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Diabetic Retinopathy

The Problem:

When diabetes is uncontrolled, chronic high blood sugar levels can damage the blood vessels that feed the retina of the eye. In nonproliferative diabetic retinopathy (NPDR), an early stage of diabetic eye disease, the blood vessels may leak fluid. This may cause the retina to swell and vision to blur, a condition called diabetic macular edema. In what's known as advanced or proliferative diabetic retinopathy (PDR), abnormal new blood vessels grow on the surface of the retina. The abnormal blood vessels don't supply the retina with normal blood flow, and in addition may eventually pull on the retina and cause detachment.

Diabetic retinopathy is the leading cause of new cases of blindness, accounting for about 8,000 cases each year. It's the most common and serious threat to vision that people with diabetes face. Nearly half of all people with diabetes eventually develop some degree of diabetic retinopathy. It usually occurs in both eyes. There may be no early signs of the disease. More advanced cases may be signaled by floaters, blurred vision, eye pain, or gradual vision loss.

Experts say the rate of diabetic retinopathy is likely to get worse because the number of people with diabetes is increasing. About 16 million people have diabetes and many don't know it. In one recent National Institutes of Health study of Mexican-Americans over age 40, 23 percent of those who didn't know they had diabetes also had early to moderate diabetic retinopathy.

Risk Factors:

Uncontrolled diabetes is the prime risk factor for retinopathy. Diabetic retinopathy can usually be managed with a combination of tight blood sugar control, appropriate exercise and diet, and early detection. People who are diagnosed with diabetes before age 30 should begin having dilated exams every year beginning five years after diagnosis. All others with diabetes should have an eye exam every year. A recent study in the AAO's journal Ophthalmology showed that more than one-third of Americans with diabetes don't get a yearly dilated exam as recommended, putting them at risk for vision loss.

Treatment:

Some cases of diabetic retinopathy can be treated with laser surgery that aims a strong beam of light onto the retina to shrink or seal leaking or abnormal vessels. But it can't restore vision already lost, which is why early detection is important. In some advanced cases of PDR, a vitrectomy is recommended, in which the surgeon removes the vitreous portion of the eye and replaces it with a clear solution.

Josephine Grant, 54, a former cafeteria worker from Gaithersburg, Md., says she had diabetes for several years and then experienced major vision loss seven years ago because of diabetic retinopathy. She is blind in her right eye, and can see a little bit with the left eye. Unfortunately, Grant came to treatment with an advanced form of the disease, which made her prognosis poor, says T. S. Melki, M.D., the Maryland ophthalmologist who performed Grant's surgeries.

If laser surgery is done in time, he says, the disease can be stopped or slowed. Melki says hundreds of patients with diabetes come see him regularly, sometimes as frequently as every four to five months, so that the level of diabetic retinopathy can be followed closely. "If a patient has minimal disease then the follow-up is less frequent," Melki says. "There are some patients we refer to as 'The Golden Club,' who have had diabetes for over 20 years with no effect on the eye," he says. "So it can be done."

Retinal Detachment

The retina is the light-sensitive layer of tissue that lines the inside of the back of the eye and sends visual messages to the brain. If the retina detaches from its normal position, permanent vision loss can result.

While anyone can experience retinal detachment, head or eye injuries and certain eye conditions increase the risk. These include myopia, commonly known as nearsightedness, and posterior vitreous detachment, which occurs when the vitreous (the jelly-like fluid in the eye) breaks away from the back of the eye. The most common symptom of a posterior vitreous detachment is a condition called floaters, specks or strands that appear to float in the field of vision. Sometimes when the vitreous breaks away it can tear the retina, which can lead to retinal detachment.

Symptoms of retinal detachment include seeing floaters, flashes of light, or the appearance of a curtain over the field of vision. It's important to see an eye-care professional immediately if you experience these symptoms because early treatment is critical for restoring vision.

Small holes and tears in the retina may be treated in a doctor's office with laser surgery, which uses tiny burns to seal the retina back into place. Another treatment, cryopexy, freezes the area around the hole in the retina. Retinal detachments may require surgical treatment to reattach the retina and a hospital stay.

Tags: Eyes and Vision, Diabetes

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