Diabetic Retinopathy

Diabetic eye disease is the number one cause of blindness in working-age Americans. In the early stages, diabetic eye disease has no obvious symptoms. If you have diabetes mellitus, high blood-sugar levels can damage blood vessels in the retina, the layer of light sensitive cells at the back of the eye. The damage to retinal vessels is called diabetic retinopathy.

Types of Diabetic Retinopathy

There are two types of diabetic retinopathy: Non-Proliferative Diabetic Retinopathy (NPDR) and Proliferative Diabetic Retinopathy (PDR).

Non-Proliferative Diabetic Retinopathy (NPDR)

In this stage, vision may initially be unaffected. Later, tiny blood vessels within the retina can begin to leak blood or fluid. The leaking fluid causes the retina to swell (macular edema) or to form deposits called exudates. If this occurs in the center of the retina, it will blur your vision. When vision is affected it is usually the result of macular edema. Other times it can be due to the closing off of the blood vessels in the retina (macular ischemia). Vision blurs because the macula no longer receives sufficient blood supply to work properly.

Proliferative Diabetic Retinopathy (PDR)

PDR is present when abnormal new vessels begin growing on the surface of the retina, the optic nerve or the iris. The main cause of PDR is widespread closure of retinal blood vessels, preventing adequate blood flow. The eye responds by growing new blood vessels. Unfortunately, the new, abnormal blood vessels are not functional. The new vessels can bleed and are often accompanied by scar tissue that may cause wrinkling or detachment of the retina. PDR may cause severe vision loss in the following ways:

Vitreous Hemorrhage
The fragile new vessels may bleed into the vitreous, a clear, jelly-like substance that fills the center of the eye. If the vitreous hemorrhage is small, a person might see only a few new dark floaters. A very large hemorrhage might block out all vision. It may take days, months or even years to resorb the blood, depending on the amount of blood present. If the eye does not clear the vitreous blood adequately within a reasonable time, vitrectomy surgery may be recommended. Vitreous hemorrhage alone does not cause permanent vision loss. When the blood clears, visual acuity may return to its former level as long as other structures in the eye are stable.

Traction Retinal Detachment
When PDR is present, scar tissue associated with neovascularization can shrink, wrinkle and pull the retina from its normal position. Macular wrinkling can cause visual distortion. More severe vision loss can occur if the macula or large areas of the retina are detached.

Neovascular Glaucoma
Occasionally, extensive retinal vessel closures will cause new, abnormal blood vessels to grow on the iris (colored part of the eye) and block the normal flow of fluid out of the eye. Pressure in the eye builds up, resulting in neovascular glaucoma, a severe eye disease that causes damage to the optic nerve and severe vision loss and pain.

How is diabetic retinopathy diagnosed?

A medical eye examination can find changes inside your eye. An eye care specialist can often diagnose and treat serious retinopathy before you are aware of any vision problems. Your doctor dilates your pupil and looks at the inside of your eye.

If your eye doctor finds diabetic retinopathy, he or she may order color photographs of the retina and a special test called fluorescein angiography to find out if you need treatment. In this test, fluorescent dye is injected into a vein in your arm and your eye is photographed as the dye passes through the blood vessels in the back of the eye.

Diabetic Retinopathy Treatment

The best treatment for diabetic retinopathy is to prevent it’s development. Strict control of your blood sugar will significantly reduce the long-term risk of vision loss from diabetic retinopathy. If high blood pressure and kidney problems are present, they need to be treated.

Laser surgery is often recommended for people with macular edema, PDR and neovascular glaucoma. For macular edema, the laser is focused on the macula to decrease the fluid leakage. The main goal of treatment is to prevent further loss of vision. It is uncommon for people who have blurred vision from macular edema to recover normal vision, although some may experience partial improvement.

For PDR, the laser is focused on all parts of the retina except the macula. This panretinal photocoagulation treatment causes abnormal new vessels to shrink and often prevents them from growing in the future. It also decreases the chance that vitreous bleeding or retinal distortion will occur. Recently, eye injections have become a useful tool in the management of diabetic retinopathy.

Multiple eye injections or laser treatments over time are sometimes necessary. These procedures do not cure diabetic retinopathy and does not always prevent further loss of vision. Sometimes, in severe cases, a patient may need to see a retina specialist to discuss more involved surgery.

Vision loss to diabetic retinopathy is largely preventable.

If you have diabetes, it is important to know that today, with improved methods of diagnosis and treatment, only a small percentage of people who develop retinopathy have serious vision problems. Early detection of diabetic retinopathy is the best protection against loss of vision. You can significantly lower your risk of vision loss by maintaining strict control of your blood sugar and visiting your eye care specialist regularly.

When to schedule an examination.

People with diabetes should schedule examinations at least once a year. More frequent medical eye examinations may be necessary after the diagnosis of diabetic retinopathy. Pregnant women with diabetes should schedule an appointment in the first trimester because retinopathy can progress quickly during pregnancy.

If you need to be examined for glasses, it is important that your blood sugar be in consistent control for several days when you see your doctor. Glasses that work well when the blood sugar is out of control will not work well when blood sugar is stable. Rapid changes in blood sugar can cause fluctuating vision in both eyes, even if retinopathy is not present. You should have your eyes checked promptly if you have visual changes that:

• Affect only one eye.
• Last more than a few days.
• Are not associated with a change in blood sugar.

Get EyeSmart

Visit the American Academy of Opthalmology’s webpage on Diabetic Retinopathy.