assessment & management of patients with cataract

Assessment & management Assessment & management of patients with cataractof patients with cataract

Prevalence & morphologyPrevalence & morphology Cataract with VA < 6/9: 5% in 55-64 age group,

40% in 75+ age group.

Three major types:

cortical (~60%)

nuclear (~40%)

PSC (~20%)

• Some have mixed cataract. Early nuclear changes

tend to be called normal age changes rather than

cataract.

Cortical

most prevalent accounts for 63% of cases

wedge shaped opacities found in anterior and/or cortical posterior lens cortex

opacification due to light scatter

found in the infero-nasal portion of lens

Nuclear

accounts for 41% of cases

homogenous in light scatter in the lens nucleus

can be associated with lens yellowing

Posterior Sub-Capsular (PSC)

accounts for 24% of cases

occur at back of lens in front of the posterior capsule

localised in refractive index and accompanying vacuole formation

centrally positioned

Vision loss in cataractVision loss in cataract

Could be caused by:

increasing myopia and astigmatism, monocular diplopia,

reduced light transmission

changes in colour perception

Mainly due to increased light scatter, and changes in pupil size.

Case HistoryCase History Guidelines have suggested the following indications

for cataract surgery:

Visual acuity (VA) is 6/15 or worse and is solely due to cataract.

The patient decides that the expected improvement in function outweighs the potential risk, cost and inconvenience of surgery after being given appropriate information

The patient's ability to function in their desired lifestyle is reduced due to poor vision.

Binocular visionBinocular vision Be wary of monocular diplopia, caused by

acute refractive index changes.

Can decrease or increase with progression.

? block second image with black strip.

Make sure not due to uncorrected astigmatism, likely in cortical cataract.

Objective refractionObjective refraction Difficult due to reduction in light returning.

ARs tend not to be able to provide a result.

Use radical retinoscopy (move closer, careful with distance as inc. risk of error, no difference to error in astigmatism).

Use as few lenses as possible (each one loses you 8% of light via reflections).

Subjective refractionSubjective refraction..

JND is larger, therefore use ±0.50D or more.

JCC should be ±0.50, ±0.75 or ±1.00 DC.

Look for increased minus with nuclear cataract.

Look for increased/ changes in astigmatism with cortical cataract.

Clinical vision testsClinical vision tests

Although referral is based on case history and Px’s symptoms, it should be justified by reduced vision on one or more clinical tests.

i.e. the surgery should be able to return vision on these tests to normal values. This will hopefully resolve the Px’s symptoms.

Visual acuity (VA)Visual acuity (VA)

Distance VA is the traditional clinical test.

Provides a reasonable assessment of vision in the real world in many cases (but not all).

Best measured with a logMAR chart.

Near VA can provide useful information, especially with PSC cataracts.

logMAR chart

contrast sensitivity at low to intermediate frequencies is in cataract Pxs

surgery can return these values to age-matched normal values

the best available test for use is the Pelli-Robson chart

Pxs with contrast sensitivity 1.35 are likely to complain of poor vision

Contrast sensitivity (CS)Contrast sensitivity (CS)

Pelli-Robson CS chart

Contrast sensitivity (CS)Contrast sensitivity (CS)

See Clinical Optometry II notes.

Mrs. D.H.: Homemaker, age 68 years, with extensive cortical cataract R & L and Sxs of great difficulty recognising friends, reading and knitting, with much worse vision in bright sunlight.

VAs: R: 6/6, L: 6/7.5. Reduced Pelli-Robson CS (1.05 and 1.35 log) provided justification for surgery. The right cataract was extracted (the eye with the better VA but the worst CS) and this provided significant improvement in visual ability.

Disability Glare & Colour Disability Glare & Colour VisionVision

See Clinical Optometry II notes.

NB for glare: case record of Rubin (1972).

NB for colour: Monet.

Note that Ishihara only assesses Red-green problems.

Note that diabetics as well as getting colour problems due to retinal changes, also get cataract earlier.

Brightness Acuity Tester

Stereopsis and Visual fieldsStereopsis and Visual fields

Poor stereopsis can be useful when referring 2nd eye cataract patients.

Cataract causes problems of interpretation of fields in glaucoma and may be removed to aid treatment in diabetics.

Localised opacities tend not to cause localised fields, but can alter mean sensitivity and the pattern (CPSD).

Slit-lamp biomicroscopySlit-lamp biomicroscopy

Assesses backscatter.

Nuclear - optic section.

Cortical and PSC - retro-illumination (direct ophthalmoscope is good).

Draw PSC and cortical. Can get classification systems to accurately grade.

Check corneal endothelium.

Fundus examinationFundus examination Co-morbid disease is the biggest cause of

“unsuccessful” surgery.

Use Volk: Far, far better view through cataract than direct (dilated or not).

Also get 3-D view and better FOV.

May need to dilate.

Refer Pxs with ARMD etc. if have moderate/ dense cataract.

Potential Vision TestsPotential Vision Tests

Simple indicators: age, diabetes, hypertension, macular disease in other eye.

Swinging flashlight test.

? PAM, ? Retinometer.

Best future test? The Bradford Reading speed test!

Management of patients with Management of patients with cataractcataract

Referral: see previous guidelines.

Latham & Misson study (1997):

Optometrists: 6/18;

Ophthalmologists: 6/9

but Optometrists refer too early (??!!).

Referral letters: indicate the patient’s problems (basis for referral) and then clinical test results (justification).

Counselling Counselling

“Have I got cataract?”

Use clinical definition. Always then describe cataract (not “skin over eyes”) and explain how good modern surgery is.

If lens opacity is not affecting vision, you could say they have an age change in the lens that could turn into a cataract later.

Inform Px if they have a PSC.

CounsellingCounselling

“Can I drive?”

Cataract Pxs may have 6/9+ VA in your exam room, but see little when night driving or driving on a sunny day (use glare test).

Document advice and perhaps inform GP.

Pxs may consider this advice when deciding whether to be referred for surgery.

Prognosis and follow-upPrognosis and follow-up

Cortical and nuclear tend to be slowly progessive: 5-10 years after first noted.

Lens opacity: 2 year follow-up.

Cataract: 1 year follow-up

Cataract-induced myopia or astigmatism that is quickly progressing, some patients with PSC or other rapidly progressing cataract: 3 or 6 months.

Removal of risk factorsRemoval of risk factors

Stop / reduce cigarette smoking.

Use UV blockers.

Use anti-oxidant vitamins (C,E, beta-carotene).

CounsellingCounselling

“Use up my eyes”: advise Pxs that longevity of sight cannot be ensured by small daily use of the eyes (like withdrawals from a bank).

Typoscopes: great for improving reading in cataract.