Screening for diabetic retinopathy in South Africa with 60 degrees retinal colour photography

Abstract

Objectives: Comparison of 60 degrees mydriatic retinal photography, in screening for diabetic retinopathy, with diabetes clinic doctors, formal ophthalmological assessment, and with one or two 45 degrees fields.

Design: Consecutive subjects screened by clinicians and photography, and selected eyes evaluated by an ophthalmologist. Randomized photographs assessed through one or two 45 degrees fields (by masking the slides), and at 60 degrees.

Setting: The first 663 patients attending for routine clinic visits and screened for retinopathy.

Main outcome measures: The relative diagnostic sensitivity of screening methods, the utility of screening one eye only, and the costs of photographic screening.

Results: Compared to an ophthalmologist's assessment, retinal photography had a sensitivity of 93% and a specificity of 89% for any retinopathy, and 100 and 75%, respectively, for severe retinopathy. Photography detected 28% more retinopathy (16% severe) than the clinicians. Compared to a 60 degrees field, one 45 degrees field missed 31%, and 2 x 45 degrees fields 11% of retinopathy. Of 57 patients with retinopathy meeting referral criteria, 31 pairs of eyes had substantially discordant scores. The cost of diagnosis in a patient requiring referral to ophthalmologist was about US $37.00.

Conclusions: 60 degrees retinal photography compares well with an ophthalmologists screening, and is better than clinical and one to two 45 degrees field assessments. Both retinae should be screened. This method is cost-effective in our hands.