Diabetic Retinopathy

High blood sugar levels caused by diabetes can damage blood vessels in the retina, the nerve layer at the back of the eye that senses light and helps to send images to the brain.

Types
There are two types of diabetic retinopathy: nonproliferative (NPDR) and proliferative (PDR).

Nonproliferative, or background retinopathy, is an early-stage version in which tiny blood vessels within the retina leak blood or fluid. The leak causes the retina to swell or form deposits called exudates. Many people with diabetes have mild NPDR, which usually doesn't affect their vision. When vision is affected, it is the result of macular edema and/or macular ischemia.

Causes
Macular edema is swelling or thickening of the macula, a small area in the center of the retina which allows us to see fine details clearly. The swelling is caused by fluid leakage. It is the most common cause of visual loss in diabetes. While vision loss may be mild or severe, peripheral vision continues to function.

Macular ishemia occurs when small blood vessels close. Vision blurs because the macula no longer receives sufficient blood supply to work properly.

PDR occurs when abnormal new vessels begin to grow on the surface of the retinal blood vessels, due to widespread closer of retinal vessels which prevents adequate blood flow.

The new blood vessels do not resupply the retina with normal blood flow and can produce scar tissue that may cause wrinkling or detachment of the retina.

PDR may cause more severe vision loss than NPDR because it can affect both central and peripheral vision.

Diagnosis
If you have diabetes, it is important to know that today only a small percentage of people with retinopathy have serious vision problems. Early detection is the best protection against vision loss. A medical eye examination by an opthalmologist can often diagnose and treat serious retinopathy before any vision problem is even apparent. People with diabetes should schedule examinations at least once a year. Pregnant women with diabetes should schedule an appointment in the first trimester because retinopathy can progress quickly during pregnancy.

Last Updated: December 03, 2007