Diabetic retinopathy: current concepts of evaluation and treatment

Diabetic retinopathy is a common, and potentially blinding or visually disabling complication of diabetes. Nearly all diabetic subjects will have some degree of retinopathy after 20 years of diabetes, and 50% of those with insulin dependent diabetes will have proliferative retinopathy after 15 years. Macular oedema frequently produces central vision loss and legal blindness, most commonly in non-insulin dependent diabetics. In recent years, several therapeutic modalities have been demonstrated to be effective on the basis of large-scale randomized, controlled clinical trials. These include panretinal photocoagulation (PRP), using the argon laser or xenon arc, for proliferative retinopathy, and focal photocoagulation for macular oedema. Vitrectomy surgery is effective for diabetic vitreous haemorrhage and traction retinal detachment, producing improved vision in most patients, but only a relatively small percentage of patients so treated recover good visual acuity (greater than or equal to 6/12). Other therapeutic modalities, such as hypophysectomy for severe retinopathy, remain controversial, while still others, such as rigorous blood glucose control and aldose reductase inhibitors, are currently under investigation. The primary care physician who deals with diabetic patients should be familiar with the lesions of diabetic retinopathy and with current therapeutic modalities. He should perform an examination of the posterior retina with the direct ophthalmoscope on each diabetic patient at each visit, and should institute prompt referral to an ophthalmologist at the first sign of change. Periodic examination of all diabetic patients by an ophthalmologist should be conducted at the intervals recommended in the previous section. Definitive evaluation and treatment of diabetic retinopathy should be carried out by the ophthalmologist.