National Eye Institute

Diabetic retinopathy is a complication of diabetes and a leading cause of blindness. It occurs when diabetes damages the tiny blood vessels inside the retina, the light-sensitive tissue at the back of the eye. A healthy retina is necessary for good vision.

If you have diabetic retinopathy, at first you may notice no changes to your vision. But over time, diabetic retinopathy can get worse and cause vision loss. Diabetic retinopathy usually affects both eyes.

Diabetic retinopathy has four stages:

1. Mild nonproliferative retinopathy: At this earliest stage, microaneurysms occur. They are small areas of balloon-like swelling in the tiny blood vessels of the retina.
2. Moderate nonproliferative retinopathy: As the disease progresses, some blood vessels that nourish the retina are blocked.
3. Severe nonproliferative retinopathy: Many more blood vessels are blocked, depriving several areas of the retina of their blood supply. These areas of the retina send signals to the body to grow new blood vessels for nourishment.
4. Proliferative retinopathy: At this advanced stage, the signals sent by the retina for nourishment trigger the growth of new blood vessels. This condition is called proliferative retinopathy. These new blood vessels are abnormal and fragile. They grow along the retina and along the surface of the clear, vitreous gel that fills the inside of the eye. (See diagram above.)

By themselves, these blood vessels do not cause symptoms or vision loss. However, they have thin, fragile walls. If they leak blood, severe vision loss and even blindness can occur.

All people with diabetes, both type 1 and type 2, are at risk, which is why everyone with diabetes should get a comprehensive dilated eye exam at least once a year. Between 40 to 45 percent of Americans diagnosed with diabetes have some stage of diabetic retinopathy. If you have diabetic retinopathy, your eye care professional can recommend treatment to help prevent its progression.

During pregnancy, diabetic retinopathy may be a problem for women with diabetes. To protect vision, every pregnant woman with diabetes should have a comprehensive dilated eye exam as soon as possible. Your eye care professional may recommend additional exams during your pregnancy.

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