Diabetic retinopathy is a potentially blinding complication of diabetes that damages the eye's retina. It affects half of all Americans diagnosed with diabetes.

At first, you may notice no changes in your vision. But don't let diabetic retinopathy fool you. It could get worse over the years and threaten your good vision. With timely treatment, 90 percent of those with advanced diabetic retinopathy can be saved from going blind.

The National Eye Institute (NEI) is the Federal government's lead agency for vision research. The NEI urges all people with diabetes to have an eye examination through dilated pupils at least once a year.

What is the retina?
The retina is a light-sensitive tissue at the back of the eye. When light enters the eye, the retina changes the light into nerve signals. The retina then sends these signals along the optic nerve to the brain. Without a retina, the eye cannot communicate with the brain, making vision impossible.

How does diabetic retinopathy damage the retina?
Diabetic retinopathy occurs when diabetes damages the tiny blood vessels in the retina. At this point, most people do not notice any changes in their vision.

Some people develop a condition called macular edema. It occurs when the damages blood vessels leak fluid and lipids onto the macula, the part of the retina that lets us see detail. The fluid makes the macula swell, blurring vision.

As the disease progresses, it enters its advanced, or proliferative, stage. Fragile, new blood vessels grow along the retina and in the clear, gel-like vitreous that fills the inside of the eye. Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina.