Lloyd Paul Aiello, M.D., Ph.D. Professor of Ophthalmology at Harvard Medical School, Vice Chair for Centers of Excellence at Harvard Department of Ophthalmology, Director of the Beetham Eye Institute of the Joslin Diabetes Center (JDC), Medical Director of Ophthalmology and Brigham & Women’s Hospital, Head of the Section of Eye Research (JDC), Vice President of Ophthalmology at JDC, and Founding Chair of the National Eye Institute Diabetic Retinopathy Clinical Research Network.
About half of all people with diabetes eventually develop some problem with their eyes or vision. They are more likely than others to get cataracts or glaucoma. The most feared eye complication, however, is diabetic retinopathy, which is relatively common and potentially sight threatening. But there’s a lot we can do to preserve vision, even for those with diabetic retinopathy.
People with diabetes can help preserve their vision—as well as reduce many of the complications associated with diabetes—by controlling their blood glucose, blood pressure and cholesterol and triglyceride (“lipid”) levels. Even if they do not yet have diabetic eye complications, they need to have routine lifelong eye checkups at least once a year to catch any problems that start to develop.
Annual examinations are critical because a person with eye complications often does not experience any symptoms that indicate damage until it’s too late to undo the damage. The presence of eye disease usually requires more frequent eye examinations.
Don’t Wait for Symptoms
Diabetic retinopathy occurs when the tiny blood vessels inside the retina—the tissue at the back of the eye that sends images to the brain—become damaged. There are usually no symptoms at this early “nonproliferative” stage. Essentially all people with diabetes will eventually develop some changes in the retina, usually within 20 years of diabetes onset.
In two-thirds of cases, this type of retinopathy progresses to the “proliferative stage,” although research shows that intensive glucose and blood pressure control can delay the onset of disease and slow its progression. In the proliferative stage, the retina forms new vessels in an attempt to circumvent nonfunctioning blood vessels. These new vessels, however, are abnormal, fragile and bleed readily.
If the condition is treated with laser photocoagulation when the abnormal vessels are in their early stages, severe vision loss can be prevented in about 95 percent of cases. The laser scars the retina, causing the vessels to regress, which prevents subsequent bleeding and pulling on the retina. Since the laser destroys some areas of the retina, there may be side effects of treatment—such as reduced side or night vision—but central vision is retained far better than if the patient receives no treatment at all.
Diabetic macular edema, however, is a different story. Diabetes can cause the retinal vessels to leak, leading to swelling of the retina. If this swelling occurs in the small area in the center of the retina called the macula, the condition is called macular edema. Vision can decline because this area of the retina is responsible for central vision. Laser treatment is also used for this condition but is less successful than when used for new vessels. Treatment reduces the chance of vision worsening by only half, and, even when successful, is usually not associated with improved vision.
This is why everyone with diabetes should get annual eye checks and keep blood glucose, blood pressure and cholesterol in good control.
Page last updated: March 29, 2017