Treating diabetic retinopathy

Treatment with the lipid-lowering drug fenofibrate in individuals with type 2 diabetes mellitus reduces the need for laser treatment for diabetic retinopathy, results of a new sub-study show.

One of the many complications of type 2 diabetes mellitus, diabetic retinopathy is a condition in which the inner surface of the back of the eye, called the retina, is progressively damaged.

In its early stages, diabetic retinopathy is often not associated with visual problems and is commonly found on examination within three years of diagnosis of diabetes even in patients with good blood sugar and blood pressure control.

Diabetic retinopathy is responsible for over 80 percent of blindness in patients with diabetes, affecting up to 50 million of the 200 million people with diabetes worldwide.

Blood vessels damaged from diabetic retinopathy can cause vision loss in two ways:

• Fragile, abnormal blood vessels can develop and leak blood into the center of the eye, blurring vision. This is proliferative retinopathy, the fourth and most advanced stage of the disease.

• Fluid can leak into the center of the macula, the part of the eye where sharp, straight-ahead vision occurs. The fluid makes the macula swell, blurring vision.

This condition is called macular edema. It can occur at any stage of diabetic retinopathy, although it is more likely to occur as the disease progresses. About half of the people with proliferative retinopathy also have macular edema.

Fenofibrate is a lipid-lowering drug highly effective at increasing levels of the “good” cholesterol HDL-C and decreasing plasma triglyceride, a predominant feature of type 2 diabetes mellitus.

The sub-study is part of the landmark Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study, which revealed a highly statistically significant 30 percent reduction in the progression of retinopathy, as reflected in the need for laser treatment, among patients assigned to fenofibrate.

The sub-analysis was undertaken to look in further detail at the impact of fenofibrate treatment on the progression of diabetic retinopathy.

Results of the sub-study were published in the November 2007 issue of the medical journal The Lancet.

The sub-study found that overall, with an average follow-up of five years, fenofibrate reduced the frequency of first laser treatment for macular edema by 31 percent and for proliferative retinopathy by 30 percent.

The beneficial effects of fenofibrate were observed both in patients without prior diabetic retinopathy and those with diabetic retinopathy, with benefits seen from eight months onward and increasing throughout the study period.

In addition, fenofibrate significantly reduced the cumulative use of laser therapy by 37 percent overall, 36 percent for macular edema, and 38 percent for proliferative retinopathy.

Proliferative retinopathy is treated with a form of laser surgery called scatter laser treatment, which helps to shrink abnormal blood vessels.

Macular edema is also treated with a form of laser surgery called focal laser treatment, which slows the leakage of fluid and reduces the amount of fluid in the retina.