A clinical trial funded by the National Institutes of Health has found that the drug ranibizumab (Lucentis) is highly effective in treating proliferative diabetic retinopathy. The trial, conducted by the Diabetic Retinopathy Clinical Research Network (DRCR.net) compared Lucentis with a type of laser therapy called panretinal or scatter photocoagulation, which has remained the gold standard for proliferative diabetic retinopathy since the mid-1970s. The findings demonstrate the first major therapy advance in nearly 40 years.
Treating abnormal retinal blood vessels with laser therapy became the standard treatment for proliferative diabetic retinopathy after the NEI announced results of the Diabetic Retinopathy Study in 1976. Although laser therapy effectively preserves central vision, it can damage night and side vision; so, researchers have sought therapies that work as well or better than laser but without such side effects.
A complication of diabetes, diabetic retinopathy can damage blood vessels in the light-sensitive retina in the back of the eye. As the disease worsens, blood vessels may swell, become distorted and lose their ability to function properly. Diabetic retinopathy becomes proliferative when lack of blood flow in the retina increases production of a substance called vascular endothelial growth factor, which can stimulate the growth of new, abnormal blood vessels. These new vessels are prone to bleeding into the center of the eye, often requiring a surgical procedure called a vitrectomy to clear the blood. The abnormal blood vessels can also cause scarring and retinal detachment. Lucentis is among several drugs that block the effects of vascular endothelial growth factor.
About 7.7 million U.S. residents have diabetic retinopathy, a leading cause of blindness among working-age Americans. Among these, about 1.5 percent have PDR.
The DRCR.net enrolled 305 participants (394 eyes) with proliferative diabetic retinopathy in one or both eyes at 55 clinical sites across the country. Eyes were assigned randomly to treatment with Lucentis or laser. For participants who enrolled both eyes in the study, one eye was assigned to the laser group and the other was assigned to the Lucentis group. About half of the eyes assigned to the laser group required more than one round of laser treatment. In the other group, Lucentis (0.5 mg/0.05 ml) was given via injections into the eye once per month for three consecutive months, and then as needed until the disease resolved or stabilized.
Because Lucentis is commonly used to treat diabetic macular edema—the build-up of fluid in the central area of the retina—the study permitted the use of Lucentis for diabetic macular edema in the laser group, if necessary. Slightly more than half (53 percent) of eyes in the laser group received Lucentis injections to treat diabetic macular edema. About 6 percent of eyes in the Lucentis group received laser therapy, mostly to treat retinal detachment or bleeding.
At two years, vision in the Lucentis group improved by about half a line on an eye chart compared with virtually no change in the laser group. There was little change in side vision with injection (average worsening of 23 decibels) but a substantial loss of side vision with laser (average worsening of 422 decibels). The vitrectomy rate was lower in the Lucentis group (8 of 191 eyes) than in the laser group (30 of 203 eyes).
Rates of serious systemic adverse events, including cardiac arrest and stroke, were similar between the two groups. One patient in the Lucentis group developed endophthalmitis, an infection in the eye. Other side effects were low, with little difference between treatment groups.
In addition to treating proliferative diabetic retinopathy, the report suggests Lucentis may even help prevent diabetic macular edema from occurring. Among people without diabetic macular edema at the start of the study, only 9 percent of Lucentis-treated eyes developed diabetic macular edema during the study, compared with 28 percent in the laser group. The DRCR.net will continue to follow patients in this study for a total of five years.
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