Purpose:
To assess the feasibility of using a modified Rapid Assessment of Avoidable Blindness framework to estimate diabetic retinopathy (DR) prevalence, and its contribution to visual impairment in three low and middle income countries.
Methods:
Clusters of 50 (40 in South Africa) people aged 50 years or older were selected by probability proportionate to size sampling. Households within clusters were selected through compact segment sampling. Participants underwent visual acuity (VA) screening and diagnosis of cause of visual impairment by an ophthalmologist. Participants were classed as ‘Diabetic’ if they had a previous diagnosis of diabetes, were receiving treatment for blood glucose control or had a random blood glucose level >200mg/dl. Diabetic participants were assessed for DR using: dilated clinical examination (direct and indirect ophthalmoscope) and one dilated digital fundus photograph per eye (graded by a retinal specialist - "reference standard") following the Scottish DR grading protocol. The main outcome measures were: prevalence of blindness (VA<20/400 in the best eye with available correction) and prevalence of DR.
Results:
DR prevalence is shown in the table. The prevalence of blindness was 2.3%(1.7-2.9) in Chiapas, 1.4%(0.9-1.8) in Cape Town, and 2.6%(2.0-3.2) in Taif. Cataract caused 63% of blindness in Chiapas 41% in Taif and 27% in Cape Town. Posterior segment diseases were responsible for 24% of blindness in Chiapas, 44% in Taif and 65% in Cape Town. DR caused 8% of blindness in Chiapas, 8% in Cape Town, and 10% in Taif.
Conclusions:
The prevalence of diabetes and DR was high in all three centers. The surveys show that there is an unmet need for both laser treatment and for programs to detect and treat DR. It was feasible to include assessment of DR within the survey and the results will assist program planning. Including the DR component added to the cost and complexity of the survey, and so would only be warranted if a high prevalence of diabetes is expected, and if resources and time permit.
Keywords: diabetic retinopathy • clinical (human) or epidemiologic studies: prevalence/incidence