Diabetic Retinopathy: Cause and Treatment.
Limiting the Effects of Diabetes of Your Vision.
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, the seeing part of the eye. This damage is called diabetic retinopathy. There are two kinds:
Nonproliferative diabetic retinopathy (NPDR) happens 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 leakage happens in the macula (the central part of the retina) then vision will be blurred. If the leaks occur on the periphery of the retina, vision may not be affected.
Proliferative diabetic retinopathy (PDR) happens when the retinal blood vessels close, cutting off nutrition to the retinal tissue. Abnormal new blood vessels (called neovascularization) may cause bleeding and form scar tissue. If left untreated, the bleeding (called a vitreous hemorrhage because the blood fills the vitreous cavity inside the eye) and scar tissue can result in blindness. The earlier neovascularization is discovered, the better the chances are that surgery can save vision.
Both types of diabetic retinopathy can happen without a noticeable change in vision. So if you have diabetes, it's critical that you have your retinas examined every six months by a retina specialist.
Diabetes affects 16 million Americans, and is the leading cause of new cases of blindness in people aged 20-74. Each year from 12,000-24,000 people will lose their sight from diabetes. The good news is that vigilant care can markedly reduce the risk of visual complications from diabetes. And for those who do develop problems, new treatment technologies offer hope for saving or recovering some sight.
What is diabetes?
Diabetes is a chronic disease where the body does not produce or properly use insulin, a hormone that helps convert sugar and food into energy. The resulting  biochemical reactions can have a profound impact on the eyes. A high sugar level thickens the lens, which bends the light that filters through. When sugar levels decrease, 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 wrong. For diagnosed diabetics, 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, stopping leaking and preventing 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, new leaks may develop or sealed leaks may reopen, requiring additional laser treatments. That's why it's important to check your vision each day and report any changes or blurriness to your doctor. Newer therapies are also currently under investigation. These include injecting anti-vascular endothelial growth factors and steroids into the eye.
Severe neovascularization (newly formed abnormal blood vessels) resulting from PDR can also be treated with laser surgery. This quick, relatively painless procedure can be done in one of our offices. For patients who don't respond to the laser, a technique called vitrectomy can be performed in the hospital. A vitrectomy removes the vitreous, the jelly-like substance in the center of the eye cavity. The doctor also removes any scar tissue that has formed. Eyesight gradually returns over the next six weeks. Ninety percent of our patients who undergo this procedure enjoy a marked improvement in their vision, with some experiencing as much as an 80% correction.
It used to be that for diabetics with severe vitreous hemorrhaging, laser surgery was traditionally done first. The hemorrhaging was then carefully monitored over the next six months to see if it disappeared. If it didn't disappear, a vitrectomy was 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 an early vitrectomy, performed within one to six months of the hemorrhage, resulted in improved vision.
