Diabetic Retinopathy

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What are the stages of diabetic retinopathy?

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 retina's tiny blood vessels. There are no symptoms at this stage of the disease.
    
2. Moderate Nonproliferative Retinopathy. As the disease progresses, more microaneurysms form, some blood vessels that nourish the retina are blocked and begin to leak blood and serum. Typically there are no symptoms at this stage of the disease.
    
3. Severe Nonproliferative Retinopathy. Many more blood vessels are blocked, depriving several areas of the retina with 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 damaged retina for nourishment trigger the growth of new blood vessels. This condition is called proliferative retinopathy because these new vessels proliferate (grow) across the inner surface of the retina and along the surface of the clear, vitreous gel that fills the inside of the eye. These new vessels are abnormally fragile and are prone to bleeding profusely, causing vitreous hemorrhage that can severely reduce vision. Though vitreous hemorrhage may clears over time, it is accompanied by the development of fibrovascular scar tissue that may contract, pulling the retina off the back wall of the eye and resulting in permanent vision loss or blindness (traction retinal detavchment). About 30,000 cases of new proliferative diabetic retinopathy develop in the US each year.

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 result.

Who is at risk for diabetic retinopathy?

All people with diabetes—both type 1 and type 2—are at risk. That's why everyone with diabetes should get a comprehensive dilated eye exam at least once a year. Between 40 to 45% of Americans diagnosed with diabetes have some stage of diabetic retinopathy and up to 25% of newly diagnosed type 2 patients will already have retinopathy at diagnosis. If you have diabetic retinopathy, your doctor can recommend treatment to help prevent its progression.

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

How does diabetic retinopathy cause vision loss?

Vitreous hemorrhage and traction retinal detachment caused by proliferative retinopathy can both cause vision loss. Blood vessels damaged from diabetic retinopathy can cause vision loss in two ways:

1. Fragile, abnormal blood vessels can develop and leak blood into the center of the eye, blurring vision. This is proliferative retinopathy and is the fourth and most advanced stage of the disease.
    
2. Fluid can leak into the center of the macula, the part of the eye where sharp, straight-ahead vision occurs. The fluid makes the macula swell, blurring vision. This condition is called macular edema. It can occur at any stage of diabetic retinopathy, although it is more likely to occur as the disease progresses. About half of the people with proliferative retinopathy also have macular edema. About 100,000 new cases of diabetic macular edema occur each year in the US.

Does diabetic retinopathy have any symptoms?

Diabetic retinopathy often has no early warning signs. Don't wait for symptoms. Be sure to have a comprehensive dilated eye exam at least once a year.

What are the symptoms of proliferative retinopathy if bleeding occurs?

Patients often see a few specks of blood, red smudges or spots obscuring or "floating" in their vision. If this occurs, see your eye care professional as soon as possible. You may need treatment before more serious bleeding occurs. Hemorrhages tend to happen more than once, often during sleep.

Sometimes, without treatment, the spots clear, and you will see better. However, bleeding can reoccur and cause severely blurred vision. You need to be examined by your eye care professional at the first sign of blurred vision, before more bleeding occurs.

If left untreated, proliferative retinopathy can cause severe vision loss and even blindness. Also, the earlier you receive treatment, the more likely treatment will be effective.

Reviewed by Dr. A. Paul Chous, MA OD, FAAO. 4/12

Excerpted from the National Eye Institute, NIH Publication No.03-2171