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2-5-1982

Optometric management of the

Scott R. Walt Pacific University

Steven Meyers Pacific University

Recommended Citation Walt, Scott R. and Meyers, Steven, "Optometric management of the pterygium" (1982). College of Optometry. 650. https://commons.pacificu.edu/opt/650

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Abstract Optometric management of the pterygium

Degree Type Thesis

Degree Name Master of Science in Vision Science

Committee Chair Subject Categories Optometry

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tJ ~ l. s R

OPI'OMETRIC MANAGEMENT

OF THE

PI'ERYGIUM

by , Scott R. / Walt Steven Meyers~

• rv-. -- e)..tr _.h,J {r,:L~ .. [ l /

February 5, 1982 OPI'OMETRIC MANAGE1'1ENT OF THE PI'ERYGIUM

Researched and reported by Scott R. Walt and Steven Meyers

Fterygiums have been recognized and described for approximately 3000 years. 1 Although during this time a great deal of information has been acquired concerning the characteristics of pterygiums, there are still many questions about them that remain unanswered. Irt this paper we will discuss various aspects of pterygiums, the questions that are still unan- swered, and the role of the optometrist in caring for them.

Suruta, an Egyptian surgeon in 1000 B. C. described the occura.nce of 2 pterygiums as common in his time and he also described one of the oldest surgical procedures of them on record. Suruta believed pterygiums were due to a nutritional deficiency.J Aetius, a physician in Constantinople, described a surgical procedure for the removal of a pterygium in the fifth centuary B.c.3 Pterygiums were also described by Hippocrates in

460 B.C. and Galen in 131 A.D. As information has been gathered, a con- sistency in conditions has been noted.

Personal observations of both optometrists and opthalmologists have shown that pterygiums are very frequently seen in warm, dry, windy and dusty regions but less frequently in still, humid and warm regions of the south. People, such as ranchers and farmers, whose occupation causes them to be exposed repeatedly for long periods of time to these f:l:rst cond.i-- tions &re':i5een to have a higher incidence of pterygiums. A study of saw­ mill workers·, in particular, brought out some interesting information. A Page 2

25%_ &ge-adjusted prevalence rate was found in sawmill workers compared to a ?%'rate in the control group and the data indicated that the chance of developing a pterygium increased with the length of employment at the saw­ mill.3

Geographically speaking, pterygiums occur at an incidence of less than 1% in the population of peoples between the poles and 40° latitude. l"10re specifically, the so-called "pterygium belt" has been defined as that 0 • 4 area from 37° north latitude to 37 south latitude, This describes a strip of area which encircles the earth and is symmetrical with respect to the equator. This, of course, fits in well with the previously listed warm, dry, windy and dusty conditions. In order to obtain more information concerning the characteristics of those people with pterygiums, studies have· been conducted with specific people populations. For example, the Navajo Indians who live in north- eastern Arizona have been found to have a high incidence of pterygiums.

An inter~sting factor that goes along with this occurrance is that this area has a gr~ater ~~ount of ultraviolet light than in any other location in the United States.5 Eskimos have been found to have what would appear to be a surprisingly high rate of pterygiums considering that the previ- ously listed condition of a warm climate is for the most part not ful- filled. However, multiple r eflections from the snow are thought possibly to play an imprtant part in this, One source states the rate of incidence in this population to be 9%. 3 A study completed in Newfoundland reports that men over the age of forty have a 33% occurrence rate of pterygiums. j Page 3

The occupations of those with pterygiums were primarily woodsmen and fish- ermen.

A study was also completed in Israel which presents some statistics that tend to be difficult to explain. The most prominent fact that stands out concerns pterygium incidence in relation to occupation. Being an ag- ricultural country, we would typically expect a significantly higher in- cidence of pterygiums in those people working outdoors. However, it was found that those people who work indoors had 49% of the pterygiums and ' 6 outdoor workers had only 51%. This slight difference is in no way sig- nificant. Since the factors that apparently correlate with pterygium occurrence are only largely in efflct out of doors, there appears to be no obvious explanation for the findings of this study. A possible explan- ation for this discrepency is that the work hours are from very early morning until noon, similar to field workers in the United States. This schedule, therefore, allows workers to avoid harsh midday conditions which lead to pterygium development.

The physical location of pterygiums has also been observed in stud- ies. One such study has found that 91% of the people with pterygiums had them on the medial side and that 25% of the cases were bilateral.? The study in Israel, previously mentioned, found only four people out of 460

(0.87%) had exclusively temporal pterygiums. In addition, a pterygium was not found which extended beyond the center of the .6 An inter- esting and unique sidelight is that a statistically significant number

(to the .002 level) had left sided prevelance. Another study, however, Page 4 found a higher rate (2.4%) of temporal pterygiums and no difference in ' 8 occurrence between the right and left eyes. A finding widely agreed tipon was that a large percentage of temporal pterygiums seen are found in conjunction with a nasal pterygium.

Another factor widely agreed upon is that there is no significant difference in the rate of pterygium occurrence in males and females.

Only one study was specific enough to mention that 52% of the cases were female, which was not significant.?

The average age of those studied who had pterygiums was 44. Ftery- giums are rarely seen in people under twenty years of age, with an occur­ rence of only 0.14% in children under sixteen.6 The highest prevalancy = ~ rate, on the other hand, occurs at age fifty. 9 A decline can be observed in occurrence from then on, especially after age 70. It appears from longitudinal observations that pterygiums regress with senescence. How- ever, despite the facts which have been collected concerning age, no sig- nificant age~incidence relationship can be found. The exceptions to this are the extremes as in the very young or very old person. Studies which have been conducted within families have found pteryg- iums to be carried as a dominant trait with variable penetrance. The in- heri ted characteristics have been described as--varying sensi ti vi ty to ultraviotet light, prominence of the eye from the causing greater exposure (as seen in Polynesians), variation in the amount of lacrimal secretion and a variation in the blink rate.9 One study specifically 10 describes 19 year old twins. It was believed that few, if any, environ- Page5

mental factors had a significant role in the developement of their ptery-

· gium:s at this age. It was observed that the formation and developement

of the pterygiums were similar. Careful scrutinizing of the family tree

in this case suggested autosomal dominance with incomplete penetrance,

Another study was done on a specific population of people according

to their refractive status. Myopes living at the equator where conditions

were sunny, windy and 50% humidity were found to have an incidence of only

6.2%. 11 It is believed that the glasses worn by these people acted as a

protective barrier for the eyes, thus shielding them from the harsh envi-

ronmental factors. This possibility will be discussed to a greater extent

later in the paper,

Pingueculas are considered by some authorities to be a P-recursor to 12 pterygiums, so, for this reason, we will take .a brief look at them,

When observed through the , pingueculas are seen as avascu-

lar elevations of elastic tissue which are surrounded by conjunctival

blood vessels of normal size. These normal sized vessels may send extreme-

ly fine vessels into the elevation. An inflamed will have en-

gorged conjunctival blood vessels at the limbus and surrounding the less

vascular pinguecular elevation.

On the other hand, a rapidly growing primary pterygium can be describ-

ed as a vascular structure of blood vessels and loose fibrous connective

tissue which is covered by epithelium, The pterygial conjunctival stroma

is formed by the combination of masses of amorphous hyalin and fragmented collagen fibers to form granular basophilic material~3 Also seen at this Page 6 point are new blood vessels and an accumulation of large mononuclear connective tissue cells. Histologically, the strucv~ral modification of stromal protein creates pterygium angiogenesis factor (PAF) which is mitogenic to endothelial cells of conjunctival capillaries~] In the head of the pterygium, Bowman's membrane is replaced by the active proliferation of endothelial vascular buds. In front of these vascular arcades, a zone of edema can be found which extends into the stroma.2 This edematous area extends out ahead of the pterygium head, Also, at the head of the pterygium we can see lipoid degeneration of the cornea. This is part of a protective process of the eye which takes place to inhibit growth,

In contrast to the actively growing pterygium, there is no edema pre- ceeding the head of a stationary pterygium. other characteristics of a stationary pterygium are that the vascular channels are closed and there can be seen an increase in fibrous connective tissue.

Pterygiums which fall between the two previous categories, such as those which are slowly growing or extend laterally into only one third of the cornea, have blood vessels that go only as far down as Bowman',s layer,

However, the blood vessels of rapidly growing pterygiums extend into the stroma. The base of the pterygium is also broader. If these deep blood vessels are not removed, they will have a high probability of recurrence.

Unfortuneatly, no one specific grading system is being used univer- sally to describe pterygiums. A typical grading system describes a ptery­ giu~th two numbers. The first is a roman numeral which grades the de- Page 7

gree · o~ vascularity from I to V, I being minimal and V being maximal.

The ~econd number simply tells the amount of advancement onto the cornea in millimeters. A basic system like this allows us to form a good mental picture of what the pterygium being described looks like.

A table has been constructed categorizing pterygiums and describ- 14 ing those categories.

l Type I I Type II I Type I II l Progressive . I Mildly prog I Regressive 1------T------~------Recurrence I 88% : 65% l 4% I I I I I I I l I ------~------T------~------~I I I Age Of I I I recurrence I (40-92% I )'40-26% l I I I I I I I I I ------~------..,.----"T------... ------I I I Riecurr i ng l Larger l Same l Smaller S ze I I I I

A pterygium is rarely seen to cross the limbal area of a patient with arcus senilis!3 At this time we believe that the lipoid deposition

of arcus senilis inhibits growth as does corneal lipoid degeneration

previously mentioned. This fact correlates well with the finding that

few pterygiums are seen in the older generation, such as those seventy and above. We also need to take into account, however, that this age group usually spends a great .deal of time indoors.

-·Although the pterygium has been identified for thousands of years,

no definitive etiology has yet been established. The great deal of re-

search invested in the study of pterygiums through the years, however, . Page 8 has. produced an enormous variety of etiological theories, as well as meth.ods of treatment.

In 1804, Richter stated that a pterygium is always preceeded by a pinguecula.J Scarpa maintained in 1916 that the underlying cause is a chronic .) Schreiter, in 1872, postulated that the ptery­ gium is a neoplasm, a pOlypoid growth of the .3 In 1887,

Theobald suggested that fatigue of the m~ial and lateral recti were at least part of the etiology.J Fuchs wrote a very influential paper in

1891 in which he attempted to divide pterygiums into categories of sta- tionary or progressive, depending on the color and consistancy. He also stated that a temporal pterygium never occurs without a medial one and finally, he agreed with Richter in stating that a pterygium is always 1 preceeded by a pinguecula. Hubner, however, documented the fact that a pterygium could occur without originating from a pinguecula. This work was done in 1898.3 Merigot de Treigny and Coime reported in 1933 that pterygiums were most prevalent in countries with a hot, dry climate and one in which wind and dust are generally present~ - In 1936, Diponegoro and Mulock Houwer implicated infrared radiation as the causitive factor. 3 Beam and Dimitry suggested in 1945 that a choline deficiency was respon­ sible.-3 In 1954, hamel made a general statement that the pterygium was caused by chronic irritants which he did not specify. 3 I

clusion. 1 However, in 1967, Detels and Dhir did studies on sawmill em- ployees who worked indoors. They concluded that there was more than ul-

traviolet radiation alone that was responsible for the developement of

pterygiums.3

It can be seen from this brief history that the problem of the etiol-

ogy of the pterygium is a complex one. In order to simplify the compari-

son and evaluation of the theories, they will be grouped under five major

headings.

A. HEREDITX To substantiate any claim that heredity is a factor in the etiology

of pterygiums would be difficult since members of the same families us-

ually reside in the same environment. Control of the environment as a

variable would be essential in any study of heredity factors and this has

not yet been done. Studies on identical twins have been few and general-

ly inconclusive as well. 10 It has been reported that a baby born with a

pterygium had a paternal grandfather with a pinguecula. The attending

physicians ruled out an intrauterine infection as a possible cause, leav-

ing heredity as a possible factor instead. However, ophthalmologists

reviewing the case questioned if in fact it was actually a pterygium that was present. 15

Epidemiological data seems to indicate that heredity has very little,

if any, involvement in the etiology of pterygiums since family members

who move to an area of high incidence tend to develop them far more freq-

uently than those who remain behind. Page 10

B, PINGUECUU THEORY

. The theory that a pinguecula always preceeds a pterygium has been espoused by many persons.through the years. The most current proponents of this theory maintain that an irritant causes damage to the epithelial cells of the cornea and conjunctiva which subsequently die. The bare subepithelial cells then begin to proliferate and form a granulated tis- sue which grows above the level of the surrounding epithelial cells. This small elevation lies above the normal tear film layer and is thus subject to further drying, which can bring about further destruction and proliferation. The theory thus holds that the pterygium is always pre- ceeded by a pinguecula.9,11 In the following sections we will discuss the various explanations given as to what causes the pinguecula to form.

Other researchers have demonstrated that a pterygium can occur inde­ pendently of a pinguecula) and they also point out that the vast major- ity of pingueculas never develope into pterygiums. Few ~gue, however, that a pinguecula can preceed a pterygium.

C. CHRONIC IRRITATION

Chronic irritation, as a cause for pterygiums, may play a large or small part in many etiological theories. Irritants can be any material that can enter the eye in the fonn of particles. Dust appears to be the primary offender, especially when driven by strong winds.16 Sawdust has been implicated in a study of pterygiums among sawmill workers.3

Although solar radiation is also classified as an irritant, it will be discussed separately. Page 11

A hot, dry climate increases the effect of foreign particles in the eye by increasing the evaporation of tears. As ~~e rate of evaporation increases, the mucous membrane becomes directly exposed to the atmos- phere for a period of time during which dust gets onto the membrane and adheres. If this takes place over an extended period of time, hyperemia and cell death occur resulting in proliferation of the underlying tissue. 2 1 This process is thought to lead to the developement of a pterygium. • 3 This hypothesis has some epidemiological support in that pterygiums are most prevalent in hot, dry, dusty and windy areas. In the United States this would include the farm lands of the Midwest and the ranch areas of the Southwest. Ranchers and farmers who appear to have the greatest ex- posure to these irritants also are among the population of peoples with the highest incidence of pterygium developement.

It is thought by some that the reason temporal pterygiums are extremely rare is because the upper lid and offer much greater protection to the temporal conjunctiva than to the nasal conjunctiva.

Irritants, then, reach and irritate the temporal conjunctiva much less frequently and therefore cause fewer pterygiums. 8 ' 17

D. THE DRY EYE THEORY

The dry eye theory is closely related to the chronic irritation theory in that the dry eye allows irritants to act upon the conjunctiva in a way they normally would not be able to. However, a pterygium-like lesion has been seen in patients with superficial punctate drying alone.

This has been demonstrated by fitting a patient with a scleral contact . in which an air bubble rests in the same position on the conjunctiva. Page 12

Over a period of unspecified time the patient will develope a pterygium- . 18 lik~ lesion. A similar example is said to be seen in wearers of hard

contact lenses who develope 3-9 staining. This staining is said to be the ,, result of poor swiping of the area with tears due to the elevation,or a 19 20 d1srup. t e d bl"1n k mec h an1sm. . • The blink is either incomplete, of lower than normal frequency or a shpincter blink in which the facial muscles are

contracted to produce the blink. It is believed that in the case of the

sphincter blink, ~ll's phenomenon does not occur, leaving the cornea and 18 conjunctiva susceptible to damage through drying. The observation that

pterygiums do not occur in animals has been tied to the fact that animals

have no voluntary control over their blink rate mechanism as humans do.

Therefore, there is never a significant change in their blink rate and 18 thus a lac!< of dev.elopement of pterygiums.

In addition to a disrupted blink mechanism, other causes of a dry

eye might be due to a deficiency in any of the three tear layers, or an

altered corneal surface to which the rnucou s portion of the tear layer will 21 not adhere, A thorough discussion of the numerous conditions which

could cause a tear layer deficiency is beyond the scope of this paper.

However, suffice it to say that although two layers may be perfectly norm-

al and one layer is deficient, the entire tear layer is greatly reduced

in its fUnction of lubrication of the eye. It is also important to note

that an altered <;:orneal surface could be the result of a chronic irrita~

tion or trauma, Finally, continual exposure to a hot, dry wind can cause a , Page 13

Regardless of what may have caused the dry eye condition, most agree that once the eye is in this condition it allows irritants to have direct contact with the conjunctiva which eventually causes epithelial cell death and subepithelial proliferation. Therefore, this theory is equivalent to the chronic irritation theory and a dry eye in itself has not been shown to cause a pterygium. Goldvery, in 1976, claimed that there was no stat- istically significant correlation between the dry eye and pterygiums. 22

E. RADIATION

In the 1930's, infrared radiation was held by some to be a cause for pterygiums. Subsequently, however, it has been shown that the hotest geographical areas often have a lower incidence of pterygiums than cooler places9 and that heat alone has never been shown to produce specific bio- logical changes which are evident in pterygiums. 1

Ultraviolet radiation was first suggested to be a cause of pterygiums in 1933 but did not gain much popularity ~ntil the 1960's when Cameron wrote his book implicating ultraviolet light as the probable cause. The majority of theories today in some way contain ultraviolet light as a fac- tor. Cameron maintains that ultraviolet light penetrates the conjunctiva ar~ acts directly on the subconjunctival tissues, creating an inflammatory, fibroblastic response. The fibroblasts penetrate the space between Bow- man's Membrane and the epithelial basement membrane causing a fibrotic reaction and bringing about an ingrowth of connective tissue from the subconjunctiva. The subconjunctival tissue, which is already thickened because of the ultraviolet radiation, invades the cornea at the level of

Bowman's Layer. 1 Elliot, in 1966, implicated a photochemical reaction Page 14

wh~ch causes epithelial cell death as the initial step. When the epithe­ lial cells die, they leave the subepithelial cells exposed thus initiating proliferation. 9

Cameron bases his conclusion heavily on epidemiological evidence which shows a correlation between pterygiums and areas of high ultraviolet radiation and the fact that a study of spectacle wearers in a high inci­ dence area showed a markedly lower inciqence. 1 It should be remembered, however, that the areas of high ultraviolet radiation are often hot, windy and dry. The spectacle wearers, although not totally shielded from wind and dust, would be much more protected from them than the general popula- tion to which they were compared. Since the occupations of the spectacle wearers were not mentioned in the study, one may question if they were . carefully matched to those of the control group.

A study previously mentioned, by Detel and Dl~ir, in 1967, reported that indoor sawmill workers were developing pterygiums at a significantly greater rate than those not working at the mill. Data analysis also showed that the possibility of a person developing a pterygium incre~sed according to the rrumber of years they had worked in the mill_) This study would seem to nullify the theory that ultraviolet light alone is the cause of pterygiums since the workers had minimal exposure to that light due to working indoors. The possibility of limited exposure from working in a pond outside was not mentioned.

It is apparent that although several of the previously mentioned theories have some involvement in the etiology of pterygiums, no single theory is completely adequate in itself. Therefore, many additional Page 15 theories have been proposed which combine different portions of the above mentioned theories in an attempt to create a satisfactory completed theory.

This is exactly what the authors have done in developing an etiological theory. Essential to an etiological theory is the di'sruption of the subcon­ junctival tissue producing proliferation. This can be accomplished two ways. The first way is to be exposed to ultraviolet radiation. This pas­ ses through the epithelium and acts directly on subepithelial tissue pro­ ducing disruption and subsequent proliferation. Alternately, chronic ir­ ritation that is accompanied by, or ~uses production of, a dry eye in return causes epithelial cell death allowing irritants to act directly on subepithelial cells. This produces the same result as the ultraviolet radiation. It should also be noted that radiation and irritants can be working simultaneously to produce the changes. Therefore, if the expo­ sure is relatively mild or not continuous over an extended period of time, the final result may simply be a pinguecula. If, however, it is severe or the exposure is extended, a pinguecula may form and then pro­ ceed on to a pterygium or the proliferation may progress directly to the form of a pterygium,

As a result of the disruption of the subepithelial tissue, the epithelium becomes proliferative and begins to move towards the limbus.

The pterygium will become established at the limbus but will not in­ vade the cornea unless there is damage to the co~neal epithelium. The irritant that damages the corneal epithelium may vary. Dust, wind am Page 16 a dry eye seem to be the leading causes. As the corneal epithelium is damaged, invasion can occur since the prolifera t1 ve conjunctival epi th­ elium is reproducing at a faster rate that that of the corneal epithe­ lium. As the pterygium progresses, it begins to lose its nutritional support. At this time the corneal epithelium can reproduce equally as j fast, thus slowing and eventually stopping the invasion of the pterygium.

It can be seen then that a possibility of several factors can be at work in the developement of the pterygium. Ultraviolet light seems to be involved in the initial development in most cases, though not necessar­ ily so. Irritants play an important role, as does the dry eye. Admit­ tedly, this theory still leaves many questions unanswered. 11 Relatively mild" and "extended exposure" are terms indicating no precise inform.a.- . tion is available in these areas. The conclusion must be that although pterygiums have been described and studied for thousands of years, even with the most sophisticated instruments and methods available, a precise etiological theory has eluded us.

In order for optometrists to effectively use preventative treatment against pterygiums, it is necessary for them to apply the information just presented. We must know the many causative factors in order to pre­ scribe the most effective preventive measure or combination of measures.

The first of three factors we will be dealing with is the dry eye, a significant condition in the cause and developement o,:f pterygiums. A moist chamber, which is often accomplished with goggles, allows greatly increased fluid equilibrium to exist between the eye and its surroundings.

Therefore, the dry air often correlated with the occurence of pterygiums Page 17 is no longer a major influence in drying out the eye. Since a dry eye often develops over many years, a moist environment may not be sufficient in and of itself. Artificial tears as a wetting agent can be used alone or in conjunction with a moist chamber.

Irritants are the second factor we will consider. Once again, the same two means of prevention are used, as mentioned above, but this time with different functions in mind. Instead of being used to keep moisture in, the chamber is used to keep irritating particles out of the eye. The artificial tears perform the function of .flushing irritants out of the eye instead of wetting to prevent evaporation.

The third factor to be considered is ultraviolet radiation. Although we do not know the precise role ultraviolet light plays, it is certainly considered to be a contributor to the development of pterygiums. For this reason, precautions should be taken to protect the eyes from harm­ ful radiation. Under normal conditions, a regular spectacle prescription will provide adequate protection. If a person spends a great deal of time near water or snow, such as a fisherman would, extra precaution is recommended. Because the eyes receive multiple reflections as well as direct sunlight, specially tinted spectacles or goggles would give the necessary added protection.

Although prevention is the preferred choice of treating a patient, this is not always possible. In these cases, correct management of pterygiums needs to be considered.

There are two important questions that the optometrist must face in Page 18 the management of pterygiums. They are: 1) What is the criteria .for the referral of a pterygium for surgical treatment and 2) What type of surg­ ical treatment should be recommended{ These questions arise when opto­ metric treatment and management are unsuccessful or when the patient is

presented initially with an advanced pterygium.

The question of when shoul~ the optometrist refer the patient for

surgery is answered with an established three-point criteria.

A. When the pterygium extends one and one-half millimeters into the

cornea and is proliferative. Whether a pterygium is proliferative can be determined by the presence of edema in front of the head.

B.· Pterygiums which are stationary but are causing .

If not removed, this pterygium could shrink causing additional traction

on the cornea and produce even greater amounts of astigmatism. c. If the pterygium is over one and one-half millimeters and sta­

tionary, the patient may choose to have it removed for cosmetic reasons.2

Surgical removal has always been the initial choice of treat­ ment. Down through the centuries, a vast number of surgical techniques

and postoperative therapies have .been proposed and practised. In the ear­

ly 1800's, simple excision alone was practiced by Scarpa. Later, a flap

of neighboring conjunctival tissue was sewn over the bare area. 1 At the

turn of the century, McReynolds developed a technique in which the ptery­

gium was excised from the cornea and then directed downward by suturing

it to the inferior conjunctiva, A recurrence rate of 16% was reported at

that time1•6 Various types of grafts have been used to prevent recurrence. Page 19

The.se included skin grafts taken from under the upper arm23as well as . 24 mucous membrane grafts taken from the mouth. The purpose of the grafts was to provide a barrier against vascular regrowth. Finally, the bare technique has been used in which the subepithelial tissue is re- moved leaving the sclera exposed. This is most often used in conjunction with postoperative therapies.

Recurrence rates vary greatly from study to study but it has been estimated that surgery alone produces a recurrence rate of 20-60%. 25

Therefore, a number of postoperative therapies were developed in order to help prevent recurrence. Chemotherapy has been tried using the agent triethylene thiophosphoramide (thiotepa). The purpose of this drug is to inhibit rapidly proliferating cells. One study reported an 8~ recurrence rate and another 6%26 with little or no adverse effects. Others, however, reported scars and allergic reactions25 as well as the loss of lashes and lid pigmentation~ 4 Generally, this is not accepted as the method of choice, 8 Cautery27 •5and cryopexy (freezingfl have been used after surgery with some favorable results but others have argued that these methods will not stop the proliferation of some types of cells important in the recur­ rence of pterygiums. 2

Today most experts rely on beta-irradiation as the treatment of choice in most circumstances. ·There is a disagreement on two points, however.

This is in the area of how large of a dose of radiation should be given and how soon after the surgery should the treatment begin, The lens ab- sorbs approximately 15% of the radiation and a catarctogenic dosage is estimated to be when the lens absorbs 800 rads. This means a dosage of Page 20

5000 rads would be a boarderline cataractogenic dosage. However, cata- ractous changes have been observed in patients receiving as li ti;.le as 1400 29 rads, whil e others treat~ with 7000 rads showed no changes. Although 30 Hilgers suggests 5000 rads as the optimum dosage, most researchers sug- , 29,25 gest 3000 rads or less to be administered in two or three dosages~ 31 '32 ,33' . . while some use only 1000 rads or less, Studies us1ng radiahon doseages of 3000 rads or less rarely have patients with any de- . J4,30 velopement and report from a 3-0% recurrence rate.

General concensus among researchers has been that radiation therapy is most effective when it is begun immediately after surgery and no later . 35,25,29 . th 1 than 24 hours postoperatively. This l.S because e capi laries are thought to begin growing again within 24 hours and safe 9-osages of 29 radiation will not destroy already existing capillaries. However, in

1980, Cooper studied a sample of 272 pterygiums and reported that the recurrence rate among patients treated four days after surgery WdS less than half that among patients receiving their treatment before the third day pastoperatively. The authors propose that the delay in therapy al- lows surgical effects to heal, making the tissue more sensitive to the treatment. Another possibility is that the recurrence mechanism becomes 36 more sensitive to destruction by radiation after the fourth day.

Regardless of the doseage and treatment schedule employed in rad- iation therapy, the surgery of choice is the bare sclera technique. The entire pterygium must be removed as well as a one millimeter buffer zone beyond the head of the pterygium. This, of course, requires a keratectomy.

The base of the keratectomy must be smooth so that cells can slide over Page 21 it tn the process of regeneration. All conjunctival tissue is stripped away· as far back as the insertion of the medial rectus with a minimal width of two millimeters. This allows the corneal epithelium to regener­ ate and reach the limbus before the conjunctival epithelium, preventing 2 the conjunctival epithelium from invading the cornea. Radiation therapy is usually initiated within ·24 hours using Strontium 90. Treatment is given in two or three doses, one week apart. Also antibiotic steroid drops are used in conjunction with the radiation treatment. If recur- renee has not occured within five years, the patient is generally con- sidered to be cured .

Postsurgical optometric care consists of examining the patient per- iodically during the first year, twice during the second ye~r and yearl~ thereafter. The patient should be seen immediately if he notices any changes in the surgical area or reports irritation. Similar preventa- tive therapy should be administered in stopping recurrence as was ini- tially used to manage the pterygium. Special attention should be given to keeping potential irritants out of the eye and to keeping the eye moist.

Our function as optometrists and primary health care providers should be the overall management of the patient's eye care. The optomet- rist should decide when a patient should be referred for surgical eval- uation and which surgeon will provide the best care for each irrlividu- al patient. The optometrist also manages the patient postsurgically and provides long term follow-up. Therefore, as with cataract patients, it is essential that the optometrist knows which surgeons are best quali- fied and what type of surgery and treatment they prefer.~ Using this in- Page 22 formation, it is possible to establish a good working relationship in which the optometrist retains the patient for follow-up care.

Complications have been seen to occur with pterygiums although there is no prevalent or consistent pattern. One study found particular changes in . Specifically, an increase in with-the-rule astigma- tism was seen. In 46%, there was a change in astigmatism of more than

0.50 D and in 13% there was a change of 4.00 D or more!? Although the refraction changed, pterygiums were not seen to cause .

Also, the central corneal thickness was measured and found to be normal.3?

One case was cited in which bulbar ligneous conjunctivitis followed 38 the removal of a pterygium. It is not known how widespread or common this postoperative complication is.

Epithelial changes may be associated with the eccurrence of pterygi- urns. For example, epithelial proliferation has been seen, although squa­ 9 mous cell carcinoma is rare.J further changes also occur in the stroma which result in an epithelial inclusion cyst. The cyst has been found both superficially and deep, usually causing a bump or elevation. Fur- ther complications may occur as the cyst can become infected.

We have covered considerable information concerning pterygiums and their characteristics. We have also discussed the very important role the optometrist should have in dealing with pterygiums. It is necessary for optometrists to be aware .of this information in order to be able to use it in providing complete and proper care for their patients. FOarNOTES

1 Malcolm E. Cameron, Pterygium Throught the World (Springfield: . Thomas, 1965) 2 R. Elliot, "The Surgery of Pterygiums", Trans Oph thalmol · Soc NZ, 19 (1962) 27-34.

3c.o. Peckar, "The Aetiologh and Histo-pathogenesis of Pterygium. A Review of the Literature and a Hypothesis," Doc Ophthalmol, 31 (April 15,1972) 141-57. . 4 W. Kleis et al., "Thio-TEPA Therapy to Prevent Postoperative :ptery- gium Occurrence and Neovascularization," Am J Ophthalmol, 76 (September 1973) 371-3.

5G.L. Portney, ·~are Sclera, Scleral Cautery and Corticosteroid Therapy of Endemic Pterygium in the Navajo Indian," Amer J Ophthal, 67 c~~y 1969) 759-61. 6 R.M. Youngson, "Pterygium in Israel," Am J Qphthalmol, 74 (Novem- · ber 1972) 954-9.

7n. Sevel et al., "Pterygia and Carcinoma of the Conjunctiva," Trans Ophthal Soc UK, 88 (1969) 567-78. 8 V. Dolezalova, "Is the Occurrence of a Temporal Pterygium Really So Rare?," .Qphthalmologica, 174(2) (1977) 88-91.

9R. Elliott, "The Aetiology and Pathology of Pterygium," Trans Ophthal Soc Aust, 25 (1966) 71-4. 10 N.C. Faraldi et al., "Pt.erygium On Twins", Ophthalmologica,172(5) (1976) 361-6. 11 F. A. Hosni, "Pterygium in ·Q.a. tar," Ophthalmologica, 174 (2) ( 1977) 81-7.

1 ~rank W. Newell, Principles and Concepts, 4th ed. (St. Louis: Mosby, 1978) 226. 1 3w.w. Wong, "A Hypothesis on the Pathogenesis of Pterygiums," Ann Ophthalmol, 10(3) (~rch 1978 ) 303-8. . 14 . K. Olander et al., "Management of Pterygia: Should Thiotepa Be Used?," Ann Ophthalmol, 10(7) (July 1978) 853-62.

15virgil Schwartz, "Congenital Pterygium", JAMA,174 (1960) 2078-9. 16 John ~kReynolds, "The Nature and Treatment of Pterygia," JAMA, 39 (August 1902) 296-299.

17EJ Awan, "The Clinical Significance of a Single Unilateral Tempo­ ral Pterygium," Can J Ophthalmol, 10 (April 1975) 222-6. 18 I.A. Mackie, "Localized Corneal Drying in Association With Dellen, Pterygia and Related Lesions," Trans Ophthalmol Soc UK, 91 (1971) 129-45.

19D.R. Korb et al., Jour Amer Opt Assoc, 41, No 3, (1970) 7-10. 20 M.D. Sarver, Jour Amer Opt Assoc, 40, No 3, (1969) 310-313.

21c. Dohlman, "New Concepts in Ocular Xerosis," Trans Qphthalmol Soc UK, 91: 105-119. 22 H. Forsius et al., "Pterygium and its Relationship to Arcus Senilis, Pinguecula and Other Similar Conditions," Acta Ophthalmol, 40 (1962) 402- 410. 2 3w.w. Wong, "Behavior of Skin Grafts in Treatment of Recurrent Pterygium," Ann Ophthalmol, 9(3) (March 1977) 352-6. 24 1. }i. Trivedi et al., "Management of Pterygium and its Recurrence: by Grafting With Mucous Membrane From the Mouth," Amer J Ophthal, 68 (August 1969) 353-4. 2 5G. E. Rowen, "Ptertgium: Surgical ~xcision Followed by Beta Ir­ radiation," Rocky Mountain Med J, 65 (May 1968) 47-9. 26 J.M. Whaites, "The Prevention of Recurrent Pterygia," ~1ed J Aust, 1 (April 3, 1971) 739-40. 2 7M.E. Cameron, "Preventable Complications of Ptertgium Excision With Beta-Irradiation," Br J Ophthalmol,, 56 (January 1972) 52-6. 28 v.H. Monakhova, "Cryopexy in the Prevention of Pteryg ium Relapse," Survey Ophthol, 16 (1972) 388. . 29 . O.D. Pinkerton, "Surgical and Strontium Treatment of Fterygium: Recurrence and Lens Changes. Age Statistics," Ophthalmic Surg, 10(9) (September 1979) 45-7. .

JOJ.H. Hilgers, "Strontium 90 B-Irradiation, Cataractogenicity, and Fterygium Recurrence. Results of a Postirradiational Survey Five to Six Years After Treatment," Arch Ophthal, 76 (Chicago, September 1966) 329-JJ. 1 3 A.N. Talbot, "Complications of Beta Ray Treatment of Pterygia," Trans Ophthalmol: Soc NZ, 31 (1979) 62-J. 2 3 E.C. Tong et al., "Cellular Changes· in the Conjunctiva After Stron­ tium 90 Treatment for Pterygium," Amer J Roentgen, 106 (August 1969) 843-53.

33H.A. van den Brenk, "Results of Prophylactic Postoperative Irradi­ ation in 1,300 Cases of Fterygium," Amer J Roentgen, 103 (August 1968) 723-JJ.

J4 A. U. Herb stein et al., "Pterygium Removal. A Technique to Prevent Recurrence," Brit J Ophthal, 52 (February 1968) 162..;5.

35c. M. Haik, "The Management of Fterygia. A Third Report on a Com­ bined Surgical-Irradiation Technique," Amer J Ophthal, 61 (May 1966) 1128-34. 6 3 J. S. Cooper et al. , "Postoperative Irradiation of Pterygia: An Unexpected Effect of the Time/Dose Relationship," Radiology, 135(3) (June 1980) 743-5·

37A. Hansen et al. , "Astigmatism and Surface Phenomena in Pterygium," Acta Ophthalmol (Copenh), 58(2) (April 1980) 174-81. 8 3 s.M. Weinstock et al., ·~ulbar Ligneous Conjunctivitis After Ftery­ gium Removal in an Elderly Man," Am J Ophthalmol, 79(6) (June 1975) 913-5.

39M. Boniuk, "Pterygium With Epithelial Inclusion Cyst and Mycotic Infection," Survey Ophthal, 14 (May 1970) 457-60. BIBLICGRAPHY

Ansari, M.W. "Pseudoelastic Nature of Pterygium." Brit J Ophthal, 54:473- 476, July 1970.

Asregadoo, E.R. "Surgery, ThioOtepa, and Corticosteroid in the Treatment of Pteryium." Am J Ophthalmol, 74: 960-3, November 1972.

Awan, K.J. "The Clinical Significance of a Single Unilateral Temporal Pterygium." Can J Ophthalmol, 10(2): 222-6, April 1975.

Barraquer, J. Ophthalmologica, 150: 111-122, 1965.

Bernstein ~l. and S.M. Sunger. "Experiences With Surgery and Strontium-90 in the Treatment of Pterygium." AMS Ophthalmol, 49: 1024-1029, May 1960.

Boniuk, r1. "Fterygium With Epithelial Inclusion Cyst and Mycotic Infec­ tion." Survey Ophthal, 14: 457-60, May 1970.

Brenk, H.A. van den. "Results of Prophylactic Postoperative Irradiation in 1,300 Cases of Pterygium." Amer J Roentgen, 103: 723-33, August . 1968.

Cameron, Malcolm E. Pterygium Throughout the World. Springfield: Thomas, 1965.

"Beta-irradiation of Pterygia. Comparison of Different Areas Treated." Brit J Ophthal, 52: 562-3, July 1968.

------· "Preventable Complications of Pterygium Excision With Be­ ta-irradiation." Brit J Ophthal, 56: 52-6, January 1972.

Cilova-Atanasova, B. "On the Pathogenesis of Pterygium." Felia Med, (Plovdiv) 13: 67-74, 1971.

"Histological and Histochemical Changes of Epithelium, Basal Membrane and Bowman's Membrane in the Avascular Corneal Part of Pterygium." Folia Med (Plovdiv), 10: 23-6, 1968.

Cooper, J.S. "Postoperative Irradiation of Pterygia: An unexpected Effect of the Time/Dose Relationship." Radiology, 135(3): 743-5, June 1980. Dohlman, C. "New Concepts in Ocular Xerosis ... Trans Ophthalmol Soc UK, 91: 105-119.

Dolezalova, V. 11 Is the Occurrence of a Temporal Pterygium Really So Rare?" Ophthalmologica, 174(2): 81-7, 1977.

Elliott, R. "The Aetio1ogy and Pathology of Pterygium." Trans Ophthal Soc Aust, 25: 71-4, 1966.

---:-:-----:~~· "The Surgery of Pterygium." Trans Ophthalmol: Soc NZ, 14: 27-34, 1962.

Faraldi N.C. "Fterygium on Twins." Ophthalmologica 172(5): 361-6, 1976.

Forsius, H. "Fterygium and its Relationship to Arcus Senilis, Pingue- cula and Other Similar Consi tions." Acta Ophthalmol, 40: 402-410, 1962.

Goldberg, L. "Fterygium and its Relationship to the Dry Eye in the Bantu." Br J Qphthalmol, 60(10): 720-1, October 1976.

Haik, G.M. "The Management of Fterygia. A Third Report on a Combined Surgical-Irradiation Technique." Amer J Ophthal, 61: 1128-34, May 1966.

Hansen, A. "Astigmatism and Surface Fhenomena in Fterygium." Acta Ophth­ almol (Co penh), 58(2): 174-81, April 1980.

Herbstein, A. U. "Pterygium Removal. A Technique ot Prevent Recurrence." Brit J Ophthal, 52: 162-5, February 1968.

Hilgers, J.H. "Strontium 90 B-irradiation, Cataractogenicity, and Ptery­ gium Recurrence. Results of a Postirradiational Survey Five to Six Years After Treatment." Arch Ophthal (Chicago), 76: 329-33, September 1966.

Hosni, F.A. "Pterygium in Qatar." Ophthalmologica, 174(2): 81-7, 1977.

Kleis, W. 11Thio-tepa Therapy to Prevent Postoperative Pterygium Occur­ rence and Neovascularization." Am J Qphthalmol, 76: 371-3, September 1973.

Kerb, D.R. Jour Amer Opt Assoc, 41, No, 3r 7-10, 1970.

levy, W. J. "Fterygium Tissue Culture Histoimmunological Study. " Arch Ophthal (Chicago), 83: 402-5, April 1970.

}'Jackie, I. A. "Localized Corneal Drying in Association With Dellen, Ptery­ gia and Related Lesions." Trans Ophthalmol Soc UK, 91 : 129-4 5, 1971.

}1cReynolds, John. "The Nature and Treatment of Pterygia." JMA, 39: 296- 299, August 1902. Monakhova, V, H. "Cryopexy in t.J,e Prevention of Pterygium Relapse." Sur­ vey Ophthal, 16: 388, 1972.

Newell, Frank W. Ophthalmology Principles and Concepts. 4th ed., St Lou­ is: Mosby, 1978.

Olander, K. "~1anagement of Pterygia: Should Thiotepa be Used?" Ann Ophth­ almol, 10(7); 853-62, ·July 1978.

Peckar, C.O. "The Aetiology and Histo-pathogenesis of Pterygium. A Re- view of the Literature and a Hypothesis." Doc Ophthalmol, 31: 141-57, April 15, 1972.

Pinkerton, O.D. "Surgical and Strontium Treatment of Pterygium: Recur­ rence and Lens Changes. Age Sta tis tics, " Oph thalrni c Surg, 10 ( 9) : 4 5- 47, September 1979.

Poirier, R.H. "lamellar Keratoplasty for' Recurrent Pterygium." Ophthal­ mic Surg, 7(4): )8-41, Winter 1976.

Portney, G, L. "Bare Sclera, Scleral Cautery and Corticosteroid Therapy of Endemic Pterygium in the Navajo Indian." Arner J Ophthal, 67: 759- 761, May 1969.

Raizada, I.N. "Histopathology of Pterygium." Eye Ear Nose Throat Monthly, 47: )40-3, July 1968.

Reeh, M.J. "Corneoscleral lamellar Transplant for Recurrent Pterygium." Arch Ophthalrnol, 86: 296-7, September 1971.

Rich, A.M. "A Simplified Way to Remove Pterygia." Ann Ophthalrnol, 6: 739-42, July 1974.

Rowen, G. E. "Pterygium: Surgical Excision Followed by Beta-irradiation." Rocky Mountain Med J, 65: 47-9, May 1968.

Sarver, M.D. Jour Am Opt Assoc, 40: No 3: · 310-313, 1969.

Schwartz, Virgil. "Congenital Pterygium. " JAMA, 174: 2078-2079, 1960.

Sen, D. K. "Surgery of Pterygium, Modified McGavic' s Technique." Brit J Ophthal, 54: 606-8, September 1970.

Sevel, D. "Pterygia and Carcinoma of the Conjunctiva." Trans Ophthal Soc . UK, 88: 567-78, 1969.

Small, .R.G. "A Technique for Removal of Pterygium." Ann Ophthalrnol, 9(3): 349-50, March 1977.

Talbot, A. N. "Complications of Beta Ray Treatment of Pterygia." Trans Ophthalrnol: Soc NZ, 31: 62-3, 1979. Ta ylor, H.R. "Studies on the Tear Film in Climatic Droplet l\eratopathy and Pterygium," Arch Ophthalmol, 98(1): 86-8, January 1980.

Tong, E. C. "Cellular Changes in the Conjunctiva After Strontium 90 Treat­ ment for Pterygium." Amer J Roentgen, 106: 848-53, August 1969.

Tranos, L. "Cutting Forceps: For Pterygium and Symblepharon." Amer J Ophthal, 68: 356, August 1969.

Trivedi, L. K. "Management of Pterygium and its Recurrence: By Grafting With Mucous Membrane from the Mouth." Amer J Ophthal, 68: 353-4, Aug- ust 1969.

Weinstock, S.M. ·~ulbar Ligneous Conjunctivitis After Pteryg ium Removal in an Elder],y Man." Am J Ophthalmol, 79(6): 913-5, June 1975.

Whaites, J.M. "The Prevention of Recurrent Pterygia." Med J Aust, 1: 739-40, April 3, 1971.

Wong, W.W. "A Hypothesis on the Pathogenesis of Pterygiums." Ann Ophthal­ mol, 10(3): 303-8, March 1978.

• ·~ehavior of Skin Grafts in Treatment of Recurrent Ptery­ --g....,.i_u_m-. ,':7",-:A-nn Ophthalmol, 9(3): 352-6, March 1977,

Youngson, R.M. "Pterygium in Israel." Am J Ophthalmol, 74: 9.54-9, Nov­ ember 1972.

"Recurrence of Pterygium After Excision." Br J Ophthalmol, 56: 120-5, February 1972.'