample size was so small that more than one category were zero. It is no surprise to find that there was no significant difference in satisfaction between subjects who had less than and those who had more than 3 diopters plus cylindrical errors.

Research question 34: Is there any significant difference in satisfaction between emmetropic and monovision treated subjects? The Chi-Square test for relatedness was performed with the recoded subjects’ satisfaction scores as described in chapter 5 research question 16, page 142.

236 Table 6-29. Chi-Square analysis of significant difference in satisfaction between emmetropic and monovision treated subjects Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey 1 Emmetropic N = 145 N = 43 Chi-square = 0.7 77.1% 22.9% p = 0.4 (p > 0.05, not significant) Monovision N = 17 N = 3 85.0% 15.0% Survey 2 Emmetropic N = 59 N = 26 Chi-square = 0.001 69.4% 30.6% p = 1.0 (p > 0.05, not significant) Monovision N = 7 N = 3 70.0% 30.0% Survey 3 Emmetropic N = 88 N = 23 Chi-square = 0.04 79.3% 20.7% p = 0.8 (p > 0.05, not significant) Monovision N = 9 N = 2 81.8% 18.2% Survey 4 Emmetropic N = 83 N = 22 Chi-square = 0.05 79.0% 21.0% p = 0.8 (p > 0.05, not significant) Monovision N = 9 N = 2 81.8% 18.2%

Table 6-29 shows that there was no statistically significant difference in satisfaction between the emmetropic and the monovision treated subjects, despite the fact the questionnaire analysis revealed that there were subjects who could not adapt to monovision and expressed dissatisfaction in number of aspects. The lack of significant difference is mostly like due to the small number of dissatisfied subjects who also had monovision correction, thus, the subset was too small to make any meaningful statistical comparison.

Research question 35: Is there any significant difference in satisfaction between subjects who did not and those who required an enhancement? A 2 x 2 factorial Chi-Square test for relatedness was performed with the recoded subjects’ satisfaction scores as described in chapter 5 research question 16, page 142.

237 Table 6-30. Chi-Square analysis of significant difference in satisfaction between subjects who did not and those who required an enhancement Satisfied Dissatisfied Statistical outcomes p < 0.05 Survey 1 No N = 133 N = 33 Chi-square = 2.4 enhancement 80.1% 19.9% p = 0.1 (p > 0.05, not significant) Had at least 1 N = 29 N = 13 enhancement 69.0% 31.0% Survey 2 No N = 53 N = 19 Chi-square = 2.4 enhancement 73.6% 26.4% p = 0.1 (p > 0.05, not significant) Had at least 1 N = 13 N = 10 enhancement 56.5% 43.5% Survey 3 No N = 79 N = 23 Chi-square = 1.6 enhancement 77.5% 22.5% p = 0.2 (p > 0.05, not significant) Had at least 1 N = 18 N = 2 enhancement 90.0% 10.0% Survey 4 No N = 72 N = 20 Chi-square = 0.3 enhancement 78.3% 21.7% p = 0.6 (p > 0.05, not significant) Had at least 1 N = 20 N = 4 enhancement 83.3% 16.7%

Table 6-30 shows that there was no statistically significant difference in satisfaction between the subjects who did not have enhancement and those who required enhancement. This verified the speculation made in research question 10 on page 169. The lack of correlation again may be due to the small number of subjects who had enhancement and were dissatisfied. Also, the subjects’ pre-operative education regarding the nature of the need for enhancement may have played a role.

Research question 36*: Are there variables in the study that can be use as predictors to explain patient satisfaction? (Note, this is a central research question) Logistic regression analysis (see Appendix XXXXII for variables in the equation) was performed

238 Table 6-31. Logistic regression analysis: significant predictors of p < 0.05 patient satisfaction Improvement in ability to perform home activities p = 0.012 Amount of information given prior to surgery p = 0.003 Surgery outcomes relative to pre-operative expectations p <0.001

Table 6-32. Logistic regressive accuracy: classification table Percentage Of Prediction With The Above Predictors Dissatisfied Satisfied Percentage Correct Observed Dissatisfied 15 31 33 Satisfied 5 157 97 Overall 83 percentage

Table 6-31 and 6-32 show the three predictors that could correctly predict the satisfaction level of 83% of the subjects. However, this 83% consisted mostly of satisfied subjects. Only 33% of the less satisfied subjects were correctly classified with these predictors. This suggests that these variables are only partially useful for identifying sources of dissatisfaction. Other variables identified in earlier analyses in relation to research questions 23 to 25, page 222 to 228 and research questions 28 to 32, page 230 to 233, indicated there were other factors contributing to dissatisfaction: amount of glare, rating of unaided distance and near vision, ability to drive at night, changes in ability to perform social/recreational, home and work activities, changes in overall quality of life, amount of information given prior to surgery, rating of surgery success and surgery outcome relative to pre-operative expectations.

It is evident that the study identified small numbers of dissatisfied subjects. This is consistent with the literature, and it was difficult to quantitatively establish meaningful statistical significance in some research aspects. When attempts were made to further identify sources of dissatisfaction by closer examination of the individual dissatisfied subjects, the following factors were relevant: these subjects responded negatively to specific aspects in the questionnaire at more than one survey. They were predominantly subjects who had monovision correction, but could not adapt to it. The second largest subgroup was subjects

239 who had various degrees of dry eyes. The remainder were a few subjects who had residual refractive error, poor night vision, deteriorated unaided vision over time, and difficulty with reading.

240

C H A P T E R 7

Discussion Chapter 7

DISCUSSION Patient satisfaction and improved daily functions are important criteria for assessing the success of a surgical procedure, perhaps even more important than clinical results, as the former aspects are essentially the patients’ testimonial regarding the effectiveness of the procedure. Early studies of patient satisfaction post-PRK were general in nature, so that often the patient’s unwanted signs and symptoms were lost in the analysis. Until 2000 when McGhee et al.136 reported patient satisfaction post-LASIK, there was no research literature on the topic. More sophisticated patient satisfaction studies are now needed in response to more sophisticated patients who are better educated than ever before, due to the competitive nature of refractive surgery as a subspecialty field in ophthalmology. More questions are needed, focusing on the quality of vision and evaluating the reason(s) for subtle dissatisfaction, rather than simply reporting overall satisfaction versus dissatisfaction ratios.

Studies are mandatory to compare findings with other studies, to help put results or findings into perspective. However, it is important that all aspects of the study are comparable. Internal comparison is easier, because the researcher can ensure that all aspects of the methodology are consistent. External comparison is far more difficult to obtain, sometimes even impossible. This can be seen from the literature review, which highlighted the fact that studies have been conducted with different methodologies, patient groups, ranges of pre-operative refractive errors, and quality of data. Furthermore, the comparison of studies of patient satisfaction is even more difficult because of the diversity of the wording of the questions, questions in the questionnaire, and formats of the responses. As stated above, at the time of the current study took place the only related published study can be use for comparison was McGhee et al. 136

There are many distinctive methodologies in the present study which make it different and more sophisticated in comparison to previous patient satisfaction studies post-PRK and LASIK. Some of these differences are: 1. It is a repeated measures design, unlike other studies which were conducted on a static population for a given period, designed merely to describe the treatment outcome. A

241 study is often considered as a snapshot of the phenomenon being investigated. In this study, an analytic method was used to examine a process over time, with the aim of determining why the outcomes were observed, and the impact of the treatment. The repeated measures in this case involved a total of four surveys over a period of two years (and longer for those who had enhancement). This method was chosen to function like a video of an event over time, providing continuous periodical observation to document any dynamic improvement or deterioration at given times after the surgery. This facilitated investigation of whether the observation was stable for all subjects, or whether there was variation for certain subjects with certain specific variables. In turn, possible causal relationship among the variables could be suggested, to explain and identify possible source of satisfaction or dissatisfaction. 2. Because previous studies have not used repeated measure designs, thus, the comparisons between this and previous studies are based on the average of all four surveys. 3. The pre- and post-operative spherical and cylindrical refractive errors in this study were analyzed separately rather than treated as spherical equivalents as in previous studies. This separation allowed changes of magnitude of the sphere and cylinder components to be observed individually. Otherwise the significance of the cylindrical error could be understated and lost in the analysis. 4. Subjects in this study were incidentally sample to maximize the power to be able to generalize to the population and to avoid bias in sampling. 5. This study included a control group of subjects who had a similar refractive profile but did not have LASIK, however, majority of them had new glasses and/or contact lenses prescribed at the end of the first survey as part of their annual refraction up-date. The control group was used to illustrate the effectiveness of LASIK as a treatment, as well as to investigate whether there were any differences in ocular symptoms, visual ability to perform certain daily tasks, which in turn helped to identify what was contributed by the LASIK procedure and what was pre-existing.

242 7.1 Clinical Findings Research questions 1 and 2 assessed the efficacy aspects: the level and the stability of uncorrected distance visual acuity that LASIK subjects achieved post-operatively. The results showed that in the emmetropic group, 40% of subjects achieved UCVA of 6/6 at surveys 1 and 2, and this improved to 45% at survey 4. Thirty eight percent achieved 6/4.5 at survey 1, and this dropped to 19% by survey 4. Statistically, there was significant change, but only between the pre-operative best-corrected and three months post-operative (survey 1) uncorrected visual acuity, in that the pre-operative BCVA was better, and there was no significant change with other surveys. The drop in percentages of 6/4.5 at survey 4 could be due to poor quality of post-operative data under the optometric co-management scheme, as outlined in Chapter 5, page 152-155. Also, it could be attributed to fewer subjects responding and/or fewer subjects achieving 6/4.5 by survey 4. More likely, the subjects who achieved 6/4.5 were very satisfied and fewer of them returned for later surveys (as discussion in chapter 6). When compared with the findings of McGhee et al.,136 the results were noticeably better in the current study. Furthermore, when compared with studies reporting LASIK clinical results in the literature review, such as those of Machet 11 and Linstrom 29 , the results in the current study were better at all levels of visual acuity.

Research question 3 compared the LASIK subjects’ pre-operative BCVA and their 3 months post-operative UCVA versus the BCVA at baseline and 3 months in the control group. The results showed that the LASIK subjects’ pre-operative BCVAs were better and the 3 months post-operative UCVA. The control group’s BCVA was much lower at baseline than that of the treatment group but markedly improved at 3 months, in fact, it slightly surpassed the LASIK subjects’ 3 months post-operative UCVA. Possible explanations may be again due to poor quality of post-operative data as outlined in Chapter 5, or simply the post-operative UCVAs were not as good as the pre-operative BCVA. In the control group, 38 out of 49 subjects had new glasses and/or contact lenses prescribed at the end of survey 1, which allow them to see better at survey 2. This is the first study to track changes in such a group over time. The results indicate that vision is not static in such a control group, one of the probable reason could be due to the fact that majority of the control group subjects had new glasses and/or contact lenses prescribed as part of their annual refraction up-date. Nevertheless, if refractive surgery

243 is to be an alternative to glasses and/or contact lenses one must be able to demonstrate the advantage or disadvantage from one form of intervention to the other, and this study highlight the importance of comparing any intervention to a control.

Research questions 4 and 5 assessed the safety aspect: the level and the stability of best- corrected distance visual acuity achieved by LASIK subjects post-operatively. The results showed that 30% of subjects achieved 6/6 at surveys 1, 2 & 3, and this improved to 43% at survey 4. Fifty seven percent achieved 6/4.5 at survey 1, and this dropped to 33% by survey 4. Statistically, there was significant change, but only between the pre-operative BCVA and survey 1, in that the pre-operative BCVA was better and there was no significant change with other surveys. No other studies have reported this aspect. Instead, the refractive surgery community commonly compares pre- with post-operative BCVA to show lines lost or gained of BCVA, to illustrate the success of the surgery success. As explained in Chapter 5, the reporting of lines of BCVA lost and gained had to be excluded for the reasons have outlined.

Research question 6 compared the LASIK subjects’ pre-operative and their 3 months post- operative BCVA to the BCVA at baseline and 3 months in the control group. The results showed that the LASIK subjects’ pre-operative BCVA was better and declined at 3 months post-operatively. The control group subjects’ BCVA was much lower at baseline than that of the LASIK group, and markedly improved at 3 months, probably with their newly prescribed glasses and/or contact lenses. The declined BCVA at 3 months post-operatively possibly again due to poor quality post-operative data under the optometrist co-management detailed in Chapter 5. If that are so, then there is doubt whether the post-operative BCVA is really the “best-corrected”. Perhaps it should be labelled aided visual acuity instead. The only way to assess this speculation regarding the post-operative UCVA and BCVA data is to have the same parameters measured by the surgeon and the co-management optometrists. Regardless of the outcome of this speculation, from a clinical research perspective, the quality of the post- operative data under the optometric co-management seems to be less than ideal for a number of reasons, as explained in Chapter 5. For these reasons, refractive centres should be cautious when using their data to generate findings.

244 Research questions 7 and 8 dealt with monovision corrected subjects, with regard to the level and the stability of uncorrected near visual acuity LASIK subjects achieved post- operatively. The results showed that 58-68% of subjects achieved N4.5 at surveys 1 and 2 respectively, but this deteriorated to just over 40% at surveys 3 and 4. Statistically, there was no significant change across all four surveys. The drop in percentages of N4.5 at survey 4 could again be due to fewer subjects responding and/or fewer subjects achieving N4.5 by survey 4. Or, more likely, the subjects who achieved N4.5 were very satisfied and fewer of them returned for later surveys. It was speculated that this drop in near visual acuity could affect subjects’ satisfaction. Unfortunately the near visual acuity pre-LASIK, baseline and 3 month data for the control group were not extracted from the subjects’ files, and therefore comparison between the two groups was not possible. No other studies have reported this aspect.

According to the literature, 106,117,119 dissatisfied patients are more likely to withdraw from treatment before completion, particularly when care extends over a period of time, and therefore they are underrepresented in samples of respondents. Thus, as a repeated measures study is known to have different respondent rates in each survey, research question 9 assessed differences in post-operative uncorrected distance, near visual acuity and best-corrected distance visual acuity between subjects who returned for more than one survey and those who returned for only one survey. The results showed that there were no statistically significant differences in post-operative uncorrected distance, near or best-corrected distance visual acuity at survey 1 between subjects who returned for more than one survey and those who returned for only one survey. This lack of difference between the two groups could be due to the fact that only a small number of subjects did not return or to type I error. Nevertheless, there is no evidence in the present survey supporting this previously-reported finding. There was certainly no marked trend for satisfaction to increase over time, as would have happened if dissatisfied subjects had left.

Research questions 10 and 11 dealt with surgical accuracy, asking whether the surgical goal intended matched that achieved, and evaluating the level and stability of residual refractive errors. The results showed that at survey 1 five subjects had unintentionally become

245 monovision instead of emmetropic as planned in one of their eyes. These subjects were in their presbyopic or near presbyopic age and elected to leave the results as they were. Three subjects had monovision corrected in one of their eyes, but disliked the result and had enhancement to become emmetropic. One subject had un-intentionally became emmetropic instead of monovision as planned in one eye, but the subject elected to leave the result as it was. Unfortunately, not all the same subjects returned in surveys 2, 3 and 4, and therefore it was not possible to track and compare the intended versus achieved surgical outcomes over all data collection time points. However, other clinical data such as visual acuity and residual refractive errors showed that the subjects’ surgical results remained the same thereafter. The results showed that 49% of the eyes were free of refractive error and 51% had residual refractive errors. Of the latter, 28% were myopic, 16% were hyperopic, and 8% were astigmatic. There were a small number of myopic spherical over-corrections at surveys 1 and 2, which is consistent with clinical practice to allow room for regression during the healing process. There were also persistent under-corrections in form of the myopic spherical and minus cylindrical refractive errors throughout all four surveys, more with myopic sphere at 24 months or beyond. A direct comparison with those of McGhee et al.136 can not be made, because differences with pre-operative refractive errors and methodology. McGhee et al. 136 based on 48 highly myopic patients (mean pre-operative spherical equivalent was -10.7 + 4.4D). The treatment was done unilaterally so that the outcome of the first eye was used to modify the treatment in the second eye where necessary to minimize residual refractive error. Also, the results were based on one data collection time point, where the post-operative period ranged from 2 to 21 months. However, qualitatively the residual refractive errors were smaller in the current study. The surgery was less effective with hyperopic spherical correction, and there were under- as well as over-corrections throughout all four surveys. The over-corrections reduced by half at 12 to 24 months post-operatively. Some of these over-corrections were intended, to allow room for regression during the healing process. This decrease in accuracy could possibly due to the ablation profile being more complex than that of the myopes. There was no LASIK study reporting hyperopic correction and patient satisfaction at the time when this study took place; however, the clinical results were compared with studies cited by Gimbel and Penno,16 such as those of Ojeimi and Waked and Ditzen et al.. The hyperopic spherical residual errors were much smaller in the current study. The hyperopic or plus

246 cylindrical correction had the same tendency to under-correction as the minus cylinder, but this was more prominent throughout all four surveys. Because previous studies 11,16,29,136 reported only spherical equivalents, comparison was not possible with regard to minus and plus cylindrical errors.

In overview, the current study has not only provided excellent insight regarding the efficacy and the stability of LASIK as a surgical procedure to treat myopic, hyperopic and astigmatic eyes, but it has also shown LASIK to have superior clinical results than those reported in other studies. 11,16,29,136 It was speculated that subjects with unintended results, and/or those requiring enhancement to modify their surgical outcome, and/or those who had residual refractive error greater than one diopter in either the spherical or cylindrical errors or both, might be less satisfied. This speculation is addressed later in this chapter.

As stated earlier on the basis of reports in the literature, 106,117,119 dissatisfied patients are more likely to withdraw from treatment before completion, and they are therefore likely to be underrepresented in the sample of respondents. As this was a repeated measures study of a type known to have different response rates in each survey, research question 12 assessed differences in residual refractive errors between subjects who returned for more than one survey and those who returned for only one survey. The results showed that there was statistically significant difference, but only with the residual minus cylindrical errors, in that the subjects who returned for only one survey had significantly less residual minus cylindrical errors at survey 1 than those who returned for more than one survey. This suggested these subjects achieved better visual acuity and in turn had less residual refractive error, and fewer of them returned for later surveys (see discussion later in this chapter).

7.2 Subjective/Patient Satisfaction Findings The literature review in this study has shown that the evaluation of patient satisfaction is an essential mechanism, as it provides the patients’ perspectives as to how they perceive the impact of the treatment, the functional improvement, and the change in their quality of life post-operatively. Thus, research question 13 assessed the first section of the questionnaire which identified how the subjects learned about LASIK, why they chose LASIK, and what

247 they wanted to achieve from having LASIK. The results showed that the majority of the subjects learned about the LASIK procedure from the media, then smaller proportions learned about it from family, relatives or friends, and from ex-patients. Only 10% learned about it from eye care practitioners and general practitioners. The most common reasons for having LASIK were (in order of frequency) dislike and intolerance of glasses and/or contact lenses, wanting to improve or restore overall vision, for sports and recreational reasons, and wanting a better lifestyle. The remaining minor categories were cosmetic reasons, expense of spectacles, seeing results of ex-patients, occupational reasons and fear of losing spectacles. These findings are consistent with those reported by McGhee et al.136

Research question 14*, one of the central research question of the study dealt with the second section of the questionnaire, which addressed comparisons between the treatment and control groups with regard to subjects’ post-operative ocular symptoms, self-perceived ratings of visual abilities, ratings of visual improvement in performing different activities, and effect on overall quality of life. The results showed that of four ocular symptoms, dry eyes, glare and irritation were the symptoms most frequently complained about post-LASIK. As these aspects were not reported by McGhee et al.,136 comparison across studies was not possible. However, when the LASIK and the control group were compared, there was no significant difference, except with respect to glare and dry eye. The fact that these symptoms were common to both groups suggests that they could have been pre-existing for the LASIK subjects, but that glare and dry eye may have exacerbated post-LASIK. Glare may be transient as the ratings of both the treatment and control group improved over time. The only accurate way to determine whether any of these ocular symptoms was exacerbated by the LASIK procedure would be by comparing them pre- and post-operatively. These findings are interesting as they provide a possible retrospective aspect, and suggest a reason for LASIK subjects’ pre-operative dislike and intolerance of glasses and/or contact lenses – the most common reason given for having LASIK. These findings are also useful illustratively for pre- operative counselling for potential LASIK patients, and these findings are the first to date.

For subjects’ perceptions about their daily visual abilities, the results showed that out of four visual abilities, unaided near vision and vision for night driving respectively were given more

248 low ratings (< 5 out of 10) by subjects. Night driving had the lowest mean scores, suggesting that subjects had the greatest difficulty with it. The findings highlighted the fact that the quality of vision after LASIK may fall short in close work and when light conditions are not optimal. This is consistent with the findings of McGhee et al.,136 who also found that their subjects reported difficulty with reading in artificial light and had significant visual difficulty with night driving. When compared with the control group subjects, although there was no statistically significant difference between the two groups, when the mean scores were examined, vision for night driving and for near or close work were also low. The fact that these visual difficulties were common to both groups suggests that they could be pre-existing conditions. The only way to determine whether they were exacerbated by the LASIK procedure would be to quantify these visual abilities in different lighting conditions pre- and post-operatively.

For subjects’ perceived improvement in vision for performing different activities, the results showed that out of four daily activities, work and home activities had more ratings of “no change” and “worse” respectively than physical and social or recreational activities. These aspects were not reported on by McGhee et al.,136 and therefore comparison was not possible. However, comparisons with the control group showed that there were statistically significant differences, in that the LASIK subjects perceived significantly more improvement in their ability to perform all four activities than the control group. When the mean score were examined, they were very similar in all four activities in the control group, whereas the LASIK group had slightly lower scores for home and work activities. This suggests that even though there was noticeable improvement, it was slightly less for these two activities.

The aim of the LASIK procedure is to reduce or eliminate the need to wear glasses and/or contact lenses. Thus it is essential to assess whether subjects have achieved this goal. The results showed that (figures provided are averages of four surveys) 74% of the subjects were totally free of glasses and/or contact lenses, and 26% still required to wear glasses and/or contact lenses, mostly for some of the time performing specific tasks. Of the latter subjects, 21% mainly wore glasses for near or close work; these were presbyopic subjects who elected to have bilateral emmetropic correction where the need to wear reading glasses was expected

249 and predicted. The remaining 5% of these subjects required glasses and/or contact lenses for distance, near, night driving and dim or low lighting conditions, and a third of these had monovision correction but could not adapt to it. These aspects were not reported by McGhee et al.,136 the lack information in this aspect confirming Waring’s statement that “the published data on how many patients wear spectacles and contact lenses after refractive surgery is almost nonexistent” (p. 213).137 Importantly, the need to wear corrective aids post-operatively had few associations with other variables, and was not associated with satisfaction. This issue is discussed in more detail later in this chapter.

It has been speculated that the source of dissatisfaction often lies in the post-operative symptoms, as this is where the patients indicate that they are having problems. The results showed that 39% of the subjects were asymptomatic, 21% had dry, irritated or red eyes, 36% had blur at near and middle distance, difficulty in poor lighting conditions, night glare, and haloes. This is consistent with the findings in research question 14. Six percent noticed blur in one eye when compared between eyes. Interestingly, this percentage reduced by half from the first to the second year post-operatively. This suggests that by 12 and 24 months after surgery patients have adapted to differences in clarity between the two eyes and no longer consider it a symptom, or simply that the symptom has improved. The remaining minor percentage of post- operative problems consisted of fluctuation of vision, tired and watery eyes, and headaches. These findings have some similarity to those of McGhee at al.,136 except that they did not report any subjects’ ocular discomfort. Many of the symptoms were comparable between the LASIK and the control groups. However, twice as many LASIK subjects complained of difficulty in poor lighting conditions, night glare, and haloes. This is consistent with earlier findings and suggests that these symptoms could be pre-existing and LASIK may have exacerbated them. Symptoms such as dusty dirty sweaty lenses, problems with glasses fitting, and fear and annoyance about misplacing glasses were associated with the control group only.

It has been established in the literature that the aim of having treatment is to improve well- being, which in turn improves quality of life. In this study, 94% of the subjects rated their quality of life as “much improved” and “better”, and 5% considered there was no change. Only 1% rated their quality of life “worse” and “much worse”; these were five subjects who

250 had disparate reasons for their responses: loss of lines UCVA and BCVA, severe dry eyes, inability to adapt to monovision, and severe decentred ablation (waiting for customized enhancement). The results showed that 15% more subjects felt their quality of life had improved than in the study conducted by McGhee at al.136 When compared with the control group, the LASIK subjects perceived significantly greater improvement in their quality of life.

The third section of the questionnaire was relevant to the treatment group only: it dealt with the amount of information given to the subjects before, during, and after the procedure, and whether the subjects had fully understood the information. The results showed that 90% of subjects considered the information given prior to surgery was “excellent” and “good”, and 8% considered it satisfactory. Only 2% stated that not enough information had been given about monovision and its effects, and glare. These results may be compared to the findings of McGhee at al.,136 who reported that 98% of their subjects felt they understood the procedure prior to surgery. In the present study, 84% percent of the subjects stated that the information given immediately after the operation was “excellent” and “good”, 10% stated it was satisfactory, while 6% of the subjects stated there was not enough information given about the possibility of an epithelial defect that causes discomfort and delay of visual recovery, and poorer night-vision post-operatively. The majority of the subjects felt that the instructions given immediately after the surgery regarding eye drops and medications were complete. Only one subject reported having received no information, but did not elaborate. To assess whether the subjects understand what was told prior to surgery, subjects were asked whether, knowing what they knew now, they would still have LASIK. The results showed that 95% of the subjects stated they would still have LASIK, and 3% said “questionable”. Only 2% stated either “probably”, “undecided” or “no”. This subset consisted of most of the subjects mentioned earlier with difficulties such as adapting to monovision, severe dry eyes, corneal flap manipulation, and severe decentred ablation. These aspects were not reported by McGhee et al.,128 and therefore no comparison could be made.

Section 4, part I of the questionnaire assessed subjects’ rating of surgery success, and surgery outcome relative to the pre-operative expectations. It was theorized in the literature that expectations are one of the determinants of satisfaction; thus, meeting subjects’ expectations

251 would suggest satisfaction. The results showed that 97% of the subjects rated the surgery to be “successful” and “very successful”. Only 2% rated it “unsuccessful”, and again these were subjects mentioned earlier with lost of lines in BCVA elected not to have enhancement and severe dry eyes which caused deterioration of UCVA and BCVA. Regarding the outcome of surgery, 90% of subjects stated that it “met” or “greatly exceeded their expectations”. This finding is consistent with that of McGhee at al.136 Only 10% of the subjects felt that it only partially met their expectations; again these were same subjects mentioned earlier with inability to adapt to monovision and had decentred ablation.

If subjects were satisfied with their treatment, would they recommend it to someone else? Research question 15*, one of the central research question of the study assessed whether the subjects recommended one form of treatment over the other when compared between the treatment and the control groups. The results showed that 96% of the subjects stated that they would recommend LASIK, 3% said it would depend on the individual’s eye condition and reasons. Only 1% responded that they were undecided. These were two subjects who responded negatively because they could not adapt to monovision. This aspect was not reported by McGhee et al.136 In comparison with the control group, significantly more LASIK subjects would readily recommending the procedure they had.

From the treatment satisfaction perspective, research question 16*, a central research question of the study assessed subjects’ satisfaction, and compared the responses of the treatment and control groups. The results showed that 77% of the subjects stated that they were “satisfied” and “much more satisfied”, 18% said “about the same”, 5% said “less satisfied”, and 1% were undecided. These findings are similar to those of McGhee et al.,136 who found 97.9% overall patient satisfaction. When the treatment group was compared with the control group there was a statistically significant difference, in that the LASIK subjects were significantly more satisfied than the control group.

Research question 17*, a central research question of the study assessed changes in the subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment) over time, which

252 might help to identify sources of satisfaction or dissatisfaction. The results showed that there were significant changes in only two variables. The first was glare, in that the subjects reported more glare at survey 1, which is consistent with earlier research. Clinically, survey 1 was considered to be the end of stage one in the healing process, when it is not uncommon to find some subjects still complaining of glare. The other variable was the ability to perform work activities, in that the subjects felt there was more improvement in their ability to perform work activities at survey 3. This is a positive insight about the procedure from the long-term perspective, as no ratings for variables worsened significantly over time. As stated earlier on the basis of the literature, 106,117,119 dissatisfied patients are more likely to withdraw from treatment before completion, and they are underrepresented in samples of respondents. Thus, as this was a repeated measures study which is known to have different response rates at each survey, research question 18 assessed differences in the subjects’ responses to the questionnaire at survey 1 between subjects who returned for more than one survey and those who returned for only one survey. The results showed that there was no significant difference between the two groups for any of the 19 variables in the questionnaire at survey 1.

As Aharony and Strasser 104 contended, we still do not know if satisfied patients experience better clinical outcomes. It is possible that they do, but it is also possible for this relationship to be the reverse or even reciprocal. Thus, research question 19*, a central research question of the study assessed the correlation between the uncorrected distance and near visual acuity achieved post-operatively and subjects’ satisfaction (score in question 20). The results showed that there was correlation between post-operative distance UCVA and patients’ satisfaction but only at survey 4, which coincided with the time when the visual acuity had deteriorated. This may suggest that deterioration in visual acuity caused subjects’ reduced satisfaction scores, but this was not the case with the deterioration of post-operative near visual acuity at survey 4. The lack of correlations at other surveys could be due to the small number of dissatisfied subjects, and type I error. This speculation was statistically verified with regard to research question 1 and 7 in Chapter 6.

Research questions 20* and 21* were the central research questions of the study that assessed the correlation between the change from pre-operative distance BCVA to post-

253 operative UCVA achieved and subjects’ satisfaction (scores in question 20), and the correlation between the change from pre- to post-operative distance UCVA and subjects’ satisfaction at all four surveys in the emmetropic group. The results showed that there was no statistically significant correlation between the change from pre-operative distance BCVA to post-operative UCVA and subjects’ satisfaction, nor between the change from pre- to post- operative distance UCVA and subjects’ satisfaction in all four surveys. This may suggest that despite the clinical evidence of marked improvement in the majority of subjects, subjectively patients tended not to remember how bad their unaided distance vision had been, especially those who had been moderate to high myopes, most of whom could not see more than 50cm away unaided pre-operatively. These findings are consistent with the literature.110,113,136 Steinberg et al.110 found the correlation between visual acuity and patients’ satisfaction with their vision to be zero.

Research question 22*, a central research question of the study assessed the correlation between the subjects’ post-operative residual refractive errors and their satisfaction. The results showed that there was statistically significant correlation but only with plus cylindrical errors at survey 4, despite persistent under-correction in the myopic sphere and minus cylinder, as well as under- and over-correction in the hyperopic spherical errors as shown in Figures 6-7 to 6-9. The lack of correlations with the other variables could be due to small number of dissatisfied subjects and type I error. This finding statistically confirmed the speculation made earlier with regard to research questions 10 to 12 in Chapter 6, page 169- 175. It also confirms the consensus from the literature review that patient satisfaction is not unidimensional and is not related solely to clinical outcomes. If patient satisfaction does not depend solely on clinical outcomes or on visual acuity achieved post-operatively, what else contributes to it or affects it? McGhee et al.136 indicated that while patients might be highly satisfied with the overall outcome, they might be dissatisfied with individual components. They found strong correlations between UCVA and sports, viewing television/cinema, daytime driving, reading in daylight and shopping, and working with the computer, but less strong correlation with night-time driving and watching television at night.

254 Research question 23*, one of the central research question of the study assessed the correlation between the subjects’ post-operative binocular UCVA achieved and their responses to the questionnaire regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment. The results showed that variables correlated with post-operative binocular UCVA were: • rating of unaided distance vision (in three out of four surveys) • ability to drive at night (in two out of four surveys) Variables had significant correlation only at survey 1 were: • rating of unaided near vision • improved ability to perform physical, and social or recreational activities

From the procedure effectiveness and long term perspective, these findings provide excellent insight, as the majority of the correlated variables were identified at survey 4, giving more credibility as the time elapsed was the longest since treatment. These findings have some similarity with those of McGhee et al.136 who found strong correlations between UCVA and sports, viewing television/cinema, daytime driving, reading in daylight and shopping, and working with the computer, but less strong correlation with night-time driving and watching television at night.

Research question 24*, a central research question of the study assessed differences in the subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment) between subjects who were satisfied and dissatisfied. The results showed that factors associated with subject satisfaction in all four surveys were: • improved ability to perform home and work activities • surgery outcomes had met or exceeded pre-operative expectations Variables established as significant at two surveys: • positive rating of unaided distance vision • improved ability to perform social or recreational activities • improved overall quality of life • positive rating of surgery success

255 Variables established as significant at only one survey: • amount of glare • ability to drive at night. These findings show that subjects who were satisfied gave better ratings to these variables than those who were dissatisfied. Also, these findings had some consistency with the findings reported in relation to research question 23. McGhee et al.136 found poor to no correlation between overall satisfaction and functional aspects, improved quality of life outcome and achieving goals.

If the aim of having the LASIK procedure was to be independent of glasses and/or contact lenses, it was speculated that subjects who still required glasses and/or contact lenses post- operatively would respond to the questionnaire negatively. Thus, research question 25 assessed differences in subjects’ responses to the questionnaire (regarding ocular symptoms, rating of visual abilities, quality of life, treatment outcome and satisfaction of treatment) between those who no longer required and those who still required glasses and/or contact lenses post-operatively. The results showed that subjects who still required glasses and/or contact lenses post-operatively rated the following significantly worse at all four surveys: • unaided near vision The following were significantly worse at only one survey: • ability in night driving • information given prior to surgery • quality of life • surgery outcomes relative to pre-operative expectation. There were no differences between the groups in satisfaction. Although absence of evidence is not proof of absence, there remains no evidence that satisfaction is generally affected by need to wear correction post-operatively. This is one of the most striking findings from the survey.

Reports in the literature 58-60,63-65,126 have shown significant differences in satisfaction between male and female, younger and older patients. Thus, research questions 26, 27 and 28 assessed differences in satisfaction between male and female subjects, between subjects who were

256 younger than and those who were older than 40 years of age, and their responses to the questionnaire. The results showed that there were no statistically significant differences in satisfaction between male and female subjects, younger and older subjects. However, there were significant differences in their responses to the questionnaire, in that the younger subjects rated their unaided near vision, overall quality of life and improved ability to perform social or recreational activities better than did the older subjects. These findings contradict the literature;58-60,63-65,126 however, as indicated in Chapter 3, refractive patients are a different class of patient, who have specific expectations and demands of outcomes. It is not surprising, if one considers the probability that the younger subjects did not experience presbyopic symptoms, were able to engage in more social or recreational activities, and felt more liberated post-operatively, that they felt they had better quality of life. These findings have some similarity with those of McGhee et al.,136 who found that their younger subjects had a higher overall satisfaction score than older subjects and were more satisfied with UCVA, reading, and shopping.

The study revealed that hyperopic correction might not be as affective as myopic correction, due to the greater incidence of under- and overcorrection, which led to the speculation that hyperopic subjects might be less satisfied than myopic subjects. Thus, research question 29 assessed differences in satisfaction between myopic and hyperopic subjects. The results showed that there was a statistically significant difference but only in surveys 1 and 2, in that the hyperopic subjects were more satisfied with the LASIK procedure than were the myopic subjects. This is consistent with clinical observation that hyperopic subjects were happy in the initial post-operative stage as they could see at near distances unaided for the first time. Patients are often told that as the healing process unfolds their vision will change due to regression. There was no significant difference between hyperopic and myopic subjects at surveys 3 and 4. Possibly once the healing process finished, patient satisfaction was the same between the two groups. Perhaps the hyperopic patients were more satisfied earlier because they achieved better visual acuity, and hence gave better ratings in the questionnaire. Thus, research questions 30, 31 and 32 assessed differences in post-operative distance and near UCVA achieved, and whether the subjects perceived and responded to the questionnaire differently between the myopic and hyperopic subjects. The results showed that not only did

257 the hyperopic subjects not achieve better post-operative distance UCVA, they were worse at surveys 1 and 2. There was no significant difference in near visual acuity between the two groups, which could be due to the small number of hyperopic subjects who had monovision correction. Furthermore, the hyperopic subjects did not perceive and rate their unaided distance and/or near vision to be better; however, they rated themselves as significantly more satisfied with their vision post-LASIK compared to their previous vision with glasses and/or contact lenses at surveys 1 and 2, perceived more improvement in their ability to perform home activities at survey 2, but had significantly worse dry eye than the myopic subjects at survey 4.

It was speculated that subjects with severe refractive errors pre-operatively had more impaired unaided vision, thus, more noticeable visual improvement post-operatively and perhaps they were therefore more satisfied than those who had milder refractive errors. Thus, research question 33 assessed differences in satisfaction between subjects who had mild and those who had severe refractive errors pre-operatively. The results showed that there was no statistically significant difference in satisfaction between subjects who had less than and those who had more than 4 diopter myopic spherical errors. This finding is consistent with that of McGhee et al. 136 As for the hyperopes, there was no significant difference in satisfaction between subjects who had less than and those who had more than 4 diopter minus cylindrical errors, less than and more than 3 diopter hyperopic spherical and cylindrical errors. The lack of significant difference could be due to the small number of subjects with more severe sphere and cylinder errors, especially among the hyperopes.

The study revealed that there were subjects who could not adapt to monovision post- operatively also responded negatively throughout the questionnaire. Perhaps dissatisfaction might correlate with monovision treated patients. Thus, research question 34 assessed differences in satisfaction between emmetropic and monovision treated subjects. The results showed that there was no statistically significant difference. The lack of significant difference is mostly like due to the small number of dissatisfied subjects who also had monovision correction.

258 If the aim of LASIK was to reduce or eliminate refractive errors, but the surgical result did not achieve the intended target and the subjects required enhancement(s), would the subjects be less satisfied? Research question 35 assessed differences in satisfaction between subjects who did not and those who did require an enhancement. The results showed that there was no statistically significant difference. This confirms the speculation earlier in relation to research questions 10 and 11, and the lack of significant difference is again maybe due to the small number of dissatisfied subjects who also had enhancement. Also, the subject’s pre- operative education regarding the nature of the need for enhancement may have played a role.

Lastly, in accordance with Carey,143 a survey such as this should at least assess the multiple R- square from a regression model. To meet this criterion, research question 36*, one of the central research question of the study dealt with this aspect and revealed that three predictors could correctly predict the satisfaction level of 83% of the subjects. These predictors were (i) improvement in ability to perform home activities, (ii) amount of information given prior to surgery, and (iii) surgery outcome relative to pre-operative expectations. At first glance, these might be considered to be excellent predictors, as most studies have been able to explain less than 20% 87 of the variance in satisfaction. However, this 83% consisted mostly of satisfied subjects. Only 33% of the less satisfied subjects were correctly classified with these predictors. This finding suggests that these variables are only partially useful for identifying sources of dissatisfaction. Other variables identified in the earlier analyses in research questions 23 to 25 and 28 to 32 indicated that there were other contributing factors, such as amount of difficulty with glare, rating of unaided distance and near vision, ability to drive at night, changes in ability to perform social/recreational, home and work activities, changes in overall quality of life, amount of information given prior to surgery, rating of surgery success, and surgery outcome relative to pre-operative expectations.

The marked discrepancy between the ability to predict satisfaction and dissatisfaction is consistent with the conclusions that satisfaction and dissatisfaction are not opposite ends of a continuum, but are at least partly separate processes. If they were opposites it would be reasonable to expect that both could be predicted equally well by the same predictors. Clearly, that is not the case. The difference in success of predicting satisfaction and dissatisfaction

259 would occur if satisfaction were a more unitary or global state than dissatisfaction. It may be that dissatisfaction, like pain, tends to be more focused than pain-free good health. If this is the case, satisfaction could potentially be assessed globally, as well as by specific questions about specific issues. Dissatisfaction may need to be assessed in relation to specific foci. Such speculation is consistent with the findings in this study that although most subjects would undergo the procedure again if they had to choose, a number of them had specific dissatisfaction.

It is evident that throughout this study there were a small number of dissatisfied patients, and as common in a repeated measures study there were different response rates at each survey. More than one survey had only a small number of respondence, which reduced the sample size even further. Consequently it is difficult to quantitatively analyse and establish meaningful statistical significance to answer some of the research questions. In order to further identify sources of dissatisfaction, closer examination was given to the responses of the less satisfied or dissatisfied subjects. It is apparent that the following factors were relevant: • The subjects responded negatively to specific aspects in the questionnaire at more than one survey. • Within this group of subjects, the largest subgroup was those who had monovision correction and could not adapt to it. Consequently, they were among the subjects who indicated that they still required glasses and/or contact lenses either for reading, distance, night driving or the combined, post-operatively. • The second largest subgroup was subjects who had various degrees of dry eyes. • The remainders were a few subjects who had residual refractive error, poor night vision, deteriorated unaided vision over time, and had difficulty with reading.

260

C H A P T E R 8

Conclusion Chapter 8

CONCLUSION It is evident from the literature review that the evaluation of patient satisfaction has been an essential mechanism to assess medical care or treatment outcomes. The literature on patient satisfaction is abundant, but it also reveals a number of weaknesses and contradictory findings. The main difficulties in this field of research stem from lack of conceptualization and theories as to what constitutes patient satisfaction. The literature does, however, provide theorized ideas and suggestive formulas as to what patient satisfaction is comprised of, and ways to quantify it. It suggested that one should use “the right horses for the right courses”123 (p. 60); in other words, the design of an investigation should be appropriately customized to one’s objective. Furthermore, an investigation should define and measure not only what patient satisfaction means to the service providers, but also which aspects are important to patients and what makes them satisfied.

The literature also suggests the use of both direct as well as closed- and open-ended questionnaire formats with carefully framed, patient-centred focus questions. The closed- ended question response format should also include a multidimensional scale to increase variability and provide an adequately sensitive measure, so that the responses are more likely to reveal differences in medical care and treatment outcome as well as changes over time. This way the information gained will supplement ratings of overall satisfaction, because although individuals will report satisfaction or dissatisfaction with particular aspects of their care, they may not give sufficient priority to mentioning specific aspects spontaneously in response to an open-ended question. By such measures, one can prevent the under-reporting of events of less significance which is largely due to information not being elicited by interview or questionnaire techniques. It seems likely that direct questions that function as probes to elicit dissatisfaction with aspects of care or treatment have less impact on respondents than open- ended questions. For this reason, the closed- and open-ended question combination allows subjects to describe their experiences of care or treatment and to comment on favourable or unfavourable aspects of their experience. Closed-ended questions will give better indication of patient priorities, while open-ended questions can be rated to produce satisfaction scores. Ideally, any discrepancies between the two ought to be detectable by the investigator. Data

261 obtained in this way can be handled in three ways: (i) unstructured responses can be sorted, categorized as favourable or critical and counted, (ii) comparisons across variables can then be made on the basis of the ratio of favourable to critical comments, and (iii) the comparisons can be appropriately analyzed to identify variables that are predictive of patient’s satisfaction or dissatisfaction. This study has implemented as many of these recommendations as possible and has identified some consistency with the findings of previous studies, but also has revealed some new insights that are unique to this form of research.

The literature review showed that traditional clinical measures such as visual acuity and refraction inadequately describe the visual outcomes and experience of post-refractive surgery. Other factors, such as contrast sensitivity, different lighting conditions required for different visual tasks, and the so called “quality of vision”, may account for some variation in patient satisfaction. However, these parameters are rarely used in everyday pre- or post-operative assessment, and accurate observations about the quality of vision are often difficult to measure, simply because there is no reliable way to quantify them, even with measurement of visual acuity, contrast sensitivity, and glare tests. The literature has suggested that functional vision changes do occur after LASIK. The optical quality of the cornea is reduced and the asphericity becomes oblate. Changes in functional vision worsen as the target contrast diminishes and the pupil size increases. These findings indicate that the oblate shape of the cornea following LASIK is the predominant factor responsible for the functional vision decrease. These findings are consistent with clinical observation, especially in high myopic and hyperopic treated eyes. For these reasons, the treatable refractive ranges diminished by the late 1990s. This is evidenced by the different levels of refractive error documented in the study of McGhee et al.136 and the present study. As wavefront guided technology emerged in 2000, it became an additional instrument to assess higher order aberration in the human optical system, which is supposed to provide a better clinical understanding of the human optical errors, a step toward assessing the “quality of vision”. However, not all refractive clinics use this wavefront technology for pre- or post-operative assessment. Therefore, despite the advances in instrumentation, mainstream clinical measurements are still based on visual acuity and refraction, especially in post-operative follow-ups.

262 There seems to be some imbalance of importance between the pre- and post-operative clinical evaluation. More specifically, the pre-operative clinical evaluation involves meticulous subjective refraction by the surgeon with the aim to correct and achieve the best possible visual acuity sometimes as high as 6/3, along with other diagnostic assessments such as orbscan topography, and lately wavefront analysis, all of which measure to as small as 0.1 diopter of corneal power and/or 1 micron of corneal thickness. However, post-operatively when the assessment is done by the co-management optometrists, not only do many of the follow-ups possibly lack the meticulous attention in refraction, but some optometrists may not refract beyond 6/6, and different visual acuity charts are used, some of which may not measure visual acuity beyond 6/6. More importantly, these optometrists do not have the diagnostic instruments that were used in the pre-operative assessment.

All these discrepancies are considered acceptable in the refractive surgery community. This is evidenced in the clinical data of this study, where it was found that only visual acuity, subjective refraction and slit lamp examination were conducted post-operatively. When pre- and post-operative visual acuity data were compared, the LASIK subjects’ post-operative distance UCVA was worse than their pre-operative BCVA, and declined at 3 months. By 24 months post-operatively only 19% of the subjects achieved 6/4.5. Furthermore, in comparisons between the LASIK and non-LASIK subjects (the control group), the LASIK subjects’ UCVA at 3 months post-operatively dropped below the non-LASIK subjects’ BCVA. This drop in percentages could be attributed to poor quality of post-operative data, or to the fact that fewer patients responded and/or that fewer subjects achieved 6/4.5 at the fourth survey. More likely, the subjects who achieved 6/4.5 were very satisfied and fewer of them returned for later surveys. Comparison of pre- and post-operative BCVA had the same trend, but the decline was less prominent at 3 months postoperatively. In comparisons between the LASIK and the control group subjects, the LASIK subjects’ BCVA at 3 months post-operatively did not fall below the control group’s BCVA. A possible explanation could be the lack of meticulous attention in the post-operative assessment, resulting in poor quality post-operative data, as outlined in Chapter 5. The only way to determine whether there is any difference in the post- operative UCVA and BCVA data would be to have the same parameters measured by the surgeon and the co-management optometrists. Another possible explanation is simply that the

263 LASIK subjects’ post-operative uncorrected distance visual acuity was inferior to their preoperative BCVA. As for the non-LASIK subjects, with their newly prescribed glasses and/or contact lenses, they too achieved good and even better visual outcomes than the LASIK procedure. If this is case, the vision achieved by refractive surgery with its advanced technologies may still fall short of non-LASIK vision with glasses and/or contact lenses. Patients must be informed about this possible outcome. As wavefront technology emerges, it is claimed that LASIK with this technology can achieve post-operative UCVA better than vision with glasses and/or contact lenses. This may be an ambitious claim that needs to be confirmed.

Nevertheless, the results of this study showed LASIK to be effective in correcting myopia, hyperopia and astigmatism, so long as it was within the demarcation safety guidelines. The study showed persistent under-correction in the myopic spherical and minus cylindrical refractive errors throughout all four surveys, more with myopic sphere at 24 months or beyond. Hyperopic spherical correction was less effective, in that there were under- as well as over-corrections throughout all four surveys. The over-corrections reduced by half at 12 to 24 months post-operatively. Some of these over-corrections are intentional, to allow for regression during the healing process. This inaccuracy could possibly be attributed to the ablation profile being more complex than that of the myopes. The hyperopic or plus cylindrical correction had the same tendency of under-correction as the minus cylinder, but this was more prominent throughout all four surveys. Nonetheless, there was no statistically significant change to the myopic, hyperopic sphere, minus and plus cylindrical residual refractive errors in all four surveys.

According to literature, 106,117,119 dissatisfied patients are more likely to withdraw from treatment before completion, particularly when care extends over a period of time, and therefore they are under-represented in samples of respondents. This was a repeated measures study, a type that is known to have different response rates in each survey. The results of this study showed that there was no significant difference in post-operative distance and near UCVA or in distance BCVA, but subjects who returned only for survey one had significantly less residual minus cylindrical errors at survey 1 than those who returned for more than one

264 survey. This confirms the speculation that subjects who achieved better visual acuity and in turn had less residual refractive error were very satisfied, and fewer of them returned for later surveys. The clinical results in this study are comparable and in most aspects superior to those of published studies. 11,16,29,136

Unlike clinical outcomes, the patient’s own judgment regarding the success of an operation is far more complex, as patients have various levels of motivation, expectations and visual requirements. Also, patients’ ability to recall the effect of their visual ability in daily tasks pre- operatively varies. The lack of pre-operative baseline data in this and all previous post-PRK and LASIK studies,21,111-113,128-136 imposes limitations on interpretation of post-operative functional improvement, visual symptoms or difficulties. One reason for this is that originally this study was designed to assess patients’ perceived treatment outcome, and the emphasis was on the patients’ perceptions of post-operative aspects. Fortunately, this study included the control group (the non-LASIK subjects), whose role was not only to compare the effectiveness of the LASIK procedure with that of glasses and/or contact lenses, but also, because they had the same refractive profile and characteristics as the LASIK patients, to compare and demonstrate the commonality in ocular symptoms and visual ability to perform daily tasks. Information about the control subjects facilitated definition of common strengths and weaknesses between the two groups, and also to some extent acted as pre-operative data.

The findings of this study are consistent with those of McGhee et al.136 However, the comparison between the LASIK and the control group revealed some interesting new insights that were previously undocumented. The study found that dry eye, glare problems and irritation were the symptoms most frequently complained of post-LASIK. When these symptoms were compared with the control group, there was no significant difference except for the larger proportion of subjects complaint of glare problems and dry eye in the LASIK group. The fact that these symptoms were common to both groups may suggest that they were pre-existing for the LASIK subjects, but that glare problems and dry eye were exacerbated post-LASIK. However, glare may be transient, as both the treatment and control groups improved over time in that respect. The only way to determine whether any of these ocular symptoms were exacerbated by the LASIK procedure is to compare them pre- and post-

265 operatively. This finding is also a useful illustrative tool for pre-operative counselling for potential LASIK patients.

Visual tasks such as near vision, night driving, home and work activities were areas of difficulty in post-LASIK subjects, but in the control group night driving and near vision also attracted low ratings. The fact that these visual difficulties were common to both groups may suggest that they were pre-existing conditions. The only way to determine whether they were exacerbated by the LASIK procedure would be to quantify these visual tasks in different lighting conditions pre- and post-operatively. Also, the comparison showed that the LASIK subjects perceived significantly more improvement in their ability to perform physical, social or recreational, home and work activities than the control group, but the LASIK group had slightly lower scores for home and work activities, indicating that the overall prominent improvement was slightly less for these two activities.

The study showed that 26% of the subjects still needed to wear glasses and/or contact lenses. Among those, 21% were presbyopic subjects who elected to have bilateral emmetropic correction, and for whom the need to wear reading glasses was expected and predicted. The remaining 5% required glasses and/or contact lenses for distance, near, night driving and dim or low lighting conditions; a third of these subjects had monovision correction but could not adapt to it.

It has been established in the literature that the aim of having treatment is to improve well- being, which in turn improves quality of life. From the LASIK subjects’ perspective, 94% of them rated their quality of life as “much improved” and “better”, and 5% said there was no change. Only 1% rated it “worse” and “much worse”. This 1% included subjects who had loss of lines UCVA and BCVA, dry eyes, could not adapt to monovision, and severe decentred ablation respectively. The findings showed a higher proportion of improvement in quality of life than those of McGhee et al.136 Furthermore, the LASIK subjects perceived significantly more improvement in their quality of life than the control group.

266 In today’s medicine, the emphasis on informed consent is higher than ever, and litigation is becoming a common practice, especially in refractive surgery. Thus, it was important to investigate how fully informed the subjects were and how fully they understood the information. The majority of the subjects stated they were fully informed prior to and immediately after the surgery, and during after-care. Only 2% stated that not enough information had been given about monovision and its effect, and glare, and 6% stated there not enough information had been given about epithelium defect and poorer night-vision post- operatively.

It has been theorized in the literature that expectations are one of the determinants of satisfaction; thus, meeting patients’ expectations would suggest satisfaction. The study showed that 97% of the subjects rated their surgery to be “successful” and “very successful”, 90% stated that the surgery outcome “met” and “greatly exceeded” their expectations. Only 10% felt that it partially met their expectations; these were the subjects whose residual problems were detailed earlier. Only 1% of the subjects would hesitate to recommend LASIK, because they could not adapt to monovision. Compared with the control group, significantly more LASIK subjects would readily recommend LASIK than control group subjects would recommend glasses and/or contact lenses. The study also showed that 77% of the subjects stated that they were “satisfied” and “much more satisfied” with their vision post-operatively, 18% said their vision was “about the same” as their previous vision with glasses and/or contact lenses, and 5% were “less satisfied”. Compared with the control group, the LASIK subjects were significantly more satisfied with the improvement in their vision.

The literature could not demonstrate whether satisfied patients experience a better clinical outcome. It is possible that they do, but it is also possible for this relationship to be the reverse or even reciprocal. In this study there was a correlation between postoperative distance UCVA and patient satisfaction scores, but only at survey 4, which coincided with the time when visual acuity had deteriorated. This is partially consistent with the speculation that deterioration in visual acuity caused the drop in patient satisfaction scores. However, this was not true of the deterioration of post-operative near UCVA at survey 4. Also, there was correlation between post-operative residual refractive errors and patient satisfaction scores,

267 except with plus cylindrical errors at survey 4. The lack of correlation found at earlier surveys could be due to the small number of dissatisfied subjects, and type I error. The finding is consistent with the writings of Steinberg et al.110 and Monestam et al.,113 confirming the concept that patient satisfaction is not unidimensional and is not related to outcome solely in terms of visual acuity and residual refractive errors. If this is the case, what else contributes to patient satisfaction or affects it? McGhee et al.136 indicated that while patients might be highly satisfied with the overall outcome, they might be dissatisfied with individual components. This study showed that variables correlated with post-operative binocular UCVA were: • rating of unaided distance vision (in three out of four surveys) • ability to drive at night (in two out of four surveys) Variables had significant correlation only at survey 1 were: • rating of unaided near vision • improved ability to perform physical, and social or recreational activities

From the perspective of the procedure long-term, this provides excellent insight by virtue of the fact that the majority of the correlated variables were found at survey 4, which may have more credibility as the time elapsed is the greatest since treatment. The finding has some similarity with that of McGhee et al.136

The study showed that, apart from good unaided distance and near visual acuity, factors positively associated with patient satisfaction were: • not being troubled by glare • good night driving vision • improvement in the ability to perform social or recreational activities, home and work activities • improvement in overall quality of life • positive rating of surgery success • surgery outcome meeting or exceeding pre-operative expectations.

268 It has been speculated that subjects who still required glasses and/or contact lenses post- operatively would respond to the questionnaire more negatively. The study showed that these subjects rated the following significantly worse at all four surveys: • unaided near vision (at all four surveys) The following were significantly worse at only one survey: • night driving ability • amount of information given prior to surgery • quality of life • surgery outcomes relative to pre-operative expectation

The results showed no statistically significant difference in satisfaction between male and female subjects, younger and older subjects. However, the younger patients rated their unaided near vision, overall quality of life, and ability to perform social or recreational activities significantly better than the older subjects did. These findings contradicted those in the literature.58-60,63-65,126 However, as indicated in Chapter 3, refractive patients are a different class of patients who have specific expectations and demands of outcomes. It is not surprising, if one considers that the younger patients probably did not experience presbyopic symptoms, were able to engage in more social or recreational activities, and felt more liberated postoperatively, that they felt that they had better quality of life. The findings have some similarity with those of McGhee et al.,136 whose younger subjects had a higher overall satisfaction score than their older subjects and were more satisfied with UCVA, reading, and shopping.

The study showed that hyperopic correction was not as effective as that for myopia because of a greater incidence of under- and over-correction postoperatively. This finding led to the speculation that the hyperopic subjects might be less satisfied than myopic subjects. However, the results showed that the hyperopic subjects were significantly more satisfied in the first 6 months, not because they achieved better clinical results, but they perceived more improvement in their ability to perform home activities, although they had significantly higher level of dry eyes than the myopic subjects.

269 It has been speculated that patients with severe refractive errors pre-operatively had more impaired unaided vision, and thus would perceive more noticeable visual improvement post- operatively and perhaps would be more satisfied than those who had milder refractive errors. The results showed no statistically significant difference in satisfaction between mild and severely myopic, hyperopic and cylindrical refractive errors. The lack of significant difference is most likely due to the small number of subjects with high sphere and cylinder errors, especially hyperopes. Thus, no meaningful statistical comparison could be made.

The study showed that there were subjects who could not adapt to monovision post- operatively and who been responded negatively throughout the questionnaire, and one might think it is safe to assume that they would be less satisfied. However, the results showed no statistically significant difference in satisfaction between emmetropic and monovision corrected subjects. It should be noted that the number of dissatisfied subjects who also had monovision correction was small. Nevertheless, this finding further confirms the speculation of McGhee et al.136 that while patients might be highly satisfied with the overall outcome, they might be dissatisfied with individual components. Also, the study found no significant difference in satisfaction between subjects who did not and those who did require enhancement. Undoubtedly, the discrepancy in visual acuity and refractive error between the two eyes that existed at the time of the data collection must play a role and have an effect on the patient satisfaction. The lack of dissatisfaction related to these two aspects may again be due to the small number of dissatisfied patients; also pre-operative patient education may have played a role.

As suggested in the literature,143 surveys should at least assess the multiple R-square from a regression model. Thus, the logistic regression found that three predictors could correctly predict the satisfaction level of 83% of the patients. They were: • an improvement in the ability to perform home activities • the amount of information given prior to surgery • surgery outcomes that met or exceeded pre-operative expectations. However, this 83% consisted mostly of satisfied patients, and only 33% of the less satisfied patients were correctly classified using these predictors. This suggests that whereas factors

270 associated with satisfaction are predictable, sources of dissatisfaction are more idiosyncratic. This is consistent with literature 15,95-97 in that satisfaction scales represent a continuum, and satisfaction is not necessarily the opposite of dissatisfaction. The findings suggest that these variables are only partially useful for identifying sources of dissatisfaction. Other contributing factors which were identified in the early analyses were amount of glare, rating of unaided distance and near vision, ability to drive at night, the change in ability to perform social/recreational, home and work activities, the change in overall quality of life, amount of information given prior to surgery, rating of surgery success, and surgery outcome relative to pre-operative expectations. These variables demonstrated distinctive differences between subjects who were satisfied and dissatisfied.

It is evident that there were only a small number of dissatisfied subjects, which reflects the fact that LASIK is highly effective as a refractive procedure. However, the skewed data among satisfied and dissatisfied subjects and many other variables made it difficult to quantitatively establish meaningful statistical comparisons. Closer examination of the dissatisfied subjects revealed disparate markers of dissatisfaction, which were: • subjects responded negatively to specific questions in the patient satisfaction questionnaire in more than one survey • subjects had monovision correction, but could not adapt to it • subjects complained of various degree of dry eyes • subjects had residual refractive error • subjects had poor night vision • subjects had deterioration of unaided vision over time • subjects had difficulty with reading.

Undoubtedly, future studies must include and compare pre- and post-operative data, as it is the best way to quantify the impact of visual symptoms and visual functions post-LASIK. It is preferable that the post-operative data is not constrained by the optometric co-management, due to the problems outlined. Also, if a better way to quantify the so-called quality of vision was available in the future it would provide better understanding of vision difficulties in dim or poor lighting conditions pre- and post-LASIK. Despite the increased focus on satisfaction

271 as an outcome measure and a growing body of research, satisfaction has remained difficult to compartmentalize. The factors individual patients use to deem themselves satisfied or dissatisfied remain unclear. One thing is certain, this study has illustrated that one cannot calculate patient satisfaction or dissatisfaction by a mathematic equation, as it is multidimensional in nature, and varies in content and strength. The complexity of the relationship between variations in patients’ education, emotion, mental state, motivation, purpose and expected benefit gain for having the LASIK procedure, and their needs of subjective visual ability in everyday life is dynamic and complex in its own right. The literature 95,100 suggests that rather than to try to understand and follow the less theorized concept of patient satisfaction, researchers should conduct more qualitative studies to capture and understand the attitudes, feelings and beliefs that patients express about their medical encounter or treatment experience.

This is a useful starting point for developing a framework that generates a patient-centred approach to a systematic content analysis of patients’ written comments in self-administered surveys, or verbal comments given during interviews, that will tell researchers what is important to study and what is salient to patients’ treatment experiences. With this information at hand, researchers would be in a better position to understand the cognitive and affective processes of how patients form attitudes and make causal attributions. Future studies should not only deal with the relationship between patient satisfaction attitudes and clinical outcomes, but they should also explore the relationship between patient satisfaction or dissatisfaction and the subsequent behaviours these attitudes may cause. The study has shown the standard of patient satisfaction studies has been improving slowly, but it needs more work to be able to balance the evaluation of its clinical counterpart. As technologies continue to improve, refractive patients will continue to be better educated and will increase their demands and expectations of visual outcome. Also, by identifying that the control group changed over time in several measures, the study has demonstrated that satisfaction does not remain constant in a non-LASIK sample. Any future study of LASIK should include a comparison group. Lastly, it is likely that personality traits or psychological profiles will contribute some influence to patients’ satisfaction, especially when dealing with “hard to please” patients. The unwritten contraindications to refractive surgery are: patients with unrealistic expectations or

272 underlying personality disorders, or patients who hope that LASIK will change their lives to overcome certain significant life transitions such as divorce, loss of job, recovery from depression or simply emotional turmoil, and patients who have limited understanding of the risks involved with the procedure. Discussion of these conditions requires a separate thesis in itself, but it is important that surgeons recognize and set limitations on whether or not to perform surgery on these patients, as no outcome is likely to be satisfactory.

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285 Glossary

Ablation – a procedure used in laser refractive surgery where corneal tissues are removed by excimer laser.

Aphakia – absence of crystalline lens of the eye, usually after cataract extraction.

Applanation – a procedure that measures intraocular pressure by measuring the force required to flatten a small area of central cornea.

BCVA – abbreviation for best-corrected visual acuity.

Blepharitis – inflammation of the eyelids usually associated with redness of the eyes, swelling lids, tear film debri and itchiness and/or soreness of the eyes.

Blepharostat – hindrances by eyelid and/or speculum while cutting the corneal flap.

Bullous – describes a degenerative condition characterized by small blister-like pockets and/or fingerprint-like defects that form in the swollen corneal epithelial layer. This markedly reduces vision.

Circle of least diffusion – area within astigmatic image (conoid of Sturm) where defocused vertical and horizontal meridians produce the smallest, clearest image.

Coma – an optical aberration where image distortion occurs for points that lie off-axis, such image points appearing comma-shaped instead of dot-like.

Cylinder correction – an optical correction that produces specific refractive power in each meridian or specific degree of axis. It is used for correcting the astigmatism component of the refractive error.

Deturgescence – the mechanism by which the stroma of the cornea remains relatively dehydrated.

DLK – abbreviation for diffuse lamellar keratitis, an inflammation condition described a diffuse white, granular, culture-negative keratitis that occurs under the corneal flap.

Ectasia – a pathologic condition that describes the thin, stretched sclera or cornea. In the cornea it refers to the abnormal bulging forward of thinned cornea, such as with keratoconus.

286 It can be congenital, but in refractive surgery it is induced as the treatment has removed too much corneal tissue, causing decompensation of the corneal structures.

Enhancement – further laser treatment to refine and correct under- and overcorrected refractive errors

Epiphoric – commonly known as having wateriness of the eye(s), commonly caused by a defect in the tear drainage system or by excessive production of tears.

Epithelial defect – a defect that occurs at the outermost layer of the cornea accompanied by loss of superficial corneal tissue. It is commonly known as corneal abrasion.

Exenteration – a surgical procedure that removes the eyeball, leaving eye muscles and remaining orbital contents intact. It is also known as enucleation.

Keratitis – corneal inflammation characterized by loss of lustre and transparency, and cellular infiltration.

Keratoconus – a hereditary and sometimes surgically induced pathologic condition. A degenerative corneal disease characterized by generalized thinning and cone-shaped protrusion of central and/or inferior cornea. Usually affects vision. If it is hereditary it involves both eyes and occurs during the second decade of life.

Keratocyte – the fibroblastic stromal cell of the cornea.

Lateral canthotomy – surgical procedure where a horizontal incision is made at the lateral junction of the upper and lower lids (canthi) to temporarily enlarge lid separation to increase eye exposure.

Lenticule – lens-shaped material, often corneal donor tissue used in some types of refractive surgery.

LogMAR – a type of visual acuity measurement scale uses in a LogMAR visual acuity chart. The scale is based on the logarithm of the minimal angle of resolution.

Lyophyllize – to use a laboratory technique describing a freeze-dry method of removing water (dehydration) from tissue.

287 Minus cylinder – the state in which a toric lens has maximum minus-power in one meridian or specific degree of axis. It is used for correcting the minus astigmatism component of refractive errors.

Monovision – at least one of the eyes is corrected to enable the person to read or do close work unaided post-operatively.

Optical zone – the diameter of an ablation profile which is aligned from the pupilary centre of the eye during PRK and/or LASIK treatment. The depth of ablation increases exponentially with the square of the optical zone size. The aim is to use the largest optical zone possible, commonly 6.0mm or more, to minimize poor night vision and halos as the pupil dilates at night or in dim lighting conditions.

Pachymetry – a measuring procedure to determine the corneal thickness of the eye.

Pannus – a pathologic condition in which abnormal blood vessels and fibrous tissue have infiltrated the cornea just under its surface.

Plus cylinder – the state in which a toric lens has maximum plus-power in one meridian or specific degree of axis. It is used for correcting the plus astigmatism component of refractive errors.

Snellen Visual acuity – visual acuity measured using Snellen chart. A visual acuity chart consist of rows of letters, numbers, or symbols in standardized graded sizes, with a designated distance usually 6.0 metres at which each row should be legible to a normal eye.

Speculum – a surgical instrument used to hold the eyelids apart during surgical procedures, giving better access to the eyeball.

Topolink – a refractive procedure which uses topographical information to link into the computerized excimer laser delivery system to specifically treat a customized area of the cornea.

Trephine – a surgical cutting tool that makes a circular hole or demarcation in the corneal tissue. This instrument is used in the LASEK procedure where a lamellar corneal pseudo-flap is created prior to the excimer laser removing the underlining corneal tissues.

288 Type I error – Statistically, if one reject Ho, the null hypothesis (accept Ha, the alternative hypothesis) when in fact Ho is true, this is a Type I error.

Type II error – Statistically, if one accept Ho (reject Ha ) when in fact Ha is true, this is a Type II error.

UCVA – abbreviation for uncorrected visual acuity.

289 Appendices

APPENDIX I: Survey questionnaire for the treatment group. The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

1. How did you first learn about the LASIK procedure?

______

2. Who referred you to this centre or surgeon?

______

3. What was the PRIME objective for having LASIK?

______

4. What Were the other reason(s) for having LASIK?

______

5. What was your PRIME desired end result (e.g. distance vision without glasses)?

______

6. Are you currently having any of the following: Please circle one. NOTE: 0=none 1=mild 3=moderate 5=severe PAIN 0 1 2 3 4 5 IRRITATION 0 1 2 3 4 5 GLARE 0 1 2 3 4 5 DRY EYES 0 1 2 3 4 5

7. How do you rate the level of vision without glasses or contact lenses in the following daily activities? Please circle one. NOTE: 1 = inability to perform the activity because of visual difficulty 10 = no problem DISTANCE VISION 1 2 3 4 5 6 7 8 9 10 NEAR VISION 1 2 3 4 5 6 7 8 9 10 DAYTIME DRIVING 1 2 3 4 5 6 7 8 9 10 NIGHT DRIVING 1 2 3 4 5 6 7 8 9 10

290 8. Are there any changes in your vision which affected or improved your ability to perform the following tasks; much worse worse no change better much improved PHYSICAL ACTIVITIES [ ] [ ] [ ] [ ] [ ] SOCIAL/RECREATIONAL ACTIVITIES [ ] [ ] [ ] [ ] [ ] HOME ACTIVITIES [ ] [ ] [ ] [ ] [ ] WORK ACTIVITIES [ ] [ ] [ ] [ ] [ ]

9. Do you need to wear any glasses or contact lenses now? If yes, for what purpose?

______

10. If any, what is the ONE MAIN symptom that you are experiencing?

______If you have more than one symptom you may list others.

______

11. In your opinion, has the surgery had any effect in your overall quality of life? (Please tick one) much worse worse no different better much improved [ ] [ ] [ ] [ ] [ ]

12. Was enough information given to you about LASIK prior to the surgery? (Please tick one) almost nothing not enough satisfactory good excellent [ ] [ ] [ ] [ ] [ ]

13. Was enough information given to you as what to expect immediately after the surgery? (e.g. pain, glare, blur) (Please tick one) almost nothing not enough satisfactory good excellent [ ] [ ] [ ] [ ] [ ]

14. How much information were you given regarding the regime of using eye drops, and medication? (Please tick one) none some complete [ ] [ ] [ ]

15. How would you rate the success of the surgery? (Please tick one) very unsuccessful mod. unsuccessful mod. successful very successful [ ] [ ] [ ] [ ]

291 16. How do you compare your satisfaction now with your pre-operative expectations? (Please tick one) [ ] surgery outcomes did not at all meet expectations [ ] surgery outcomes partially met expectations [ ] surgery outcomes met expectations [ ] surgery outcomes slightly exceeded expectations [ ] surgery outcomes greatly exceeded expectations

17. Now that you have undergone the surgery, knowing what you know now, would you still have the surgery?

______

18. Would you have the second eye done if required?

______

19. Would you recommend LASIK to someone else?

______

20. Are you more satisfied or less satisfied with the vision you have now compared to the vision you had previously with glasses or contact lenses?

Much more satisfied some what more satisfied about the same some what less satisfied less satisfied [ ] [ ] [ ] [ ] [ ]

292 APPENDIX II: Reliability analysis for the treatment group questionnaire.

R E L I A B I L I T Y A N A L Y S I S - S C A L E (A L P H A) N of Cases = 209.0 N of Items = 19 Alpha = 0.7177 When five items (questions 6a, b, c, d and question 14) were deleted, the reliability coefficient increased as follows: N of cases = 211.0 N of Items = 14 Alpha = 0.7718. Thus the alpha coefficient was found to be acceptable.

293 APPENDIX III: Survey questionnaire for the control group. The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

1.Do you currently wear glasses or contact lenses? If yes, for what purpose? (a) Glasses______(b) Contact lenses______

2a. While wearing your glasses do you have any 2b. While wearing your C.L. do you have any Pain 0 1 2 3 4 5 Pain 0 1 2 3 4 5 Irritation 0 1 2 3 4 5 Irritation 0 1 2 3 4 5 Glare 0 1 2 3 4 5 Glare 0 1 2 3 4 5 Dry eyes 0 1 2 3 4 5 Dry eyes 0 1 2 3 4 5 NOTE: 0 = none 1 = mild 3 = moderate 5 = severe

3.If any, what is the ONE MAIN SYMPTOM or ANNOYANCE that you are experiencing? ______If you wish you may list other symptoms or annoyances. ______

4.How you rate the level of your vision with glasses and/or contact lenses in the following daily activities? NOTE: 1 = inability to perform the activity due to visual difficulty 10 = no problem Distance vision 1 2 3 4 5 6 7 8 9 10 Near vision 1 2 3 4 5 6 7 8 9 10 Daytime driving 1 2 3 4 5 6 7 8 9 10 Night driving 1 2 3 4 5 6 7 8 9 10

5.Think back to the time you last had your eyes examined (about 6 months ago), are there any changes in your vision which have affected or improved your ability to perform the following tasks;

294 much worse worse no change better much improved Physical activities [ ] [ ] [ ] [ ] [ ] Social/recreational activities[ ] [ ] [ ] [ ] [ ] Home activities [ ] [ ] [ ] [ ] [ ] Work activities [ ] [ ] [ ] [ ] [ ]

6.Think back to the time you last had your eyes examined (about 6 months ago), what effect has wearing glasses and/or contact lenses since then had on your overall quality of life? much worse worse no different better much improved [ ] [ ] [ ] [ ] [ ]

7.How happy are you that you need to wear glasses and/or contact lenses to achieve normal (or close to 6/6) vision? very dissatisfied moderately dissatisfied moderately satisfied very satisfied [ ] [ ] [ ] [ ]

8.If money was not a factor, would you have chosen laser surgery to correct your refractive error (near or far-sighted)? definitely probably unsure probably not definitely not [ ] [ ] [ ] [ ] [ ]

9.Would you recommend glasses and/or contact lenses to someone else? ______

295 APPENDIX IV: Reliability analysis for the control group questionnaire.

R E L I A B I L I T Y A N A L Y S I S - S C A L E (A L P H A) N of Cases = 45.0 N of Items = 19 Alpha = 0.6778 When two items (questions 6 and 8) were deleted, the reliability coefficient increased as follows: N of cases = 47.0 N of Items = 17 Alpha = 0.6994. Thus the alpha coefficient was found to be acceptable.

296 APPENDIX V: Distribution of ages in the treatment group subjects.

7

6 6

5

4 4 4 4 4 4 4 3 3 3 3 3 3

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 Percent 20.00 26.00 32.00 38.00 44.00 50.00 56.00 62.00 69.00 23.00 29.00 35.00 41.00 47.00 53.00 59.00 65.00

The graph above shows that 43.06% of the subjects were less than or equal to 39 years of age and 56.94% of the subjects were more than or equal to 40 years of age.

297 APPENDIX VI: Distribution of ages in the control group subjects.

14

12 12

10 10

8

6 6 6

4 4 4 4 4 4 4 4 4

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

0 Percent 19.00 30.00 40.00 47.00 52.00 56.00 61.00 26.00 35.00 44.00 49.00 54.00 58.00 65.00

The graph above shows that 22.3% of the subjects were less than or equal to 39 years of age and 77.1% of the subjects were more than or equal to 40 years of age.

298 APPENDIX VII: Information sheet for the treatment group.

The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

INFORMATION SHEET

The title of the research project is “THE SUCCESS OF LASIK - CORRELATION BETWEEN CLINICAL SUCCESS AND PATIENT SATISFACTION.” The project investigates the success of the LASIK procedure you have had and your impression of satisfaction with the results.

The procedure of the project is non-invasive, non-contact, and does not use any form of medication. The project has been approved by the University of Sydney’s Human Ethics Committee.

When you attend the refractive clinic for your postoperative check-up, you will be given a questionnaire to answer, which measures your impression of the LASIK procedure you have had. The whole session will takes approximately 15 minutes. Some of your clinical information relevant to this project will be extracted with your and the surgeon’s permission.

Your privacy and identity are completely confidential. You can withdraw anytime without any explanation or prejudice. You will be informed about the outcome as soon as the project is completed.

Any person with concerns or complaints about the conduct of this study can contact the Secretary of the Human Ethics Committee, University of Sydney, on (02) 9351 4811.

Thank you Yours sincerely, Lien Tat.

299 APPENDIX VIIIa: Consent form for the treatment group - researcher’s copy.

The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

CONSENT FORM – Researcher’s Copy

I, ______Voluntarily consent to participate in the research project entitled, THE SUCCESS OF LASIK – CORRELATION BETWEEN CLINICAL SUCCESS AND PATIENT SATISFACTION conducted by Lien Tat, as part of a post graduate research degree (Doctor of Philosophy of Applied Science) at the University of Sydney. The procedure as set out in the attached information sheet has been explained to me and I understand what is expected of me and the benefits and risks involved. I have had all of my questions concerning my participation in the study answered to my satisfaction.

I acknowledge that I have the right to question any part of the procedure, and that I can withdraw at anytime without this being held against me. I understand that the information obtained from this research may be obtained from my medical file and be published. However, my right to privacy will be maintained in that no personal details will be revealed.

Signature of Subject:______

Name of Witness: ______

Signature of Witness: ______

Date: ______

300 APPENDIX VIIIb: Consent form for the treatment group - participant’s copy.

The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

CONSENT FORM – Researcher’s Copy

I, ______Voluntarily consent to participate in the research project entitled, THE SUCCESS OF LASIK – CORRELATION BETWEEN CLINICAL SUCCESS AND PATIENT SATISFACTION conducted by Lien Tat, as part of a post graduate research degree (Doctor of Philosophy of Applied Science) at the University of Sydney.

The procedure as set out in the attached information sheet has been explained to me and I understand what is expected of me and the benefits and risks involved. I have had all of my questions concerning my participation in the study answered to my satisfaction.

I acknowledge that I have the right to question any part of the procedure, and that I can withdraw at anytime without this being held against me. I understand that the information obtained from this research may be obtained from my medical file and be published. However, my right to privacy will be maintained in that no personal details will be revealed.

Signature of Subject:______

Name of Witness: ______

Signature of Witness: ______

Date: ______

301 APPENDIX IX: Covering letter for subjects who had recently had their clinical data collected.

Dear (Amanda),

I understand you had your clinical follow-up recently. It would be greatly appreciated if you could take a moment to complete the attached questionnaire and return it in the envelope provided as soon as possible.

If you have any questions please do not hesitate to contact me on 02 9386 3622. Yours truly, Lien Tat.

302 APPENDIX X: Information sheet for the control group.

PARTICIPANT INFORMATION SHEET

As part of a research project titled “THE SUCCESS OF LASIK - CORRELATION BETWEEN CLINICAL SUCCESS AND PATIENT SATISFACTION.” The project investigates the success of the LASIK procedure, but it also assess your impression or satisfaction with the current method of visual aid(s) namely glasses and/or contact lenses.

The procedure of the project is non-invasive, and does not use any form of medication. The project has been approved by the University of Sydney’s Human Ethics Committee.

When you visit your Optometrist for an initial or review assessment, you will be given a questionnaire to answer, which measures your impression or satisfaction of the glasses or contact lenses you are using. This will takes approximately 10 minutes. Some of your clinical information relevant to this project will be extracted with your and the optometrist’s permission. Then three months later, you will be contacted and a phone survey will be conducted to ask how you are doing visually with your current or new glasses and/or contact lenses if new set was prescribed at the last visit. This will take approximately 10 minutes.

Your privacy and identity are completely confidential. You can withdraw anytime without any explanation or prejudice. You will be informed about the outcome as soon as the project is completed.

Any person with concerns or complaints about the conduct of a research study can contact the Secretary of the Human Ethics Committee, University of Sydney, on (02) 9351 4811.

THANK YOU Yours sincerely, Lien Tat (investigator)

303 APPENDIX XIa: Consent form for the control group – researcher’s copy.

The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

CONSENT FORM – Researcher’s Copy

I, ______Voluntarily consent to participate in the research project entitled, THE SUCCESS OF LASIK – CORRELATION BETWEEN CLINICAL SUCCESS AND PATIENT SATISFACTION conducted by Lien Tat, as part of a post graduate research degree (Doctor of Philosophy of Applied Science) at the University of Sydney.

The procedure as set out in the attached information sheet has been explained to me and I understand what is expected of me and the benefits and risks involved. I have had all of my questions concerning my participation in the study answered to my satisfaction.

I acknowledge that I have the right to question any part of the procedure, and that I can withdraw at anytime without this being held against me. I understand that the information obtained from this research may be obtained from my medical file and be published. However, my right to privacy will be maintained in that no personal details will be revealed.

Signature of Subject:______

Name of Witness: ______

Signature of Witness: ______

Date: ______

304 APPENDIX XIb: Consent form for the control group – participant’s copy.

The University of Sydney Faculty of Health Sciences School of Applied Science PO Box 170 Lidcombe NSW 2141 Australia

CONSENT FORM – Participant’s Copy

I, ______Voluntarily consent to participate in the research project entitled, THE SUCCESS OF LASIK – CORRELATION BETWEEN CLINICAL SUCCESS AND PATIENT SATISFACTION conducted by Lien Tat, as part of a post graduate research degree (Doctor of Philosophy of Applied Science) at the University of Sydney.

The procedure as set out in the attached information sheet has been explained to me and I understand what is expected of me and the benefits and risks involved. I have had all of my questions concerning my participation in the study answered to my satisfaction.

I acknowledge that I have the right to question any part of the procedure, and that I can withdraw at anytime without this being held against me. I understand that the information obtained from this research may be obtained from my medical file and be published. However, my right to privacy will be maintained in that no personal details will be revealed.

Signature of Subject:______

Name of Witness: ______

Signature of Witness: ______

Date: ______

305 APPENDIX XII: Additional questions in survey 2 – phone survey for the control group.

Thank you for your assistance in completing the first survey in December when you saw (Mr M.F.) (the optometrist).

This is just a follow-up procedure, where I would like to confirm the following with you: • Were you given new glasses and/or contact lenses prescription during the last visit?

______

• Did you made up the new prescription? Was it for glasses or contact lenses?

______

• Are you still wearing those particular glasses and/or contact lenses?

______

• Are you happy with the vision the glasses and/or contact lenses provide?

______

Comment:______

306 APPENDIX XIII: Covering letter with additional questions in survey 2 for the control group for subjects who were uncontactable.

Dear (Gary),

Thank you for your assistance in completing the first survey in December when you saw (Mr M.F.) (the optometrist).

This is just a follow-up procedure, where I would like to confirm the following with you: • Were you given a new glasses and/or contact lenses prescription in the last visit?

______

• Did you made up the new prescription? Was it for glasses or contact lenses?

______

• Are you still wearing that particular glasses and/or contact lenses?

______

• Are you happy with the vision the glasses and/or contact lenses provides?

______

Comment:______

It would be greatly appreciated if you could take a moment to complete the enclosed questionnaire and return in the envelope provided.

Thank you. Yours sincerely, Lien Tat.

307 APPENDIX XIV: Reminder letter 1 for the treatment group - to remind subjects they were due for post-operative review.

Dear (A),

How are you? You are due for review following your LASIK procedure.

Thank you for completing the recent survey. It is time again! Please take a moment to complete the enclosed questionnaire and return it in the envelope provided or bring it with you when you come to see me.

Next week will be six months since your procedure/enhancement. It would be in your best interest to have a review preferably at the refractive clinic. I am more than happy to arrange this for you. Please contact the refractive centre, and ask for Lien.

If you have been allocated a local optometrist and you prefer to go there or you have already had a review with your local Optometrist recently, please state on the questionnaire who the optometrist was so I can chase up the report, and please disregard this letter.

If you have any questions please do not hesitate to contact me on 02 9386 3666. Yours truly, Lien Tat

308 APPENDIX XV: Reminder letter 2 for the treatment group - for subjects who did not respond to previous reminders.

Dear (J), How are you? You are due for review following your LASIK procedure.

Thank you for completing the last survey. It is time again! Please take a moment to complete the enclosed questionnaire and return it in the envelope provided or bring it with you when you come to see me.

I have noticed that you have not had your review(s) and I have not received any report from your optometrist since your treatment/enhancement procedure. Perhaps you have been away or the mail of my last reminder got lost. It would be in your best interest to have a review preferably at the refractive clinic. I am more than happy to organize that for you. Please contact the refractive centre, and ask for Lien.

If you have been allocated a local optometrist and you prefer to go there or you have already had a review with your local optometrist recently, please state on the questionnaire who the optometrist was so I can chase up the report, and please disregard this letter.

If you have any questions please do not hesitate to contact me on 02 9386 3666. Yours truly, Lien Tat

309 APPENDIX XVI: Reminder letter 1 for the control group - for subjects who were uncontactable.

Dear (Gary),

Thank you for your assistance in completing the first survey in December when you saw (Mr M.F.) (the optometrist). I have been trying to contact you without success, perhaps you have been away or the mail of my last reminder got lost.

This is just a follow-up procedure, where I would like to confirm the following with you: • Were you given new glasses and/or contact lenses prescription during the last visit? ______

• Did you made up the new prescription? Was it for glasses or contact lenses?

______

• Are you still wearing those particular glasses and/or contact lenses?

______

• Are you happy with the vision the glasses and/or contact lenses provide?

______

Comment:______

It would be greatly appreciated if you could take a moment to complete the enclosed questionnaire and return it in the envelope provided.

Thank you. Yours sincerely, Lien Tat.

310 APPENDIX XVII: Reminder letter 2 for the control group - for subjects who did not respond to previous reminders.

Dear (Gary),

Thank you for your assistance in completing the first survey in December when you saw (Mr M.F.) (the optometrist). I have been trying to contact you without success, perhaps you have been away or the mail of my last reminder got lost.

This is just a follow-up procedure, where I would like to confirm the following with you: • Were you given new glasses and/or contact lenses prescription during the last visit? ______

• Did you made up the new prescription? Was it for glasses or contact lenses?

______

• Are you still wearing those particular glasses and/or contact lenses?

______

• Are you happy with the vision the glasses and/or contact lenses provide? ______

Comment:______

It would be greatly appreciated if you could take a moment to complete the enclosed questionnaire and return it in the envelope provided.

Thank you. Yours sincerely, Lien Tat.

311 APPENDIX XVIII: Research question 9; result of independent samples t-test analysis between post-operative uncorrected distance, near or best-corrected distance visual acuity at survey 1 between subjects who returned for more than one survey and those who returned for only one survey, p. 168-169.

Variables Statistical analysis outcomes Post-operative distance UCVA t = -1.8, p = 0.08 (p > 0.01, not significant) Post-operative distance BCVA t = -1.5, p = 0.14 (p > 0.01, not significant) Post-operative near UCVA t = 1.1, p = 0.08 (p > 0.01, not significant)

312 APPENDIX XIX: Research question 10; emmetropic and monovision results achieved from pre-operative status to 24 months post-operatively, pp. 169.

Category Pre-op 3 months 6 months 12 months 24 months R eye L eye R eye L eye R eye L eye R eye L eye R eye L eye Not bilateral, but 8 4 8 4 7 5 8 5 8 5 unilateral Tx for monovision Emmetropic 188 164 185 162 92 80 108 93 80 70 Monovision 20 47 20 43 10 28 16 29 11 24 Unintended 3 2 2 - 1 - - 1 monovision Disliked & had - 3 - 1 - 3 - 1 enhancement to remove monovision Unintended - 1 - - 1 2 - 1 emmetropic Unilateral 1 - 1 1 - 1 - 1 - emmetropic (the only healthy eye) Subtotal 216 216 216 216 112 114 135 132 100 102 Missing data - - 104 102 81 84 116 114 Total 216 216 216 216 216 216 216 216 216 216

313 APPENDIX XXa: Histogram of residual myopic spherical errors at 3 months post-op.

Attempted vs Achieved Myopic Sphere at 3 months Post-op.

2 1.5

1 0.5 Achieved 0

Post-op (D) Post-op -0.5 -1 -1.5 -16 -14 -12 -10 -8 -6 -4 -2 0 Pre-op (D)

○ indicates one subject with a slightly larger residual sphere: patient 108 with pre-op sphere -7.70D, at 3 months post-op. it was overcorrected by +1.50D. It would be interesting to see what happens at later follow-ups.

314 APPENDIX XXb: Histogram of residual myopic spherical errors at 6 months post-op.

Attempted vs Achieved Myopic Sphere at 6 months Post-op.

1.5

1

0.5

0 Achieved

Post-op (D) Post-op -0.5

-1

-1.5 -16 -14 -12 -10 -8 -6 -4 -2 0 Pre-op (D)

315 APPENDIX XXc: Histogram of residual myopic spherical errors at 12 months post-op.

Attempted vs Achieved Myopic Sphere at 12 months Post-op.

1.5

1

0.5

0 Achieved

-0.5 Post-op (D) Post-op

-1

-1.5 -16 -14 -12 -10 -8 -6 -4 -2 0 Pre-op (D)

○ indicates one subject with a slightly larger residual sphere: patient 154 with pre-op (R) sphere -11.00D; at 12 months post-op. it has regressed to -1.25D. There was no more room in her corneal pachymetry to allow further enhancement, therefore glasses prescription has been given.

316 APPENDIX XXd: Histogram of residual myopic spherical errors at 24 months post-op.

Attempted vs Achieved Myopic Sphere at 24 months Post-op. 1.5 1 0.5 0 -0.5 -1 -1.5 -2 -2.5 Achieved -3 -3.5 -4 Post-op(D) -4.5 -5 -5.5 -6 -6.5 -7 -16 -14 -12 -10 -8 -6 -4 -2 0 Pre-op (D)

○ indicates two subjects with an unusually large residual sphere: subject 108 with pre-op sphere -8.80D & -7.70D right & left eye respectively, subject has decentred ablation, at 24 months post-op. both eyes have regressed to - 6.25D & -5.75D right & left eye respectively (note there are two data points for the two eyes of this subject). Subject wears hard contact lens post-operatively while waiting for further advancement of technology to enhance the results. Subject 47 with pre-op sphere of -6.05D, at 24 months it has regressed to -1.75D, originally it was planned for emmetropic correction, but post-operatively it became unintentional monovision, subject was at presbyopic age and decided to leave the result as it was.

317 APPENDIX XXIa: Histogram of residual minus cylindrical errors at 3 months post-op.

Attempted vs Achieved Minus Cylinder at 3 months Post-op.

0

-0.5

-1 Achieved Post-op. (D) Post-op. -1.5

-2 -8 -6 -4 -2 0 Pre-op (D)

○ indicates five subjects with a slightly larger residual cylinder: subject 175 with pre-op cylinder -2.25D, has had an enhancement of +1.25D, at 3 months post-enhancement it has regressed to -1.25D. Subject 186 with pre-op cylinder -0.50D had uncontrollable head movement during treatment which caused decentred ablation, had an enhancement of -1.75D, at 3 months post-enhancement it still remains at -1.25D. Subject 20 with pre-op cylinder -0.75D, at 3 months post-op. it has regressed to -1.25D. Subject 35 with pre-op cylinder -1.25D, at 3 months post- op. it was still -1.25D. Subject 46 with pre-op cylinder -6.00D, at 3 months post-op. it has regressed to -1.50D. It would be interesting to see what happens at later follow-ups.

318 APPENDIX XXIb: Histogram of residual minus cylindrical errors at 6 months post-op.

Attempted vs Achieved Minus Cylinder at 6 months Post-op.

0

-0.5

-1 Achieved Post-op.(D) -1.5

-2 -8 -6 -4 -2 0 Pre-op (D)

○ indicates four subjects with a slightly larger residual cylinder: subject 35 with pre-op cylinder -1.25D, at 6 months post-op. -1.25D persisted, enhancement was offered but subject has no problem visually, and leaves result as it was. Subject 147 with pre-op cylinder -0.75D, at 6 months post-op. it has regressed to -1.25D, subject is happy with result, therefore enhancement was not discussed. Subject 186, the same subject mentioned in Appendix XVIa, at 6 months post-enhancement it still remained at -1.25D. Subject 46, the same subject mentioned in Appendix XVIa, at 6 months post-op. it remained at -1.50D. It would be interesting to see where these subjects end up at later follow-ups.

319 APPENDIX XXIc: Histogram of residual minus cylindrical errors at 12 months post-op.

Attempted vs Achieved Minus Cylinder at 12 months Post-op.

0.5

0

-0.5

-1 Achieved -1.5 Post-op (D) Post-op -2

-2.5

-3 -8 -6 -4 -2 0 Pre-op (D)

○ indicates one subject with an unusually large residual cylinder: subject 74 with pre-op cylinder -0.75D, 12 months post-op. it has regressed to -2.50D, also this subject has gross punctuate epithelial keratitis, therefore, the entire post-operative management has been devoted to alleviating the dry eyes problem, and no enhancement was discussed. It would be interesting to see what happens to this subject at the end stage of the follow-up.

320 APPENDIX XXId: Histogram of residual minus cylindrical errors at 24 months post-op.

Attempted vs Achieved Minus Cylinder at 24 months Post-op.

0

-0.5

-1 Achieved -1.5 Post-op (D) Post-op

-2

-2.5 -8 -6 -4 -2 0 Pre-op (D)

○ indicates four subjects with a slightly larger residual cylinder: subject 20, the same subject mentioned in Appendix XVIa, at 24 months post-op. it remained at -1.25D. Subject 119 with pre-op cylinder -0.25D, at 24 months post-op. it regressed to -1.25D, subject was happy with result, therefore enhancement was not discussed . Subject 154, the same subject mentioned in Appendix XVb regarding the right residual myopic sphere, this time it involves the right minus cylinder with pre-op cylinder -2.00D, at 24 months post-op. it remains at -1.25D, there is no more room in her corneal pachymetry to allow further enhancement, therefore, glasses prescription has been given. Subject 46, the same subject mentioned in Appendices XVIa & b has now regressed to -2.25D.

321 APPENDIX XXIIa: Histogram of residual hyperopic spherical errors at 3 months post- op.

Attempted vs Achieved Hyperopic Sphere at 3 months Post-op.

2 1.5 1 0.5 0 Achieved -0.5

Post-op (D) Post-op -1 -1.5 -2 -2.5 0 2 4 6 8 Pre-op (D)

○ indicates four subjects with larger residual sphere. Subject 3 with pre-op sphere +3.60D, originally was intended for emmetropic correction, but post-operatively became monovision unintentionally, at 3 months post- op. it was overcorrected by -2.00D, subject was happy to leave result as it was. Subject 73 with pre-op sphere +5.20D, originally was intended for emmetropic correction, had two enhancements, at 3 months post- enhancement this eye remained as monovision unintentionally by -2.00D. Subject 14 with pre-op sphere +5.78D, was originally intended for emmetropic correction but at 3 months post-op. it became unintentional multifocal and regressed to +1.75D, subject was happy to leave the result as it was. Subject 85 with pre-op sphere +5.95D, at 3 months post-op. it has regressed to +1.25D, subject had monocular diplopia, enhancement was discussed, but subject was at the presbyopic age and decided to leave result as it was. It would be interesting to see what happens to these subjects at the later follow-ups.

322 APPENDIX XXIIb: Histogram of residual hyperopic spherical errors at 6 months post- op.

Attempted vs Achieved Hyperopic Sphere at 6 months Post-op.

2 1.5 1 0.5 0 -0.5 Achieved -1 Post-op (D) Post-op -1.5 -2 -2.5 -3 0 1 2 3 4 5 6 7 Pre-op (D)

○ indicates six subjects with a larger residual sphere: subject 18 with pre-op sphere +5.58D, at 6 months post-op. it has regressed to +1.50D. Subject 73 the same subject mentioned in Appendix XVIIa, at 6 months post-op both right & left eyes remain at -2.00D. Subject 92 with pre-op sphere +5.10D, had second enhancement more than 2 years after the original procedure, at 6 months post-enhancement both right & left eyes were overcorrected by - 2.00D. Subject 104 with pre-op sphere +2.00D, was overcorrected by -1.50D. Subject 211 with pre-op sphere +0.65D, at 6 months post-op was overcorrected by -2.00D. Subject 56 with pre-op sphere +1.75D was overcorrected by -2.75D. It would be interesting to see what happen to these subjects at the later follow-ups.

323 APPENDIX XXIIc: Histogram of residual hyperopic spherical errors at 12 months post- op.

Attempted vs Achieved Hyperopic Sphere at 12 months Post-op.

3 2.5 2 1.5 1 0.5 Achieved 0

Post-op (D) Post-op -0.5 -1 -1.5 -2 -2.5 0 2 4 6 8 Pre-op (D)

○ indicates four subjects with a larger residual sphere. Subject 180 with pre-op sphere +2.87D, at 12 months post- op was overcorrected by -1.25D. Subject 3 the same subject mentioned in Appendix XVIIa remained at -2.00D at 12 months post-op. Subject 92, the same subject mentioned in Appendix XVIIb remained overcorrected by - 1.75D at 12 months post-op. Subject 200 with pre-op sphere +3.65D, at 3 months it was under-corrected by +1.00D, at 6 months it was over-corrected by -1.00D, at 12 months it has regressed to +2.75D. It would be interesting to see what happens at 24 months follow-up.

324 APPENDIX XXIId: Histogram of residual hyperopic spherical errors at 24 months post- op.

Attempted vs Achieved Hyperopic Sphere at 24 months Post-op.

3

2.5

2

1.5 1 Achieved 0.5

Post-op (D) Post-op 0

-0.5

-1

-1.5 0 1 2 3 4 5 6 7 Pre-op (D)

○ indicates three subjects with larger residual sphere. Subject 57 with pre-op sphere +2.34D, at 24 months post- op it was overcorrected by -1.25D. Subject 180, the same subject mentioned in Appendix XVIIc, remained at - 1.25D in 24 months post-op. Subject 200, the same subject mentioned in Appendix XVIIc, at 24 months post-op. it remained under-corrected by +2.75D.

325 APPENDIX XXIIIa: Histogram of residual plus cylindrical errors at 3 months post-op. Attempted vs. Achieved Plus Cylinder at 3 months Post -op.

1.5

1

Achieved

Post-op (D) 0.5

0 0 2 4 6 Pre -op (D)

○ indicates one subject with a slightly larger residual sphere: subject 14 with pre-op refraction of +5.78D sphere and +0.75D cylinder, at 3 months the cylinder component was at +1.25D. It would be interesting to see what happens at later follow-ups.

326 APPENDIX XXIIIb: Histogram of residual plus cylindrical errors at 6 months post-op.

Attempted vs Achieved Plus Cylinder at 6 months Post-op.

1.5

1

Achieved

Post-op (D) Post-op 0.5

0 0 2 4 6 Pre-op (D)

327 APPENDIX XXIIIc: Histogram of residual plus cylindrical errors at 12 months post-op.

Attemped vs Achieved Plus Cylinder at 12 months Post-op.

1.5

1

Achieved

Post-op (D) Post-op 0.5

0 0 2 4 6 Pre-op (D)

○ There was one subject with a slightly larger residual cylinder: subject 161 with pre-op cylinder +1.25D, at 12 months it has regressed to +1.25D. It would be interesting to see what happens at 24 months post-op follow-up.

328 APPENDIX XXIIId: Histogram of residual plus cylindrical errors at 24 months post-op.

Attempted vs Achieved Plus Cylinder at 24 months Post-op.

2

1.5

1 Achieved

Post-op (D) Post-op 0.5

0 0 2 4 6 Pre-op(D)

○ indicates one subject with slightly larger residual sphere: subject 153 with pre-op refraction of +4.95D and +0.5D cylinder, had one enhancement to refine the under-corrected cylinder at 1.5 years after the initial procedure, at 24 months post-enhancement the cylindrical component was still at +1.50D. There was no further treatment plan.

329 APPENDIX XXIV: Clinical details of subjects who rated their unaided distance vision 5 out of 10 (Question 7a), pp. 185.

Scales Patient 3 months 6 12 months 24 months Comments rating I.D. months 5 76 Subject was - As in 3 - the rest of -6.50D, pre-op months the BCVA was questionnaire 6/4.5-1, dropped rated to 6/6-1 positively 5 87 Subject had As at 3 - - Only had 3 & monovision months 6 months correction, follow-ups. although p/op UCVA were 6/6 & N4.5, but was unable to adapt to monovision 5 111 Subject had - P/op UCVA P/op UCVA Subject gave monovision were 6/7.5 & were 6/9-1 & higher rating correction, p/op N4.5, (R) N4.5, had (R) (7) at 12 UCVA were enhancement enhancement months, but 6/4.5 & N4.5 was after almost 3 did not return discussed yrs p/op, day questionnaire subject 1 post- post- elected not to enhancement enhancement proceed was 6/4.5 5 135 Subject had - P/op UCVA - Subject gave monovision were 6/4.5 & higher rating correction, p/op N8, still had (8) at 12 UCVA were problem at months 6/7.5 & N6, had night and problem with close work fine close work. 5 151 Subject had As at 3 P/op UCVA P/op UCVA Subject gave monovision months were 6/7.5 & were 6/6 & higher rating correction, p/op N4.5, had N4.5, still had (7) at 24 UCVA were 6/6 depth depth months

330 & N4.5, has perception perception night vision problem problem problem. 5 154 Subject was - - P/op UCVA P/op UCVA 11.0D pre-op., were 6/12 & were 6/10 & had (L) 6/9, subject 6/6 enhancement, requested p/op UCVA were another 6/10 & 6/9, lost enhancement, > 2 lines BCVA. but cornea was too thin to do so 5 177 Subject had - - P/op UCVA Subject gave monovision were N5 & higher rating correction, p/op 6/6, still had (7) at 24 UCVA were N5 to wear months & 6/9, but was reading unable to adapt glass. to monovision 5 214 Subject was P/op P/op UCVA P/op UCVA Subject gave -6.0D pre-op., UCVA were B/L 6/6, were B/L 6/9, higher rating had (L) were 6/6 had poorer still had (7) & (8) at enhancement, & 6/4.5 vision in dim poorer vision 12 & 24 P/op UCVA lighting or at in dim months were B/L 6/6 night lighting or at respectively night 5 161 Subject was As at 3 P/op UCVA P/op UCVA Subject +4.0D pre-op., months were 6/9 & were 6/7.5 & continued to P/op UCVA 6/24, had B/L 6/9, still had have were B/L 6/6, punctum plus dry eyes fluctuation of had severe dry insertion problem vision due to eyes. dry eyes 5 18 Subject was As at 3 P/op UCVA P/op UCVA Subject gave +5.0D pre-op., months were 6/9 & were 6/9 & higher rating P/op UCVA 6/6 6/7.5 (7) at 3 & 12 were 6/9 & 6/7.5 months (R)enhancement

331 was discussed subject elected not to proceed 5 57 Subject had P/op UCVA As in 12 monovision were 6/9 & months, still correction, had N5, still unable to (L) unable to adapt to enhancement, adapt to monovision p/op UCVA were monovision 6/6 & N4.5, but unable to adapt to monovision 5 124 Subject had As in 3 P/op UCVA monovision months were N5 & correction, p/op 6/12, still UCVA were unable to N4.5 & 6/6, but adapt to unable to adapt monovision to monovision

332 APPENDIX XXV: Clinical details of subjects who rated their vision worse post- operatively in their ability to perform physical activities (Question 8a), pp. 192-3.

Scales Subject 3 months 6 months 12 months 24 months Comments rating I.D. Worse 18 Lost 1 line - Lost 1 line As in 12 Enhancement (2/5) BCVA, BCVA, gave months was enhancement rating 5/5 discussed 2x, was discussed, but decided but decided not not to to proceed proceed Worse 74 No lost BCVA, No lost BCVA, - Lost 3 lines (2/5) had severe dry had severe BCVA, the eyes dry eyes UCVA was 6/24 compared to 6/6 pre-op. BCVA, still having dry eyes problem

333 APPENDIX XXVI: Clinical details of subjects who rated their vision worse post- operatively in their ability to perform social/recreational activities (Question 8b), pp. 194-5.

Scales Subject 3 months 6 months 12 months 24 months Comments rating I.D. Worse 18 as in Lost 1 line - Lost 1 line Lost 1 line Enhancement (2/5) question BCVA, BCVA, rating BCVA, rating was 8a enhancement increased to increased to 3/5 discussed 2x, was discussed, 4/5 “better” “no change” but decided but decided not not to to proceed proceed Worse 58 (L) was treated - As at 3 months - (2/5) for monovision. Had an enhancement, could read N6 Worse 203 Had (R) treated As at 3 months As at 3 months As at 3 months (2/5) for emmetropia, lost 1 line BCVA. (L) treated for monovision, could read N5. Unable to adapt to monovision

334 APPENDIX XXVII: Clinical details of subjects who rated their vision worse post- operatively in their ability to perform home activities (Question 8c), pp. 196-7.

Scales Subject 3 months 6 months 12 months 24 months Comments rating I.D. Worse 18 as in Lost 1 line - Lost 1 line Lost 1 line Enhancement (2/5) question BCVA, BCVA, rating BCVA, gave was 8b enhancement increased to rating of 3/5 “no discussed 2x, was discussed, 4/5 “better” change” but decided but decided not not to proceed to proceed Worse 74 as in had severe dry Still had - Lost 3 lines (2/5) question eyes severe dry BCVA, the 8a eyes UCVA was 6/24 compared to 6/6 pre-op., still had dry eyes Worse 87 Had (R) treated - As at 3 months - (2/5) for emmetropic, lost 1 line BCVA. (L) treated for monovision, could read N5. Unable to adapt to monovision Worse 108 (R) Lost 2 lines - Lost 1.5 lines Subject Subject had (2/5) BCVA, (L) had BCVA, UCVA returned to severe enhancement, was 6/15 wearing hard decentred no loss of line compared to contact lenses ablation, BCVA, but 6/6 pre-op. with scrip of (R) required UCVA was 6/20 BCVA -6.25 customized compared to 6/6 (L) -5.75 to enhancement, pre-op. BCVA achieved 6/6 which is unavailable Worse 133 (R) treated for - - Optom. didn’t Subject still (2/5) monovision, test near V.A. unable to could read N8. (L) still lost 3 adapt to (L) treated for lines BCVA. monovision,

335 emmetropic, lost Unable to adapt avoids driving 3 lines BCVA. to monovision, at night, said Unable to adapt but rating still needs to to monovision increased to 4/5 wear readers “better”

336 APPENDIX XXVIII: Clinical details of subjects who rated their vision worse post- operatively in their ability to perform work activities (Question 8d), pp. 198-9.

Scales Subject 3 months 6 months 12 months 24 months Comments rating I.D. Worse 18 as Lost 1 line - Lost 1 line Lost 1 line Enhancement (2/5) above BCVA, BCVA, rating BCVA, rating was enhancement increased to increased to 3/5 discussed 2x was discussed, 4/5 “better” “no change” decided not to but decided not proceed to proceed Worse 41 (R) No loss of Only (2/5) BCVA, (L) lost completed 3 0.5 lines months BCVA., subject subject was presbyopic satisfaction opted B/L questionnaire emmetropic, c/o required readers Worse 53 Had (R) Only (2/5) enhancement, completed 3 (L) lost 2 lines months BCVA. Having subject problems with satisfaction reading and questionnaire computer Worse 58 as in (L) treated for Still could read Only (2/5) question monovision. N6, rating completed 3, 8b Had an increased to & 12 months enhancement, 3/5, still unable subject could read N6 to adapt to satisfaction monovision questionnaire Worse 62 Had (R) treated No change in No change in (2/5) for emmetropia, V.A., still c/o V.A., still c/o no lost BCVA. occas. blur, occas. blur, (L) treated for unable to unable to adapt monovision, c/o adapt to to monovision

337 occas. blur, monovision unable to adapt to monovision Worse 74 as in No lost BCVA, No change in Lost 3 lines (2/5) question had severe dry V.A., still had BCVA, the 8a, & c eyes severe dry UCVA was 6/24 eyes compared to 6/6 pre-op., still treating the dry eyes problem Worse 87 Had (R) treated No change in (2/5) for emmetropic, V.A., lost 1 line still unable to BCVA. (L) adapt to treated for monovision monovision, could read N5. Unable to adapt to monovision Worse 107 Had (R) No change in (2/5) enhanced. V.A., still c/o Subject was “decline in near presbyopic, vision” opted B/L emmetropic correction, c/o “decline in near vision” Worse 108 (R) Lost 2 lines (R) Lost 2 lines By this time Subject has (2/5) BCVA, (L) has BCVA, (L) had subject has severe had an an returned to decentred enhancement, enhancement, wearing hard ablation, no lost BCVA, lost 1.5 line contact lenses requires but UCVA was BCVA, but with scrip of (R) customized 6/20 compared UCVA was -6.25 enhancement, to 6/6 pre-op. 6/15 compared (L) -5.75 to which

338 BCVA to 6/6 pre-op. achieved 6/6 currently is BCVA unavailable Worse 118 No lost BCVA, No change in (2/5) c/o blur with V.A., did not c/o computer symptom Worse 160 Had B/L V.A. (2/5) enhancement, improved, no lost 3 lines line lost BCVA BCVA Worse 214 Had (L) V.A. No change in Lost 5 lines (2/5) enhancement. improved (R) V.A., (R) dry, BCVA B/L, (R) lost 7 lines lost 3 lines rating rating dropped (L) lost 3 lines (L) no lost increased to back to 2/5 BCVA BCVA 3/5 “no change” Worse 216 Had (R) treated V.A. improved, (2/5) for emmetropic, no lost BCVA, lost 3 lines could still read BCVA. (L) N5, rating treated for increased to monovision, 5/5 “much could read N6, improved” not adapt to monovision

339 APPENDIX XXIX: Clinical details of subjects who reported they wore glasses for distance/night driving (Question 9), pp. 201-2.

Category Subject 3 months 6 months 12 months 24 months Comments I.D. Need gls 31 Had (R) treated No change in for for emmetropic, V.A., unable dist/night no lost BCVA, to adapt to driving (L) treated for monovision (3) monovision, could read N4.5 Need gls 69 Had (L) (L) V.A. for enhancement, improved, still dist/night (L) lost 1 line needed gls. for driving BCVA night driving (3) Need gls 74 as in No lost BCVA, No change in Lost 3 lines for question had severe dry V.A., still had BCVA, the dist/night 8a, & c eyes severe dry UCVA was 6/24 driving eyes compared to (3) 6/6 pre-op., still treating the dry eyes problem Need gls 151 Had (R) treated No change in No change in for for emmetropic, V.A., unable to V.A., unable to dist/night lost 2.5 lines adapt to adapt to driving BCVA, (L) monovision, monovision, still (3) treated for needed gls for needed gls for monovision, driving driving could read N4.5 Need gls 154 Subject was (R) (L) lost 1 line B/L V.A. for -11 & (L) -12 BCVA, post-op improved, but dist/night pre-op., had (L) UCVA was (R) UCVA was driving enhancement, (R)6/12, (L)6/9, still 6/10, thus (3) (R & L) lost 1 enhancement needed gls. for line BCVA was discussed, night driving but no room to do so

340 Need gls 193 Subject was -10 Similar V.A. Similar V.A. for B/L pre-op., had dist/night B/L driving enhancement, (3) (L) lost 1 line BCVA, Need gls 207 Subject was (R) No change in for -9.5 & (L)-13 visual acuity, dist/night pre-op., (R) still needed gls. driving treated for for driving (3) monovision, could read N5, (L) treated for emmetropia, had an enhancement, unable to adapt to monovision

341 APPENDIX XXX: Clinical details of subjects who were expected to require glasses for near/close work (Question 9), pp. 201-2.

Category 3 months 6 months 12 months 24 months Need gls for 21 out of 41 13 out of 25 12 out of 24 8 out of 22 near/close work subjects were > subjects were > subjects were > subjects were > (4) 40 years of age, 40 years of age, 40 years of age, 40 years of age, opted to have B/L opted to have B/L opted to have B/L opted to have B/L emmetropic emmetropic emmetropic emmetropic treatment. treatment. treatment. One treatment. subject was 27 years of age reported that he needs readers, was -8.0D pre-op., post-op. UCVA was 6/6 c/o (R) dry eyes

342 APPENDIX XXXI: Clinical details of subjects who were not expected to require glasses for near/close work (Question 9), pp. 201-2.

Scales rating 3 months 6 months 12 months 24 months Need gls for 16 out of 41 9 out of 25 8 out of 24 6 out of 22 near/close work subjects were > subjects were > subjects were > subjects were > (4) 40 years of age, 40 years of age, 40 years of age, 40 years of age, opted to have opted to have opted to have opted to have monovision monovision monovision monovision treatment. treatment. treatment. treatment.

343 APPENDIX XXXII: Clinical details of subjects who rated the surgery to be “moderately unsuccessful” and “very unsuccessful” (Question 15), pp. 208.

Subject I.D. 3 months 6 months 12 months 24 months 58 as Unable to adapt At the 4 th survey, mentioned in to monovision, responded “Very question 8, 9, rated unsuccessful” (1) 11, & 17 “moderately unsuccessful” (2) 18 as Lost 1 line BCVA, mentioned in decided against question 8 enhancement, rated “moderately unsuccessful” (2) 108 as Has severe decentred mentioned in ablation, waiting for question 8 & customized 17 enhancement, rated “moderately unsuccessful” (2) 164 as No lost BCVA, but mentioned in said “vision is not question 17 as sharp”, rated “moderately unsuccessful” (2) 161 as Has dry eyes, fluctuate mentioned in V.A. (R) lost 3 (L) lost 2 question 17 lines BCVA, rated “moderately unsuccessful” (2)

344 APPENDIX XXXIII: Clinical details of subjects who rated the surgery outcomes as partially meeting their expectations (Question 16), pp. 209.

Subject I.D. Clinical details 1 (R) treated for emmetropia, (L) treated for monovision, had small (R) myopic under- correction, discussed (R) enhancement, but subject did not proceed. At 2 nd , 3 rd & 4 th survey subject indicated that the surgery did meet expectations 4 Had B/L myopes emmetropic correction, post-op UCVA = 6/4.5 = pre-op BCVA, no residual refractive error, only completed 3 months survey and indicated that “there is imbalance of eye strength” 9 (R) treated for monovision, (L) treated for emmetropia, could see N4.5 and 6/6 unaided post-op., no lost BCVA, only completed 3 months survey and indicated that “eyes are sore at night” 11 Had (R) hyperopes emmetropic correction, no treatment in (L) with history of iritis, no lost BCVA, by 12 months post-op UCVA dropped to 6/7.5 & 6/9 by 24 months post-op., c/o of problem with reading, by that stage the subject was presbyopic. 36 Had B/L -4.0D emmetropic correction, (R) gained 1 line BCVA, (L) had fine wrinkles, by 2nd survey c/o fluctuate V.A., by 4 th survey c/o dry eyes, lost 3 lines BCVA, UCVA dropped to 6/7.5, subject rating dropped to “partially met expectations” at 3 rd & 4 th survey. 57 (R) treated for emmetropia, (L) treated for monovision, unable to adapt to monovision, required distance glasses. 65 Had B/L emmetropic correction, no lost BCVA, c/o reading problem, subject was presbyopic. 71 Had B/L -11.0D emmetropic correction, no lost BCVA, c/o night driving problem at 12 months post-op, by 24 months no change in V.A. & rated “result met expectations”. 77 Had B/L -10.0D emmetropic correction, had (L) flap clean & refloat, had B/L diffuse lamellar keratitis, lost 3 lines BCVA, c/o glare and dry eyes intermittently. 83 Unable to adapt to monovision, had enhancement to remove it 82 Unable to adapt to monovision, had enhancement to remove it 85 Under-corrected hyperopes 97 Had (L) monovision correction, could read N6, unable to adapt to monovision 141 Had B/L -5.0D & -7.0D emmetropic correction, no lost BCVA but (L) post-op UCVA was 6/7.5 due to -0.75D residual cylinder, c/o slight glare & blur. 153 (R) treated for monovision, (L) treated for +5.0D emmetropic, had (L) enhancement, by the 4 th survey lost 3 lines BCVA, post-op UCVA was 6/18, N8, but required readers. 159 Had B/L emmetropic correction, no lost BCVA but post-op UCVA was 6/6 compared to

345 6/4.5 pre-op, c/o blur at distance & dry eyes, required distance glasses. 165 (R) treated for monovision, (L) treated for emmetropia, at 1 st survey resulted in unintended emmetropia, happy to leave as is, at 3 rd survey decided to enhance the (R) for monovision, could see N4.5 and 6/4.5 unaided but still unable to adapt to monovision. 167 (R) treated for monovision, (L) treated for emmetropic, could read N4.5 & 6/4.5, stated that she wears readers, but result “met expectations”, at the 4 th survey rating dropped to “partially met expectations”. 174 (R) treated for emmetropic, (L) treated for monovision, could see 6/6 & N4.5, unable to adapt to monovision, one year post-op vision was similar, subject rated “result exceeded expectation” 177 (R) treated for monovision, (L) treated for emmetropic, had (L) enhancement, unable to adapt to monovision, by the 4 th survey subject rated “result met expectation” 186 Decentred ablation due to subject’s head & eyes movement 200 Under-corrected hyperopes with some lenticular opacity 212 (R) treated for emmetropia, (L) treated for monovision, immediately post-op subject had B/L epithelial defect, this caused discomfort & affected the vision, at the 1 st survey subject could see 6/6 & N4.5, but unable to adapt to monovision.

346 APPENDIX XXXIV: Clinical details of subjects who stated they were “undecided” in response to question, “Now that you have undergone the surgery, knowing what you know now, would you still have LASIK?” (Question 17), pp. 210.

Scales Subject 3 months 6 months 12 months 24 months Comments rating I.D. Undecided 62 as Had (R) Still said No clinical (3) mentioned treated for “Too early to data, but in Q8d emmetropia, tell” completed the no lost BCVA, questionnaire (L) left for indicated “yes” monovision, (1) said “Too early to tell” Undecided 164 Had (R) No change in (3) treated for V.A., but said emmetropia, “vision is not (L) treated for as sharp”, monovision, and response No lost BCVA, in 3 rd survey response in indicated the 1 st survey “undecided” indicated “yes” Undecided 166 Had (R) No clinical No change in The (3) treated for data, but V.A., symptom monovision, completed completed the may be could read N5, the questionnaire, caused by (L) treated for questionnaire indicated “not inability to emmetropia, indicated sure” (3), c/o adapt to the no lost BCVA, “yes” (1) blur at night monovision said “not sure” Undecided 161 Had B/L Fluctuate Still has dry (3) emmetropic to V.A. with dry eyes, treat +4.0D, eyes, (L) lost Fluctuate V.A. (R) lost 3 line 3 lines BCVA, (R) lost 3 (L) BCVA, rated but UCVA lost 2 lines “yes” was 6/15 BCVA, compared to response to

347 6/6 at 3 the months post- questionnaire op., still indicated indicated “maybe” “yes” Undecided 59 Had B/L No change in No clinical (3) emmetropic, V.A. data, but had difficulty completed the with fixation, questionnaire, (L) flap clean indicated & re-float, no “unsure for the lost BCVA, same reasons” said “unsure (3) for these reasons” No (4) Subject 58 as mentioned in questions 8, 9 & 11 unable to adapt to monovision Questionable Subject 74 as mentioned in question 8, has severe dry eyes, lost 3 lines BCVA, UCVA was (5) 6/24 compared to 6/6 pre-op Questionable Subject 87 as mentioned in question 8, (R) lost 1 line BCVA, could read N5, but unable to (5) adapt to monovision Questionable Subject 108 as mentioned in question 8, has severe decentred ablation, waiting for (5) customized enhancement Questionable Subject 183 had B/L emmetropic correction, (R) was -6.0D pre-op., had (R) enhancement, no (5) lost BCVA, at 1 st survey said “absolutely”, at 2 nd survey said “have to think very hard about it”

348 APPENDIX XXXV: Clinical details of subjects who rated themselves “Somewhat less satisfied” and “Less satisfied” in response to “Are you more satisfied or less satisfied with the vision you have now compared to the vision you had previously with glasses and/or contact lenses?” (Question 20), pp. 213-5.

Scales Subject Comments rating I.D. Less Subject 58 as mentioned in question 8, 9, 11, 15, 16, 17 & 18, unable to adapt to satisfied (1) monovision Subject 87 as mentioned in question 8, 16 & 17, unable to adapt to monovision Subject 97 as mentioned in question 16, unable to adapt to monovision Subject 108 as mentioned in question 8, 11, 15, 16 & 17, had severe decentred ablation, B/L lost 2 lines BCVA, post-op UCVA was so poor subject had to return to hard C.L. with scrip of -6.0D while waiting for customized enhancement. Subject 214 as mentioned in question 8, lost 5 lines BCVA B/L, by 3 rd & 4 th survey subject’s rating increase to “somewhat less satisfied” (2). Subject 161 as mentioned in question 15, 16 & 17, (R) lost 3 (L) lost 2 lines BCVA, fluctuate V.A. with dry eyes, by 4 th survey subject’s rating increased to “somewhat less satisfied” (2). Somewhat Subject 18 as mentioned in question 8, 15 & 16, lost 1 line BCVA, refused enhancement. less satisfied (2) Subject 36 as mentioned in question 16, (L) had fine wrinkles, c/o fluctuate V.A., dry eyes, lost 3 lines BCVA, post-op UCVA was 6/7.5 compared to 6/4.5 pre-op. Subject 54 had B/L -4.0 & -5.0D emmetropic correction, had B/L enhancement, c/o poorer vision at night & when tired, by 4 th survey subject’s rating increased to “somewhat more satisfied” (4). Subject 62 as mentioned in question 8 & 17, unable to adapt to monovision Subject 63 had B/L -8.0 & -5.0D emmetropic correction, no lost BCVA, c/o poorer night vision, by 4 th survey subject’s rating increased to “much more satisfied” (5). Subject 71 as mentioned in question 16, had B/L -11.0D emmetropic correction, c/o night driving problem. Subject 74 as mentioned in question 8, 9, 16 & 17, lost 3 lines BCVA, post-op UCVA dropped to 6/24 compared to 6/6 pre-op, had severe dry eyes by the 4 th survey and was treated for dry eyes, unable to obtain stable refraction for enhancement. Subject 96 had B/L -4.0 & -5.0D emmetropic correction, no lost BCVA but by 24 months post-op UCVA dropped to 6/7.5 compared to 6/4.5 at 3 months post-op. Subject 124 had (R) monovision (L) emmetropic correction, could see N4.5 & 6/6 UCVA

349 post-op, at 4 th survey (L) UCVA dropped to 6/12, lost 1 line BCVA, c/o blur at distance. Subject 146 had B/L hyperopes emmetropic correction, had dry eyes, had B/L punctum plugs insertion, by the 3 rd survey post-op UCVA were 6/4.5, subject’s rating increased to “much more satisfied” (5). Subject 164 as mentioned in question 15 & 17, unable to adapt to monovision, by the 3 rd survey subject’s rating decreased to “less satisfied” (1). Subject 186 as mentioned in question 16, had decentred ablation due to subject’s head & eyes movement.

350 APPENDIX XXXVI: subjects’ satisfaction scores for those who had unintended results and/or required enhancement in question 20, pp. 213-5.

No. of subject & Survey 1 Survey 2 Survey 3 Survey 4 Category 4 subjects had Subject 3 & 47 Subject 14 rated Subject 3 rated No data on any unintended rated “5”. Subject “4”. Subject 175 “5”. No data on of these monovision 14 & 175 rated “4”. rated “5”. No data other subjects. subjects. on other subjects. 2 subjects had Subject 179 rated No data on any of Subject 6 rated Subject 179 unintended “4”. No data on these subjects. “3”. rated “3”. No emmetropia other subjects Subject 179 rated data on other “4”. subject. 3 subjects had Subject 82 rated Subject 82 rated Subject 83 rated Subject 82 enhancement to “4”. Subject 83 & “4”. No data on “3”. Subject 191 rated “3”. No remove monovision 191 rated “5”. other subjects rated “5”. No data data on other on other subject. subjects.

Note: The Likert scale in question 20 is such that 1 = less satisfied, 2 = somewhat less satisfied, 3 = about the same, 4 = somewhat satisfied, and 5 = more than somewhat satisfied.

351 APPENDIX XXXVII: Result of research question 18, no significant differences in subjects’ responses to the questionnaire between subjects who returned for more than one survey and those who returned for only one survey, p. 218.

Variables in questionnaire Statistical analysis outcomes 6a “Pain” t = 0.14, p = 0.90 (p > 0.01, not significant) 6b “Irritation” t = -1.2, p = 0.24 (p > 0.01, not significant) 6c “Glare” t = 0.77, p = 0.44 (p > 0.01, not significant) 6d “Dry eye” t = -0.8, p = 0.40 (p > 0.01, not significant) 7a “Distance vision” t = -1.0, p = 0.32 (p > 0.01, not significant) 7b “Near vision” t = 0.34, p = 0.73 (p > 0.01, not significant) 7c “Daytime driving” t = 0.35, p = 0.73 (p > 0.01, not significant) 7d “Night driving” t = -0.08, p = 0.94 (p > 0.01, not significant) 8a “Physical activities” t = -0.65, p = 0.52 (p > 0.01, not significant) 8b “Social or recreational activities” t = -1.4, p = 0.16 (p > 0.01, not significant) 8c “Home activities” t = -0.46, p = 0.65 (p > 0.01, not significant) 8d “Work activities” t = -0.82, p = 0.41 (p > 0.01, not significant) 11 “Overall quality of life” t = -0.16, p = 0.87 (p > 0.01, not significant) 12 “Info given prior to surgery” t = 1.2, p = 0.24 (p > 0.01, not significant) 13 “Info given immediately post-op t = 0.06, p = 0.96 (p > 0.01, not significant) 14 “Info regarding post-op care” t = 1.65, p = 0.11 (p > 0.01, not significant) 15 “Success of surgery” t = -0.63, p = 0.53 (p > 0.01, not significant) 16 “Satisfaction relative to pre-op expectations” t = -0.08, p = 0.94 (p > 0.01, not significant) 20 “Subject satisfaction” t = -1.1, p = 0.26 (p > 0.01, not significant)

352 APPENDIX XXXVIIIa: Clinical details of subjects with > one diopter residual refractive errors and their satisfaction scores, pp. 221-2.

5 “much more 4 “somewhat 3 “about the 2 “somewhat 1 “less satisfied” more satisfied” same” less satisfied” satisfied” In Append. Subject 108 XXa In Append. Subject 154 XXc In Append. Subject 47 Subject 108 XXd In Append. Subject 46 Subject 20 & Subject 35 Subject 186 XXIa 175 In Append Subject 46 Subject 35 & Subject 186 XXIb 147 In Append. Subject 74 with pre-op cylinder of -0.75D; at 12 months post-op it had regressed XXIc to -2.50D, had gross punctuate epithelial keratitis, subject did not return the questionnaire, but rated 2 “somewhat less satisfied” at survey 1 & 2. In Append. Subject 119 Subject 46 XXId Subject 20 with pre-op cylinder of -0.75D, at 24 months post-op. it remained at - 1.25D, subject did not return the questionnaire, but rated 4 “somewhat more satisfied” at survey 1. Subject 154 with pre-op cylinder of -2.00D, at 24 months post-op. it remained at -1.25D, subject did not return the questionnaire, but rated 4 “somewhat more satisfied” at survey 1 and rated 5 “much more satisfied” at survey 2. In Append. Subject 3, 73 & Subject 14 XXIIa 85 In Append. Subject 57, 73, XXIIb 92, 104 & 211 Subject 18 with pre-op sphere +5.58D, at 6 months post-op. it had regressed to +1.50D, subject did not return the questionnaire, but rated 4 “somewhat more

353 satisfied” at survey 1. In Append. Subject 3, 92, XXIIc & 180 Subject 200 with pre-op sphere of +3.65D, at 12 months post-op. it had regressed to +2.75D, subject did not return the questionnaire, but rated 4 “somewhat more satisfied” at survey 1 & 2. In Append. Subject 57 Subject 180 XXIId Subject 200 as mentioned above, at 24 months post-op. it remained at +2.75D, subject did not return the questionnaire, but rated 4 “somewhat more satisfied” at survey 1 & 2. In Append. Subject 14 XXIIIa In Append. Subject 161 XXIIIc In Append. Subject 153 XXIIId

354 APPENDIX XXXVIIIb: Clinical details of subjects with > one diopter residual refractive errors and their individual circumstances, pp. 221-2.

There were four subjects who rated themselves “somewhat less satisfied” and “less satisfied”. Their clinical details were: Subject 108 had (R) -8.80/-2.50X30 (L) -7.70/-2.00X160 pre- operatively, had bilateral decentred ablation and consequently had been wearing hard contact lenses (R) -6.25 (L) -5.75, while waiting for customized ablation enhancement. Subject 186 had (R) -4.40/-0.50X175 (L) -5.93/-2.50X10 pre-operatively, had bilateral decentred ablation due to subject’s head movement, only returned for survey 1 and only had right refraction done (R) +0.50/-1.25X110, has been waiting for customized ablation enhancement. Subject 74 had residual cylinder of -2.50D, and gross punctuate epithelial keratitis. Subject 161 had (R)+3.73/+1.50X95 (L) 3.98/+1.25X85 pre-operatively, had persistent severe dry eyes with fluctuation of vision, the estimated refractive errors were (R)+0.25/-0.75X180 (L) +0.25/- 0.75X180 at survey 4.

355 APPENDIX XXXIX: Result of research question 24, variables which had significant association between satisfied and dissatisfied subjects at four surveys, pp. 223-6.

Questions/survey Recode 20 N Mean S.D. t p Amount of glare Satisfied 98 0.83 1.09 -2.67 0.009 at survey 3 Dissatisfied 25 1.52 1.39 Distance vision Satisfied 168 9.13 1.27 2.53 0.01 at survey 1 Dissatisfied 47 8.57 1.47 at survey 2 Satisfied 70 9.26 1.10 2.61 0.01 Dissatisfied 25 6.92 2.33 Social/recreational Satisfied 168 4.47 0.82 2.53 0.01 activities at survey 1 Dissatisfied 47 4.13 0.82 at survey 4 Satisfied 97 4.56 0.72 3.31 0.01 Dissatisfied 24 3.96 1.04 Home activities Satisfied 168 4.37 0.82 3.37 0.001 at survey 1 Dissatisfied 47 3.83 1.0 at survey 2 Satisfied 70 4.40 0.73 3.17 0.003 Dissatisfied 30 3.73 1.05 at survey 3 Satisfied 98 4.58 0.67 3.47 0.001 Dissatisfied 25 4.0 1.0 at survey 4 Satisfied 95 4.41 0.72 4.72 < 0.001 Dissatisfied 24 3.58 0.93 Work activities Satisfied 165 4.32 0.89 3.32 0.002 at survey 1 Dissatisfied 46 3.72 1.13 at survey 2 Satisfied 67 4.30 0.94 3.21 0.002 Dissatisfied 30 3.60 1.10 at survey 3 Satisfied 97 4.47 0.79 3.0 0.006 Dissatisfied 25 3.76 1.13 at survey 4 Satisfied 94 4.31 0.90 4.80 < 0.001 Dissatisfied 24 3.30 1.04 Quality of life Satisfied 168 4.63 0.57 2.89 0.004 at survey 1 Dissatisfied 47 4.34 0.70 at survey 4 Satisfied 97 4.75 0.46 2.92 0.007 Dissatisfied 25 4.16 1.0 Success of surgery Satisfied 70 3.84 0.40 2.75 0.009 at survey 2 Dissatisfied 30 3.57 0.49 at survey 4 Satisfied 97 3.92 0.29 3.38 0.002 Dissatisfied 25 3.34 0.85 Surgery outcome Satisfied 168 3.80 0.97 5.04 < 0.001 met expectations Dissatisfied 46 3.11 0.77 at survey 1 at survey 2 Satisfied 70 3.84 0.97 4.53 < 0.001 Dissatisfied 30 2.93 0.78 at survey 3 Satisfied 98 3.80 0.94 3.45 0.001 Dissatisfied 25 3.10 0.86

356 at survey 4 Satisfied 97 3.97 0.90 4.24 < 0.001 Dissatisfied 25 3.12 0.88

357 APPENDIX XL: Result of research question 25, variables which had significant association between “glasses” and “no glasses” subjects at four surveys, pp. 226-8.

Questions/survey Recode 20 N Mean S.D. t p Near vision Glasses 165 9.0 1.41 6.84 < 0.001 at survey 1 No Glasses 50 6.24 2.73 at survey 2 Glasses 71 9.11 1.20 4.30 < 0.001 No Glasses 30 6.80 2.80 at survey 3 Glasses 92 8.80 1.73 4.70 < 0.001 No glasses 30 6.30 2.70 at survey 4 Glasses 90 9.0 1.82 5.40 < 0.001 No glasses 32 6.34 2.60 Night driving Glasses 90 8.44 1.77 2.71 0.008 at survey 4 No glasses 32 7.31 2.63 Quality of life Glasses 165 4.65 0.53 3.21 0.002 at survey 1 No glasses 50 4.30 0.76 Information given Glasses 165 4.70 0.58 2.88 0.005 prior to surgery No glasses 50 4.32 0.87 at survey 1 Surgery outcome Glasses 90 3.92 0.86 2.80 0.007 met expectations No glasses 33 3.40 1.12 at survey 4

358 APPENDIX XLI: Result of research question 28, variables which had significant association between “younger than” and “older than 40 years of age” subjects with variables in the questionnaire at 4 surveys, p. 230-1.

Questions/survey Recode 20 N Mean S.D. t p Near vision Younger 102 9.18 1.40 5.93 < 0.001 at survey 1 Older 114 7.61 2.40 at survey 2 Younger 47 9.43 0.93 5.22 < 0.001 Older 54 7.56 2.42 at survey 3 Younger 56 9.10 1.64 4.40 < 0.001 Older 67 7.46 2.44 at survey 4 Younger 50 9.28 1.74 4.29 < 0.001 Older 72 7.64 2.50 Quality of life Satisfied 102 4.72 0.50 3.61 < 0.001 at survey 1 Dissatisfied 114 4.43 0.66 Quality of life Younger 47 4.70 0.52 2.90 0.005 at survey 2 Older 54 4.30 0.83 Social/recreational Younger 102 4.55 0.70 2.60 0.01 activities at survey Older 114 4.26 0.91 1

359 APPENDIX XLII: Result of research question 36, logistic regression “variables in the equation”, pp. 238-40.

B S.E. Wald df Sig. Exp(B) Step Q16 .909 .214 18.074 1 .000 2.483 1(a) Constan -1.864 .714 6.812 1 .009 .155 t Step Q12 -.915 .345 7.049 1 .008 .401 2(b) Q16 1.132 .242 21.907 1 .000 3.101 Constan t 1.660 1.553 1.143 1 .285 5.261 Step Q8C .534 .214 6.258 1 .012 1.706 3(c) Q12 -1.107 .375 8.717 1 .003 .331 Q16 1.040 .247 17.786 1 .000 2.829 Constan .643 1.683 .146 1 .702 1.903 t a Variable(s) entered on step 1: Q16. b Variable(s) entered on step 2: Q12. c Variable(s) entered on step 3: Q8C.

360