Diabetic retinopathy: a leading cause of new blindness.

Some of the basic underlying processes in the development of diabetic retinopathy include changes in the walls of retinal vessels, with occlusion and leakage. These result in edema, hemorrhage, hard exudates, plaques, and ischemia, leading to neovascularization. When proliferative retinopathy supervenes, it may result in complete blindness. Internists and family practice physicians should be alert for early signs of diabetic retinopathy. Ideally, diabetic patients should have their eyes examined yearly by an ophthalmologist. A fundus examination without dilation and usually without acuity testing rarely detects proliferative or early background retinopathy. Multicenter studies have shown that photocoagulation of new vessels with the argon laser may significantly reduce the incidence of severe visual loss. This treatment method has the potential of reducing the incidence of diabetic blindness by 60% to 80%. Photocoagulation is not a "cure" for diabetic macular edema; when used judiciously, however, it can sometimes further reduce visual loss caused by this common disease. The course of diabetic retinopathy in individual cases is unpredictable. After photocoagulation, some patients cannot see as well as before, though in others the progress of the disease is arrested. There is a conservative concern about a procedure that destroys retinal tissue in the hope of limiting the progression of the disorder. Yet photocoagulation appears to be the only alternative until a better treatment is developed through basic research.