Aspirin in diabetic retinopathy. A systematic review

Diabetes mellitus is a risk factor for eye disease that can lead to blindness. There have been both concerns that aspirin use might worsen diabetic retinopathy, as well as hopes that aspirin might be beneficial in treating it. We investigated whether there are beneficial effects of aspirin alone and in combination with other antiplatelet agents in the treatment of diabetic retinopathy, and the relative hazards for the development of high-risk proliferative retinopathy following aspirin treatment. We conducted a sensitive search for randomized controlled trials combined with index terms for identifying studies on aspirin treatment in diabetic retinopathy in the Cochrane Library (issue 4, 2001) and Medline (1966 to October, 2001). We examined randomized controlled clinical trials in diabetic patients with (non) proliferative diabetic retinopathy and aspirin treatment alone or in combination with dipyramidole versus placebo administration. Two independent reviewers judged trial eligibility, collected details of study population, interventions, and outcomes using a standard data extraction form. One reviewer assessed the quality of trial reporting. We identified six publications pertinent to our objective. Aspirin dosages ranged from 650 mg to 990 mg daily, the dose of dipyridamole, used in only one trial, was 225 mg per day. Studies lasted 8 weeks to 5 years. All trials showed that aspirin alone or in combination with dipyridamole neither lowered nor increased the risk of the development of diabetic retinopathy. The results suggest that there are no ocular contraindications to taking aspirin if required as part of a treatment for cardiovascular diseases or other medical indications.