Continuing education CET Assessment of the patient with cataract In the second of our four-part series, Kenneth Fong and Raman Malhotra describe the best procedures for assessment of a patient with cataract with a view to referral and surgery (C6014, two standard CET points)

anagement of the patient fore also be encountered during cataract with cataracts is a multi- surgery due to zonular dialysis. disciplinary team affair in ● Vitreous opacification which optometrists play ● Diabetic retinopathy a key role. Optometrists Cataract surgery in diabetic patients has M must take a good patient history to deter- been associated with a higher incidence mine if cataracts are actually affecting of post-operative complications, includ- the patient’s quality of life, and whether ing fibrinous uveitis, posterior capsule treatment would be beneficial. They opacification, anterior segment neovas- must explain what cataracts are and cularisation, accelerated progression how they are managed, without causing of diabetic retinopathy, and macular undue alarm to the patient. The primary Figure1 Pseudoexfoliation (PXF). The same eye under greater oedema. Post-operative visual acuity purpose in managing a patient with magnification showing PXF deposits on the anterior lens may therefore be poor. A number of cataract is to improve functional vision capsule issues relating to cataract surgery in and quality of life. inquiry should be made into the patient’s diabetes remain incompletely resolved, daily, occupational, leisure, and social including appropriate timing of surgery, When should a patient be activities and document any cataract- determinants of visual outcome, impact referred for cataract surgery? related impairment. If the patient holds of surgery on retinopathy, and optimal Cataracts are often discovered during a driving licence, then the legal visual management of postoperative macular routine optometric examination and requirements for, and symptoms affect- edema. patients are usually asymptomatic. It is ing driving should be determined. Patients with diabetic retinopathy imperative to discuss with the patient The optometrist must also identify must be carefully examined prior to whether they actually want cataract co-existing ocular conditions as predic- cataract surgery. The key question is surgery before referring them to an tors of poor visual outcome following whether the patient has proliferative ophthalmologist. Cataract surgery surgery. These include: diabetic retinopathy (PDR) or macular guidelines by the Royal College of ● Corneal pathology oedema. If either or both cases are Ophthalmologists (www.rcophth. This includes corneal opacities, degener- present, it is essential to counsel the ac.uk/about/publications/) suggest that ative disorders, hereditary conditions (in patient about the guarded prognosis to patients should be referred for surgery particular, Fuch’s endothelial dystrophy their vision after cataract surgery. if there is sufficient cataract to account and corneal oedema) and ectasia. If the patient has PDR, this needs to for their visual symptoms and that these ● Glaucoma be treated as much as possible with pan- limit their quality of life and ability to Uncontrolled intraocular pressure (IOP) retinal laser photocoagulation (PRP) work or drive, irrespective of Snellen or visual field loss. prior to cataract surgery. If the cataract visual acuity. Cataract surgery may be ● Uveitis is severe enough to preclude a good view appropriate for a patient who has good ● Pseudoexfoliation of the retina for adequate PRP, then Snellen visual acuity, but complains of Most commonly found in the urgent cataract surgery is warranted. It glare or problems with night driving. Scandinavian or northern European may be then possible to perform PRP Conversely, surgery may be inappro- population, pseudoexfoliation is charac- with an indirect viewing system at the priate for a non-driver with adequate terised by a deposition of a white time of surgery after the cataract has been reading vision but poor distance acuity, fluffy material (similar to amyloid) removed, or if this is not possible, PRP if they are happy with their current level on the anterior lens capsule, with a should be arranged within one week of vision. Simply put, the risks of cataract relatively clear zone corresponding to of surgery. If PDR is present, cataract surgery should be outweighed by the the movement of the iris (Figure 1). In surgery will accelerate its progression anticipated benefits. addition, this material is deposited on the and the visual results can be poor if the Once a cataract is diagnosed, the zonules, iris pigment epithelium, ciliary PDR is not treated aggressively. optometrist should first determine epithelium, trabecular meshwork and Macular oedema may be difficult to the overall effect of cataract on visual cornea. The pupil often fails to dilate detect clinically if a cataract is present. If function and the well-being of the fully, potentially making cataract surgery macular oedema is seen prior to cataract patient. These assessments will serve more challenging. This condition may surgery, this should be treated with a as the basis for a decision whether to lead to glaucoma, as well as weakness focal or grid laser. A pre-operative fundus recommend cataract surgery. A careful of the zonules. Complications may there- fluorescein angiogram (FFA) is helpful

24 | Optician | 16.02.07 opticianonline.net CET Continuing education

in identifying areas of macular oedema optic nerve function. Most importantly, Group 1 drivers (car and other and leakage from active new vessels. If retinal detachment or intraocular tumour light vehicles) macular oedema is present at the time must be excluded and may require the All drivers are required by law to read of cataract surgery, it will most likely use of a B-scan ultrasound. a standard-sized number plate in good worsen with time if left untreated. Where a significant opacity precludes light at 20.5m. In September 2001, the All patients who have diabetic retin- retinal visualisation, optic nerve and new-format number plate was intro- opathy who have had cataract surgery retinal function may be clinically duced on all new and replacement need to be seen within one week after assessed by way of confrontational visual plates. The characters are narrower than their operation for a dilated retinal field testing and the ability to detect light the current number plate and this new examination. Any evidence of PDR or in all four quadrants of the uni-ocular format plate should be read at 20 metres. macula oedema should be treated as soon visual field. The number plate test is absolute in law as possible to prevent progression of the Furthermore, the response of the pupil and not open to interpretation. A driver disease. Cataract surgery appears to cause to light and the presence of a relative who is unable to satisfy this requirement progression of diabetic retinopathy but afferent pupillary defect (RAPD) should is guilty of an offence under Section not diabetic maculopathy. be determined. Cataract, even if mature, 96 of the Road Traffic Act 1988. The ● Age-related macular should not cause an RAPD. number plate test corresponds to a binoc- degeneration (AMD) ● Amblyopia ular visual acuity of approximately 6/10 Patients with AMD may suffer further ● Optic nerve or neurological Snellen acuity. However, it is important deterioration of their visual acuity due disease to stress that visual acuity measurements to cataract and the majority would in a consulting room may not correspond experience significant improvements in The ‘only eye’ patient to the ability to read the standard number quality of life as well as visual function Patients who only have good vision in plate at the roadside. following cataract surgery. This is partic- one eye will naturally be more concerned ularly the case with increasing severity about the prospect of surgery. Modern Group 2 drivers (large goods/ of cataract, irrespective of the degree cataract surgery carries much lower risk passenger carrying vehicles) of AMD. Cataracts are known to cause than before and, in general, the thresh- All new Group 2 applicants since January reduced distance and near visual acuity, old for intervention should not be set at a 1, 1997 must by law have: as well as contrast sensitivity, by reduc- higher level for such patients. Increased ● A visual acuity of at least 6/9 in the ing the quality and physical contrast in sensitivity in counselling is also required. better eye, and the retinal image. The reduced contrast ● A visual acuity of at least 6/12 in the sensitivity is a consequence of forward Urgent cataract surgery worse eye, and scatter of light from the lens produc- There are unusual circumstances ● If these are achieved by correction, ing the effect of veiling glare, which in which cataract surgery should be the uncorrected visual acuity in each eye obviously improves when cataracts are expedited. When a cataract is mature, must be no less than 3/60. removed. an inflammatory reaction may occur Despite the presence of AMD, daily with acutely raised intraocular pressure. Pre-operative hospital living activities involving the detection Cataract surgery is also expedited in assessment of objects at low physical contrasts are narrow-angle glaucoma, particularly if The minimum ocular examination therefore likely to benefit from cataract a significant phacomorphic component should include testing for a relative affer- surgery. Furthermore, peripheral retinal- exists. Such patients should be referred ent pupillary defect, confrontational function, particularly that for lower urgently to an ophthalmologist for visual field examination, assessment of spatial frequencies may improve. surgery. the ocular surface to exclude blepharitis, Of concern is the finding by some Recent research has also revealed that conjunctivitis, dry eyes or obvious nasol- studies that suggest that eyes with AMD in older patients, cataracts may play an acrimal blockage. During the slit-lamp that undergo routine cataract surgery important role in the causation of car examination, special attention should be are at a slightly greater risk of progres- accidents, falls causing fractures, and paid to the corneal endothelium and the sion to wet AMD in comparison to the functional decline. Hence, earlier visual status of support for the lens. Pre-exist- fellow eye. This implies that cataract rehabilitation through modern cataract ing corneal endothelial pathology (for surgery may be an important possible surgery with intraocular lens implanta- example, Fuch’s dystrophy) or zonular risk factor in progression of macular tion is becoming not only an option but weakness (such as pseudoexfoliation) degeneration. the norm. should be highlighted in the referral, as Patients with AMD must decide both would increase the risk of complica- whether to proceed with cataract surgery Visual standards for driving tions from cataract surgery. Intraocular in the face of uncertain information The following are the minimum visual pressure should be measured prior to about the ultimate result. acuity standards required for driving, pupillary dilatation. During dilated ● Retinal vascular disorders as applied by the Driving and Vehicle fundus examination, one should look out Signs of previous branch or central Licensing Authority. There is also a visual for diabetic retinopathy, AMD and optic retinal vein, or arterial occlusion may be field standard which is not statutory. The neuropathy, in particular, glaucoma. subtle but should be suspected, partic- visual field standard for ordinary driving ularly if the loss of visual function is is currently defined as ‘a field of at least Pre-operative medical not commensurate with the degree of 120° on the horizontal, measured using investigations cataract. the Goldmann III4e setting or the equiv- Based on the Royal College of ● No view of fundus alent. In addition, there should be no Ophthalmologists’ guidelines for local Lack of a clear retinal view may be due significant defect in the binocular field anaesthesia for intraocular surgery, a to significant corneal opacity, dense or which encroaches within 20° of fixation patient due to undergo cataract surgery mature cataract or a vitreous opacity. This either above or below the horizontal with no history of significant systemic influences the ability to assess retinal and meridian.’ disease and no abnormal findings on opticianonline.net 16.02.07 | Optician | 25 Continuing education CET

Figure 2 Preoperative photograph during phacoemulsification cataract surgery using iris hooks for retraction and also, Trypan blue (and ‘vision blue’) to stain the anterior capsule to allow capsulorhexis to be easily performed in the absence of a red reflex during surgery Figure 3 Visual acuity chart based on logMAR scale examination at a nurse-led assessment Table 1 intraocular lens implant is chosen during does not require special investigations. Preoperative tests required prior to cataract cataract surgery. For example, if the Any patient requiring special tests may surgery patient is highly myopic in both eyes need a medical opinion. Key points to and only has a cataract in one, careful consider are: ● Refraction discussion with the patient is needed in ● Systemic hypertension should be ● Near and distance visual acuity selecting the intraocular lens power for controlled well before the patient is ● Biometry the affected eye. If the operated eye is left scheduled for surgery and not lowered ● B-scan ultrasonography if no fundus view emmetropic after surgery – as is normally immediately prior to surgery obtainable done in most cases – there is a high risk of ● Angina should be controlled by a ● Other optional tests – Corneal topography, post-operative anisometropia. As such, patient’s usual angina medication which specular microscopy aim for post-operative low myopia in the should be available in theatre. Every operated eye. If the myopic patient has effort should be made to make the experi- Flomax and intra-operative floppy cataract in both eyes, then emmetropia ence as stress-free as possible. Generally, iris syndrome is a possible option, provided that the patients should not have surgery within A significant proportion of men aged second eye is operated on soon after the three months of a myocardial infarct 60 and older with cataracts also have first eye. Myopic patients often dislike ● Diabetic patients should have their benign prostatic hypertrophy (BPH). being left even slightly hypermetropic blood sugar controlled. If surgery is The BPH drug Flomax (tamsulosin after cataract surgery. As such, practition- planned under local anaesthesia, diabetic hydrochloride) causes iris complications ers usually aim for their post-operative patients should have their usual medica- during phacoemulsification, known refraction to be slightly myopic. tion and oral intake as intraoperative floppy iris syndrome ● Patients with chronic obstructive (IFIS). IFIS describes a floppy iris that Near and distance visual acuity pulmonary disease may benefit from billows in response to normal intraocu- The best corrected visual acuity for an open draping system or high flow lar fluid currents, a strong propensity near and distance should be obtained. oxygen-enriched air system below the to iris prolapse and progressive miosis Although Snellen measurements are drapes intra-operatively. Complications more commonly used for distance ● There is no need for antibiotic prophy- related to IFIS may be reduced (see acuity, logMAR visual acuity (Figure laxis for intraocular surgery in patients below). It should be noted that Flomax 3) measurements provide a better and with valvular heart disease is prescribed for some women with more accurate means of comparing ● Those on warfarin should have an INR urinary retention. pre- and post-operative visual acuity. It check (international normalised ratio ● Ask patients before cataract surgery is important to realise that visual acuity describes the results of a blood clotting if they’re taking Flomax. Discontinuing measurements are only one test for visual test) prior to surgery (see below). the drug for two weeks before surgery performance. It does not always relate to may lessen the iris’s floppiness, though vision in environments of variable light- Medication not eliminate it. Any prior history of ing conditions, in which glare and pupil Warfarin and cataract surgery Flomax use is important because IFIS constriction may reduce the effective The RCO’s guidelines for cataract cases can still occur in those who discon- visual acuity. surgery state that to stop warfarin risks tinued the drug, even one to two years stroke and death. The INR should be earlier Biometry checked to ensure that a patient is within ● Common techniques such as mechani- Biometry measurements of both eyes are their desired therapeutic range set by cal pupil stretching or partial thickness essential prior to cataract surgery. This is the treating physician, and if needle sphincterotomies do not appear to work normally performed in the hospital by local anaesthesia is performed, the risk for IFIS trained nurses, orthoptists or optome- of orbital haemorrhage is increased by ● Disposable iris retractors (Figure 2) or trists. Determination of the lens implant 0.2-1.0 per cent. Either sub-Tenon’s or pupil expansion rings are the best way power to give any desired postoperative topical anaesthesia is recommended for to maintain a larger pupil. refraction requires measurement of two these patients. key variables at a minimum; the anterior Aspirin Refraction corneal curvature in two orthogonal Aspirin is generally not discontinued An accurate pre-operative subjective meridians and the axial length of the eye. prior to cataract surgery. refraction is vital to ensure the correct These measurements are then entered

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technique. The normal axial length of B-scan ultrasonography the eye is between 22.0-24.5mm. B-scan ultrasonography is useful in The A-mode transducer is commonly eyes with dense cataracts that preclude 5mm in diameter and emits short a visual assessment of the posterior pulses of weakly focused ultrasound segment. This is to exclude coincidental at a frequency of 10MHz. In the inter- pathology (for example, retinal detach- vals between these emissions, echoes ment and choroidal tumour) that may are received by the same transducer, be present and which may impact on the converted to electric signals, and plotted post-operative result of cataract surgery. as spikes on a display. The accuracy of measurements from a skilled operator Other optional tests — corneal in a regularly shaped eye is generally topography, specular microscopy within 0.1mm. Corneal topography can be a useful An optical interferometer specifi- investigation to show the true shape cally designed for lens implant power of the cornea prior to cataract surgery. calculation is commercially available This can help the surgeon plan the sites – IOL Master; Carl Zeiss – (Figure 4). of the incisions in cases of high corneal into an appropriate formula. Figure 4 This system is widely used in most astigmatism by either operating on the Keratometers measure anterior IOL Master ophthalmic units and can measure the steep corneal meridian or combining corneal curvature over a small annular (Zeiss) used axial length, keratometry and anterior the procedure with corneal relaxing zone (usually between 2-4mm in diame- in biometry chamber depth of the eye. It uses a low incisions at the site of the steep meridian. ter) and assume this is spherical. Contact measure- coherence Doppler interferometer to This will allow a better post-operative lenses should be removed at least 48 ments prior measure axial length. In-built formu- refractive result to occur. hours prior to keratometry, because their to cataract lae allow calculation of lens implant As the corneal endothelium is vulner- long-term use can induce a reversible surgery power. Dense cataracts, corneal or vitre- able to damage during cataract surgery, corneal flattening. There are a variety ous opacities may preclude measure- it is sometimes useful to document the of manual, automated and hand-held ment with this system. The system is a status of the endothelium with specu- keratometers available. non-contact one and is ideal in terms of lar microscopy. This assessment has a The axial length of the eye is measured patient comfort and compliance. This prognostic value for corneal survival from the corneal vertex to the fovea and system has proved to be highly accurate after cataract surgery. can be measured using either A-mode and simple to use in a variety of difficult In the event that the cornea has a ultrasound or an optical interferometric measurement situations. reduced endothelial cell count prior to

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opticianonline.net 16.02.07 | Optician | 27 Continuing education CET

surgery, the surgeon can counsel the patient appropriately regarding the Multiple-choice questions increased risk of corneal decompensa- tion from cataract surgery. Which of the following would least merit C Measurements should be by a Goldmann IIIe 1cataract surgery? setting or equivalent Issues to consider for A Driver with good high contrast acuity but D There should be no significant binocular field presbyopic cataract patients complaining of glare defect within the central 20 degree field With the increasing improvements in B Diabetic whose fundus view is obscured by cataract surgery techniques and technol- cataract Which of the following is true regarding ogies, the demand for a better post-opera- C Housebound patient with significantly 7Flomax? tive result is increasing (for example, reduced acuity but able to carry out all visual A It is primarily used by women spectacle independence after surgery). tasks to their satisfaction B Patients using Flomax are never able to have As many of our patients attending for D Driver unable to read the new number plate cataract surgery cataract surgery are already in the presby- format at 20m C It leads to intraoperative floppy iris syndrome obic age group, presbyobic lens exchange D Mechanical pupil stretching is unlikely to help or ‘Prelex’ has become a possibility. Which of the following corneal changes treat IFIS This allows the patient to be free of 2is unlikely to lead to poor post-cataract optical correction aids, like spectacles, surgery visual outcome? Which of the following postoperative for near or distance work after cataract A Fuch’s endothelial dystrophy 8refractive states is preferred by most surgery. B Corneal ectasia practitioners? Prelex is now possible due to a combi- C Corneal opacification A Slight myopia nation of factors: D Corneal astigmatism B Emmetropia ● Accurate biometry C Slight hyperopia ● Precise and complication-free modern Which of the following statements is NOT D A monovision state cataract surgery 3true about pseudoexfoliation? ● Reduction of pre-existing astigmatism A It presents with white deposition on the Which of the following is NOT true at the time of cataract surgery anterior lens capsule 9regarding the IOL Master instrument? ● The availability of multifocal and B It may cause a secondary open-angle A It is an ultrasound interferometer accommodative intraocular lenses glaucoma B It might not be useful in cases of dense (IOL). C It may lead to zonular dialysis cataract The ideal patient for Prelex is a hyper- D It is most prevalent among Afro-Caribbeans C It uses low coherence Doppler interferometry opic presbyope who dislikes wearing D It automatically calculates lens implant power glasses and has clinically significant lens Which of the following is true concerning changes. 4diabetes and cataract? Why might a B-scan ultrasound scan The patient must also be able to accept A Patients with diabetic retinopathy should be 10be useful prior to cataract surgery? the possible need for glasses even after assessed within 3 months of cataract surgery A It predicts axial length accurately uneventful cataract surgery. B Cataract surgery appears to cause a B It allows calculation of IOL power They must also be aware of the need progression of diabetic retinopathy C It may detect significant retinal disease to adjust to a new visual system and C Macular oedema is best treated post-cataract behind an optically dense cataract to accept that the ability to have good extraction D The technique is no longer used in relation to unaided near vision may take a period D Cataract extraction causes progression of cataract surgery of time to develop. maculopathy Which of the following patients is Summary Which of the following is true concerning 11ideal for Prelex? Cataract is the leading cause of age- 5AMD and cataract? A Young myope with traumatic cataract related visual loss and will become more A Cataract extraction increases the risk of wet B Hypermetropic presbyope who does not want common with society’s increasing life AMD compared with the fellow eye spectacles expectancy. B Cataract extraction will not enhance the C Patient with established maculopathy prior to Given the magnitude of the associated vision of a patient with established AMD cataract extraction healthcare burden, an expanded role for C Cataract extraction will increase glare in an D Myopic presbyope the optometrist in patient assessment, AMD patient preparation and aftercare for cataract D Cataract extraction will improve peripheral Why might topography be useful surgery is inevitable. As such, it is essen- vision in AMD, particularly higher spatial 12prior to cataract surgery? tial for optometrists to have good knowl- frequencies A It helps predict the IOL power edge of the condition and surgery as B It allows correct ordering of any contact lens integration between ophthalmic health- Which of the following is NOT true that may be needed post-surgery care professionals continues. ● 6regarding the visual field standard for C It will screen for any pre-surgical corneal driving? opacities ● Kenneth Fong is a specalist registrar in A There must be at least 120 degrees of D It allows the surgeon the possibility of ophthalmology based in London. Raman horizontal field correcting corneal cylinder as part of the Malhotra is a consultant ophthalmic and B It is a statutory requirement extraction procedure oculoplastic surgeon at The Queen Victoria Hospital, East Grinstead, West Sussex To take part in this module go to opticianonline.net and click on the Continuing Education section. Successful participation in each module of this series counts as two credits towards This article is based on a chapter in Cataract the GOC CET scheme administered by Vantage and one towards the Association of by Raman Malhotra, a forthcoming book in Optometrists Ireland’s scheme. The deadline for responses is March 15 the Elsevier Science Eye Essentials series

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