Diabetes

The retina, a tissue that lines the back of the eye, is the part of the eye that senses light and sends visual information to the brain. The retina is supplied by blood vessels, arteries and veins which carry vital nutrients within the blood stream. The retinal blood vessels may be affected by diabetes just as in other parts of the body. It is primarily these changes in the blood vessels that lead to problems in the eyes of people with diabetes.

Diabetic changes in the blood vessels impair their ability to supply the retina with nutrients which may cause portions of the retina to become starved for oxygen. These areas of the retina, which are deprived of their blood supply, call out for new blood vessels to feed them. The new blood vessels are abnormal and are called neovascularization. They grow along the surface of the retina in a membrane that may contract, causing the blood vessels to tear and bleed into the eye. When this happens, the vision will appear dark in the region where the blood accumulates. If the blood does not clear, it may form membranes within the eye that can detach the retina from the back of the eye. A retinal detachment will also cause a dark spot in the vision, and may cause permanent damage to the retina if not repaired by an ophthalmologist. It is important to note that neovascularization may occur without any noticeable change in your vision.

Diabetes may also cause the blood vessels to become leaky. The fluid which leaks from the vessels may then accumulate in the macula, the central visual area of the retina, and cause distorted or blurred vision. This is known as diabetic macular edemaand is a leading cause of decreased vision in adult-onset diabetics.

People with diabetes are also more likely to develop cataracts at an earlier age. A cataract occurs from clouding of the normally clear lens which focuses light onto the retina. Cataracts probably form sooner in diabetics due to fluctuations in blood sugar levels, which draw water into the lens, making vision cloudy.

The eye doctor will dilate your eyes so that the retina can be examined for signs of diabetic eye disease. Changes in the retina, such as blood spots, exudates, and cotton-wool spots, are related to the vascular effects of diabetes and are known asnonproliferation diabetic retinopathy. If there are abnormal blood vessels growing on the retina, then proliferative diabetic retinopathy is present, and there is a significant risk for bleeding into the eye. The macula will also be carefully examined to detect any diabetic macular edema which may or may not be causing decreased vision.

Numerous studies have been completed to determine the natural course of diabetic eye disease and to evaluate different methods of treatment. Currently, lasers are used to treat proliferative diabetic retinopathy as well as diabetic macular edema. The type of laser surgery which is done for proliferative diabetic retinopathy is known as pan retinal photocoagulation. The goal of this laser surgery is to destroy all of the areas of the retina where the blood vessels have closed and where the new blood vessels are needed. When these areas are treated, the retina stops making new blood vessels and the ones that are already present tend to shrink away. This can present the complications of bleeding into the eye (vitreous hemorrhage) and retinal detachment from membrane formation. The Diabetic Retinopathy Study showed that the risk of severe visual loss from complications of proliferative diabetic retinopathy could be reduced by greater than 50 percent by pan retinal photocoagulation laser treatment.

The laser can also be used to treat leaking blood vessels that are causing diabetic macular edema. A fluorescein angiogrammay be ordered by the doctor in order to find the areas of leakage so that they may be treated with laser.

The most important measure in preventing complications from diabetic eye disease is to see your eye doctor regularly. People with adult onset diabetes should be seen by an eye doctor shortly after diagnosis, and then annually for a diabetic eye exam. Juvenile-onset diabetics should be seen annually beginning five years after the onset of diabetes. Women with diabetes who become pregnant should be seen during each trimester and three months after delivery as diabetic retinopathy can accelerate during pregnancy.

To detect treatable diabetic eye disease before complications develop, annual diabetic eye exams must occur. The doctor may recommend more frequent visits if there are changes in the retina which need to be watched more closely.

Patients should also regularly see a physician who can help control diabetes. Strict control of blood sugar levels has been shown to decrease the risk of progression of non-proliferative diabetic retinopathy to proliferative diabetic retinopathy.

To learn more about diabetes, including diabetic eye disease, please visit the American Diabetes Association online.