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retina

A disease of the small blood vessels of the eye. Diabetic retinopathy is a sight-threatening condition that affects 80% of people who have had diabetes for 15 years. In most cases, however, blindness can be prevented.

High blood glucose levels and other blood chemistry changes resulting from diabetes cause damage to the tiny blood vessels of the eye. This damage reduces the supply of oxygen to the retina, the

light-sensitive tissue at the back of the eye that transmits visual images to the brain. To correct this decrease in oxygen supply, the retina grows new blood vessels, but they are weak and prone to leaking blood and fluid.

Diabetic retinopathy has three stages. Many people with diabetes develop background retinopathy, in which the blood vessels in the retina leak fluid (called hemorrhaging). This fluid may accumulate in the central part of the retina (the macula), causing it to swell (a condition called macular edema) and resulting in blurred vision. Background retinopathy can advance to preproliferative retinopathy, in which more hemorrhaging occurs.

The third stage is called proliferative retinopathy. In this stage, abnormal new blood vessels grow over the surface of the retina. These fragile new blood vessels tend to hemorrhage into the vitreous humor, the clear gel that fills the eye cavity, causing vision loss. Another danger at this stage is that scar tissue can pull on the retina and cause detachment.

Diabetic retinopathy can now be treated, even in its early stages, by laser photocoagulation, which is done in the ophthalmologist’s office on an outpatient basis. The treatment uses a narrow laser beam to pinpoint tiny areas of the retina, where it closes off the new, abnormal blood vessels and prevents them from growing.

Occasionally, even after laser treatment, there is bleeding in the eye severe enough to cloud vision. If this happens, vitrectomy can be performed. In this procedure, blood is drawn out of the vitreous humor. At the same time, the new, leaking blood vessels can be coagulated using a tiny laser called an endophotocoagulator.

Research shows that controlling your blood sugar levels can reduce your risk of developing diabetic retinopathy. In the landmark Diabetes Control and Complications Trial (DCCT), the results of which were published in 1993, people with Type 1 diabetes who used intensive insulin therapy (rather than standard insulin therapy) lowered their chances of developing diabetic retinopathy by 76%.