Diabetic Retinopathy

What is diabetic retinopathy?

The chemical changes caused by diabetes can damage blood vessels throughout the body, including the fine blood vessels in the retina, or the seeing part of the eye. This damage is called diabetic retinopathy of which there are two kinds:

Nonproliferative diabetic retinopathy (NPDR) occurs when the retinal blood vessels start to leak, causing blood or fluid to seep into the retina. The retina becomes thick and swollen and does not work correctly. If the leaking happens in the macula, (the central part of the retina), vision will be blurred. If the leaks occur on the periphery of the retina, there may be no impact on vision.

Proliferative diabetic retinopathy (PDR) occurs when the retinal blood vessels close, cutting off nutrition to the retinal tissue. Abnormal new blood vessels, called neovascularization, may form and cause bleeding and scar tissue. The bleeding (called vitreous hemorrhage because the blood fills up the vitreous cavity inside the eye) and scar tissue can result in blindness if not treated. The earlier neovascularization is discovered, the better the chance that surgery can save vision. Both types of diabetic retinopathy may occur without a noticeable change in vision. It is therefore imperative, if you have diabetes, to have your retinas examined every six months by an eye specialist.

Diabetes affects 16 million Americans and is the leading cause of new cases of blindness in people ages 20­74. Each year from 12,000-24,000 people will lose their sight from the disease. Vigilant care, however, can markedly reduce the risk of visual complications for diabetics. And for those that do develop problems, new treatment technology offers hope for saving or recovering some sight.

What is diabetes?
Diabetes is a chronic disease in which the body does not produce or properly use insulin, a hormone that helps convert sugar and food into energy. The biochemical reactions that occur because the body doesn't have the proper amounts of blood sugar can have a profound impact on the eyes. A high sugar level thickens the lens and bends the light that filters through. When sugar levels decrease, just the opposite happens. The constant thickening and thinning of the lens due to dramatic swings in blood sugar levels leads to blurry vision. For people who are unaware that they have diabetes, blurry vision is often the first signal that something is amiss. For those who know they are diabetic, blurry vision is a warning to get blood sugar levels under control through a combination of diet, exercise and medication.

How is diabetic retinopathy treated?

For patients with NPDR, laser surgery can seal the blood vessels to stop leaking and prevent further vision loss. Your doctor will perform a test called fluorescein angiography to pinpoint the exact locations of the leaks. In some cases, the diagnosis and the laser treatment can be performed in the same visit. Even after surgery is done, new leaks may develop or sealed leaks may reopen requiring additional laser treatments. That is why it is very important to check your vision each day and report any changes or blurriness to your doctor.

Severe neovascularization resulting from PDR can also be treated with laser surgery to prevent vision loss. This is done in one of our offices and takes only a short time, usually not causing any pain. For patients who don't respond to the laser, a relatively new technique called vitrectomy can be performed in the hospital. A vitrectomy removes the jelly-like substance in the center of the eye cavity called the vitreous. The vitreous is where the abnormal blood vessels and hemorrhaging are located, so the vessels and blood are also removed. Then the doctor will remove any scar tissue that has formed. Eyesight gradually returns over the following six weeks. Ninety percent of our patients undergoing this procedure enjoy a marked improvement in their vision, some as much as an 80 percent correction.

In diabetics with severe vitreous hemorrhaging, laser surgery was traditionally done first, with the hemorrhaging carefully monitored over the next six months to see if it disappeared. If it didn't disappear, then a vitrectomy would be performed. A recent study conducted by Dr. Liggett and his colleagues at the Yale Eye Center concluded that this extended observation period is unnecessary and may even be detrimental to the health of the eye. The study, published in Ophthalmology 102(8), found that early vitrectomy, performed within one to six months of the hemorrhage, yields improved visual acuity and anatomic success for these patients.