Aims: To determine which screening and monitoring tests for diabetic retinopathy are most effective and under what circumstances.
Methods: A systematic review of the English language literature, published from 1983 to April 1999.
Results: Available studies are generally limited in their ability to answer the important questions on the effectiveness of tests for early detection of diabetic retinopathy. No randomized controlled trials were identified although primary studies exist for two screening tests: ophthalmoscopy, either direct or indirect, and retinal photography, using either mydriasis or non-mydriasis. Retinal photography under mydriasis appears to be the most effective test, with the majority reporting levels of sensitivity in excess of 80%. However effectiveness is compromised when photographs are ungradable. Ophthalmoscopy can also reach acceptable standards of sensitivity and specificity.
Conclusion: Based on an assessment of available cohort studies, the most effective strategy for testing is the use of mydriatic retinal photography with the additional use of ophthalmoscopy for cases where photographs are ungradable. This does not exclude the use of ophthalmoscopy alone for opportunistic case finding but there is evidence of considerable variation in effectiveness of this test.