Diabetic macular edema and argon laser photocoagulation: a prospective randomized study.

Loss of vision from diabetic retinopathy can result from complications of neovascular proliferation, or frequently, from macular edema secondary to background diabetic retinopathy. Although the benefits of photocoagulation for proliferative diabetic retinopathy have been clarified by the National Eye Institute's collaborative diabetic retinopathy study, those for background diabetic retinopathy with macular edema remain unclear. Several articles have described the visual benefits and reduction of edema following photocoagulation of eyes with background diabetic retinopathy and macular edema, but only Patz's study was prospectively designed utilizing a random assignment of laser treatment for one eye with the other eye remaining untreated. This article reports the two-year results of a similar prospective study in which one eye in each of 39 patients with symmetrical macular edema secondary to background diabetic retinopathy was randomly selected to receive argon laser photocoagulation, while the fellow eye remained untreated.