The treatment of diabetic retinopathy: a view for the internist.

Purpose: To review the status of surgical and medical therapy for diabetic retinopathy from the perspective of the non-ophthalmologist.

Data Sources: Relevant English-language articles published from January 1981 to July 1991 were identified through MEDLINE. Other relevant articles were obtained from the authors' personal database.

Study Selection: For the review of surgical treatment, large randomized, controlled trials were selected. For the review of medical treatment, randomized studies comparing intensive insulin treatment with conventional insulin therapy were selected, as were double-blind, randomized, controlled trials of aldose-reductase inhibitor therapy and antiplatelet therapy in patients with diabetic retinopathy.

Data Extraction: Emphasis is on findings from large, multicenter, randomized, controlled studies.

Data Synthesis: Surgery is effective in three clinical situations: Panretinal (scatter) photocoagulation is effective treatment for proliferative retinopathy that is likely to progress to severe visual loss, with such therapy resulting in a 50% to 60% decrease in the main outcome (visual acuity of 5/200 or less; focal photocoagulation decreases the incidence of deterioration of visual acuity by 60% in patients with clinically significant macular edema, but no benefit of photocoagulation has been shown in patients with mild-to-moderate background diabetic retinopathy; and vitrectomy is effective in improving visual acuity only in patients with severe, complicated proliferative retinopathy. Intensive insulin therapy has not been consistently effective in short-term studies with small numbers of subjects. Results of the Diabetes Control and Complications Trial should show whether intensive insulin therapy affects the course of diabetic complications. Aldose-reductase inhibitors have not shown efficacy in changing the course of diabetic retinopathy. Results of trials using antiplatelet agents are controversial.

Conclusions: Current therapy of diabetic retinopathy is based on detection and surgical treatment of advanced lesions. Medical interventions that effectively halt the progression or prevent the development of diabetic retinopathy are needed.