Diabetic Eye Disease
Approximately 16 million Americans have diabetes. And half are at risk for vision loss because they don't know they have the disease.

Diabetic eye disease, a group of eye problems that affect those with diabetes, includes diabetic retinopathy, cataracts and glaucoma. The most common of these is diabetic retinopathy.

Diabetic retinopathy is a potentially vision threatening condition in which the blood vessels inside the retina become damaged from the high blood sugar levels associated with diabetes.

Because there are often no symptoms in the early stages of diabetic retinopathy, your vision may not be affected until the disease becomes severe. You should see your ophthalmologist promptly if you experience visual changes that:

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

Diabetes can also affect your vision by causing cataracts and glaucoma. If you have diabetes, you are likely to get cataracts at a younger age and your chances of developing glaucoma are doubled.

More than one third of those diagnosed with diabetes don't get recommended vision care and may be at risk for blindness. Once diagnosed with diabetes, you should have your eyes examined at least once every two years.

Early diagnosis of diabetes and the effective control of blood sugar levels, Hemoglobin A1C and hypertension through diet and exercise can help control eye diseases associated with diabetes.

What are the symptoms of diabetic retinopathy?
Because there are often no symptoms in the early stages of diabetic retinopathy, your vision may not be affected until the disease becomes severe. You should see your ophthalmologist promptly if you experience visual changes that:

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

You should have a dilated eye exam or retinal photographs at least once every two years.

What causes diabetic retinopathy?

If you have diabetes mellitus, your body does not use and store sugar properly. Over time, 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. The damage to retinal vessels is referred to as diabetic retinopathy. The center of the retina is referred to as the macula or fovea

What are the types of diabetic retinopathy?

Diabetic retinopathy is classified into two types: nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). NPDR is generally considered the milder form, although both forms can cause significant vision loss.

Nonproliferative diabetic retinopathy (NPDR)

Nonproliferative diabetic retinopathy (NPDR), commonly known as background retinopathy, is an early stage of diabetic retinopathy. In this stage, tiny blood vessels within the retina leak blood or fluid. The leaking fluid causes the retina to swell or to form deposits called exudates.

Many people with diabetes have mild NPDR, which usually does not affect their vision. When vision is affected, it is the result of macular edema and/or macular ischemia.

Macular edema is swelling, or thickening, of the macula, a small area in the center of the retina that allows us to see fine details clearly. The swelling is caused by fluid leaking from retinal blood vessels. It is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but even in the worst cases, peripheral (side) vision continues to function. Laser treatment can be used to help control vision loss from macular edema.

Macular ischemia occurs when small blood vessels (capillaries) close. Vision blurs because the macula no longer receives sufficient blood supply to work properly. Unfortunately, there are no effective treatments for macular ischemia.

How is NPDR treated?
NPDR is divided into two types: those that require laser treatment and those that do not. In both cases, the best treatment and prevention is control of your blood sugar. Patients with macular edema caused by leaking blood vessels may require laser treatment to the retina.

Proliferative Diabetic Retinopathy (PDR)

Proliferative diabetic retinopathy is a complication of diabetes caused by changes in the blood vessels of the eye. If you have diabetes, your body does not use and store sugar properly. High blood sugar levels create changes in the veins, arteries and capillaries that carry blood throughout the body. This includes the tiny blood vessels in the retina, the light-sensitive nerve layer that lines the back of the eye.

In PDR, the retinal blood vessels are so damaged they close off. In response, the retina grows new, fragile blood vessels. Unfortunately, these new blood vessels are abnormal and grow on the surface of the retina, so they do not re-supply the retina with blood.

Occasionally, these new blood vessels leak and cause a vitreous hemorrhage. Blood in the vitreous, the clear gel-like substance that fills the inside of the eye, blocks light rays from reaching the retina. A small amount of blood will cause dark floaters, while a large hemorrhage might block all vision, leaving only light and dark perception.

The new blood vessels can also cause scar tissue to grow. The scar tissue shrinks, wrinkling and pulling on the retina and distorting vision. If the pulling is severe, the macula may detach from its normal position and cause vision loss.

How is PDR treated?
All patients with PDR require laser treatment to the retina. Laser surgery may be used to shrink the abnormal blood vessels and reduce the risk of bleeding. The body will usually absorb blood from a vitreous hemorrhage, but that can take days, months or even years. If the vitreous hemorrhage does not clear within a reasonable time, or if a retinal detachment is detected, an operation called a vitrectomy can be performed. During a vitrectomy, the eye surgeon removes the hemorrhage and the abnormal blood vessels that caused the bleeding.

People with PDR sometimes have no symptoms until it is too late to treat them. The retina may be badly injured before there is any change in vision. There is considerable evidence to suggest that rigorous control of blood sugar decreases the chance of developing serious proliferative diabetic retinopathy.

Because PDR often has no symptoms, if you have any form of diabetes you should have your eyes examined regularly by an ophthalmologist.

How is diabetic retinopathy diagnosed?
A medical eye examination or retinal photographs is the only way to find changes inside your eye. If your ophthalmologist finds diabetic retinopathy, he or she may order a special test called a Fluorescein Angiogram to find out if you need laser treatment. In this test a dye is injected in your arm and photos of your eye are taken to detect where fluid is leaking.

If you have diabetes, 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 ophthalmologist regularly. People with diabetes should schedule examinations at least once every two years. Pregnant women with diabetes should schedule an appointment in the first trimester because retinopathy can progress quickly during pregnancy. More frequent medical eye examinations may be necessary after the diagnosis of diabetic retinopathy.