Protecting Your Vision If You Have Diabetes
Researchers have made significant advances in diagnosing and treating diabetic retinopathy, one of the most serious complications of diabetes. Even so, diabetic retinopathy, which is caused by damage to the tiny blood vessels that supply the retina, remains a leading cause of new cases of blindness among adults in the developed world.
In people with diabetes, over time, elevated blood glucose levels can cause small areas of balloon-like swelling (microaneurysms) to form in the blood vessels of the retina, which may leak fluid. As the damage progresses, these blood vessels lose their ability to transport blood. In severe diabetic retinopathy, the damaged area may begin to secrete growth factors that signal the retina to grow new blood vessels. As these fragile vessels proliferate, they may leak and bleed, causing more vision loss.
Fortunately, there is plenty that individuals with diabetes can do to protect their vision, even if they already have early signs of diabetic retinopathy. In a position statement that was published last year in the journal Diabetes Care, the American Diabetes Association (ADA) offered updated guidelines highlighting four key ways in which people with diabetes can halt or slow the progression of this debilitating condition.
Maintain optimum blood sugar control
The more tightly that blood glucose levels are kept within the normal range, studies have shown, the lower the risk of diabetic retinopathy.
In one of the first long-term studies to examine complications from diabetes, researchers with the United Kingdom Prospective Diabetes Study (UKPDS) followed 3,687 people newly diagnosed with type 2 diabetes for an average of 10 years. The results indicated that complications from the disease could be reduced by improving blood glucose control. The data showed that a decrease of one percentage point in A1c levels (from 9 percent to 8 percent, for example) was associated with a 35 percent reduction in microvascular complications, including diabetic retinopathy. Overall, individuals who received intensive therapy to rein in blood glucose levels had a 25 percent lower risk of developing retinopathy and a related form of nerve damage called neuropathy, compared with those who received less aggressive treatment for their diabetes.
Similar findings resulted from the Diabetes Control and Complications Trial (DCCT), another long-term study evaluating the effects of intensive blood sugar control versus what was at the time "standard control" of blood sugar levels, though it studied patients with type 1 diabetes. The DCCT, similar to the UKPDS, found that changes in A1c had large effects on the progression of diabetic retinopathy.
Rein in high blood pressure
Like elevated glucose levels, high blood pressure can damage tiny blood vessels that supply the retina. Research has shown that controlling hypertension can lower the danger of diabetic retinopathy. The landmark UKPDS, for example, found that lowering systolic blood pressure from 154 mm Hg to 144 mm Hg reduced the risk of microvascular damage, including diabetic retinopathy and a related condition called diabetic macular edema, by 37 percent.
Although bringing blood pressure numbers even lower has been shown to provide additional protection against heart disease, the more aggressive treatment does not seem necessary for reducing the risk of diabetic retinopathy. Findings from the ACCORD Eye Study, which tracked signs of diabetic retinopathy progression in 2,856 patients over four years, showed no added benefit with regard to retinopathy for individuals who lowered systolic pressure from 140 mm Hg to 120 mm Hg.
Treat elevated triglycerides
High triglyceride levels, which are known to increase the risk of developing heart disease, may also play a role in diabetic retinopathy. Studies have found that a drug called fenofibrate, which reduces levels of serum triglycerides, also slows the progression of retinopathy. In the ACCORD study, a 160-mg dose of fenofibrate reduced the risk of diabetic retinopathy progression by one third. That finding is important because fenofibrate is rarely prescribed for heart patients, since the drug has not been shown to reduce cardiovascular risk. But according to the ADA position statement, evidence that fenofibrate helps protect vision in individuals with diabetes is sufficient "to consider this treatment for people affected with diabetic retinopathy."
Get regular eye exams
By controlling blood glucose levels, blood pressure, and triglycerides, individuals who have diabetes can significantly reduce their risk of diabetic retinopathy. The first step in managing and preventing diabetic eye disease is an initial screening by an ophthalmologist or optometrist to check whether any early signs of retinopathy are present. The ADA recommends an eye examination at the time of diagnosis for individuals who have type 2 diabetes. For individuals with type 1 diabetes, which is usually diagnosed early in life, an eye examination should be performed within five years of the onset of diabetes. Women with preexisting diabetes who are planning to become pregnant or who are pregnant should have an eye exam before pregnancy or in the first trimester.
If there isn't any sign of retinopathy, having eye examinations every two years, as opposed to annually, may be considered, according to the ADA. If there is evidence of any level of retinopathy, eyes should be examined at least once a year. More frequent eye examinations may be necessary in cases where retinopathy is progressing or vision is declining.