Page 81 - NAME OF CONDITION: REFRACTIVE ERRORS

the Wisconsin ARMD grading system. The stages as defined by the Wisconsin group

are:
Category 1: No AMD
No or a few small drusen(<63 microns in diameter)
Category 2: Early AMD
Many small drusen or a few intermediate sized drusen(63-124 microns in diameter)
or macular pigmentary changes
Category 3: Intermediate AMD
Extensive intermediate drusen or at least one large drusen(≥125 microns), or
geographic atrophy not involving the foveal center.
Category 4: Advanced AMD

Geographic atrophy involving the foveal center (atrophic or dry AMD)
Choroidal neovascularisation (wet AMD) or evidence for neovascular maculopathy
(Sub retinal haemorrhage, serous retinal or RPE detachments, lipid exudates or
fibrovascular scar).

II. INCIDENCE OF THE CONDITION IN OUR COUNTRY:
Several incidence and prevalence studies have been undertaken in various parts of

India. These studies show an overall prevalence of AMD in India for early AMD is
similar to that seen in western countries. However, the incidence of late AMD is
found to be comparatively less. The prevalences of early and late age-related
macular degeneration were 2.7% (95% CI, 2.2%-3.2%) and 0.6% (95% CI, 0.4%-0.8%),
respectively (ACES 2004). Another study found the overall prevalence of AMD in
south India to be 1.87% (APEDS 2005). Most recent data show a prevalence of
blindness in late AMD of 1.8% (INDEYE study).This data indicates that the condition is
rapidly increasing or is being increasingly recognized and is a significant health

hazard and cause for blindness in our country.
III. DIFFERENTIAL DIAGNOSIS

The widely variable clinical presentation and sometimes unpredictable natural
history are important confounding features in the correct diagnosis of AMD. Variable
degenerative and dystrophic diseases of the retina and RPE, in which pigmentary

mobilization or lipofuscin accumulation are major findings, share fundamental
clinical features with the dry form of the disease.
The common differential diagnoses for dry AMD are
 Bests disease
 Pattern dystrophies of RPE
 Cuticular drusen, pseudo vitelliform detachment
 Stargardts disease.

 Central serous retinopathy.
 Chloroquine toxicity
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