Retinopathy screening in individuals with type 2 diabetes: who, how, how often, and at what cost--an epidemiologic review.

Despite treatment regimens, which can reduce blindness, diabetic retinopathy remains the leading cause of irreversible blindness for persons less than 75 years. Screening for diabetic retinopathy in type 1 diabetes mellitus has proven to be both efficacious and cost effective. Although treatment has been shown to be equally efficacious for type 2 diabetes, the effectiveness and cost benefit of screening are less clear.A systematic review of the recent literature on the epidemiology of retinopathy in type 2 diabetics was carried out. Specific issues related to the changing epidemiology of diabetes and diabetic retinopathy, as well as the effectiveness, and cost benefit of screening were evaluated.Diabetic retinopathy is at the convergence of several epidemiologic trends. Although the prevalence of diabetic retinopathy within the population of diagnosed diabetics may be decreasing because of aggressive risk factor reduction, any gains achieved are likely to be negated by the large increase in the prevalence of type 2 diabetes in the population owing to obesity. The epidemiology findings suggest that certain persons with well-controlled type 2 diabetes may not warrant yearly examination for diabetic retinopathy; however, given the low percentage of diabetics who are currently screened for retinopathy, it would seem unwise to recommend changes in the timing of examination. Evidence appears to suggest that photoscreening is a viable alternative to a screening examination.