Diabetes is the leading cause of blindness in adults in the United States. Although eye problems can be a concern for people with diabetes, most diabetics have only minor eye disorders. The goal is to keep eye problems to a minimum and treat them before they become serious, says Karen Gehrs, M.D., UI Hospitals and Clinics ophthalmologist.
Diabetes affects the eyes by causing damage to the circulation in the retina. "The tiniest blood vessels, called capillaries, are damaged first," Gehrs says. "The damage occurs slowly and is spread out over a large area so damage can be occurring over years without causing symptoms."
Diabetic retinopathy describes the damage in the retina caused by poor circulation. "High blood sugar and other metabolic changes associated with diabetes causes damage to the capillaries, which supply oxygen and other nutrients to the retina," she says. "When capillaries are damaged, the circulation is compromised."
Tissue with compromised circulation can develop several responses:
- Hemorrhage
- Swelling
- Growth of abnormal blood vessels
- Collections of fatty deposits called exudates
All of these findings can cause vision to be worse. Over time some of the problems can cause the retina to detach and can even cause loss of the eye in severe cases.
Diabetic retinopathy is diagnosed by having a dilated eye examination. There are special cameras that can take photographs of the eyes without dilation that are pretty good at detecting retinopathy. For someone at low risk of retinopathy (that is, someone with good diabetes control and no vision problems) the cameras can be very useful in screening large populations.
"The cameras do not pick up other eye problems, however, so they do not take the place of a complete eye exam. Until more studies are done validating the cameras, the gold standard is still a dilated eye examination," Gehrs says. "Certainly, anyone who has had prior laser treatments or who has problems with their vision should have a complete dilated eye examination."
Not all stages of retinopathy need treatment, Gehrs says. "Early retinopathy does not require treatment--just monitoring. Once someone has developed swelling near their central vision (called Diabetic Macualar Edema or DME) or new blood vessels (called Proliferative Diabetic Retinopathy or PDR) then laser treatment is the standard treatment.
"In some patients, laser is not sufficient to treat the problem and has to be combined with a surgery called vitrectomy. There are also medications under study that may help treat diabetic retinopathy better."
The medications being studied are some that are taken in a pill or shot form and some that are injected directly into the eye. Some doctors are already injecting medications in the eye to treat diabetic eye disease, but the studies proving these drugs work when injected in the eye are not yet finished, so injecting drugs in the eye to treat diabetic eye disease is considered "off label" treatment.
"Complications of diabetic retinopathy include vision loss ranging from mild to total blindness. Total blindness is rare today with modern treatments, but patients and doctors need to be proactive to keep the vision as good as possible," she says.
In most cases, eye problems in diabetics can be prevented. "Prevention starts with excellent diabetes, high blood pressure, and cholesterol management. Studies show that keeping all of these conditions as normal as possible greatly lowers the risk of developing retinopathy or of having it get worse.
"I have many patients whose retinopathy has improved when they improved their diabetes, blood pressure, and cholesterol control. So it's never too late to get in good control. Once someone has treatable diabetic retinopathy, instituting laser treatment (or others that are being developed) can prevent significant vision loss in most cases.
"There are always exceptions--some patients have such poor circulation when they come to medical attention that nothing will help--like stopping a runaway freight train. That is why it is so important that patients with diabetes establish their eye care as soon as they find out they have diabetes and then have regular eye care," she says.
A person with diabetes should see their ophthalmologist at least once a year. What the eye doctor sees during the first exam will determine how soon the patient should be seen again, and they should discuss that with their eye doctor, Gehrs says. Anyone, diabetic or not, should see their eye doctor immediately if they experience a sudden problem with vision in either eye, new floaters, eye redness, or eye pain.
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