Scientists have found that laser therapy is equivalent to two different dosages of corticosteroid medications for treating vision loss from the blockage of small veins in the back of the eye, a condition known as branch retinal vein occlusion (BRVO). Furthermore, laser treatment was shown to have fewer complications for patients.
This research was part of the Standard Care vs. Corticosteroid for Retinal Vein Occlusion (SCORE) Study, a phase-III clinical trial conducted at 84 sites and supported by the National Eye Institute (NEI) at the National Institutes of Health.
"The Score study is the first to demonstrate that laser treatment and injections of corticosteroid into the eye have a similar impact on vision loss for patients who have retinal swelling due to branch retinal vein occlusion," said Ingrid U Scott, professor at Penn State College of Medicine and co-chair of the Score study. "However, the lower rate of complications with laser treatment may indicate that it is the best proven treatment option for patients at this time, and that laser represents the benchmark against which other treatments should be compared in future clinical trials."
In the United States, vein occlusion is estimated to be the second most common condition affecting blood vessels in the retina. In BRVO, a blood clot slows or stops circulation in a small vein within the eye's light-sensitive retinal tissue. This may lead to new blood vessel growth and blood vessel leakage, which results in retinal tissue swelling -- a common cause of vision loss from BRVO.
Eye doctors typically treat BRVO with laser therapy applied to the affected retina in a grid pattern. However, some ophthalmologists have treated people who have BRVO using eye injections of an anti-inflammatory corticosteroid called triamcinolone. Because clinical observations suggested a visual benefit, the SCORE study was initiated to compare the safety and effectiveness of standard care laser treatment with two different doses of triamcinolone -- 1 milligram and 4 milligrams. The results appear in the September 2009 issue of Archives of Ophthalmology, published alongside findings from a separate trial within the SCORE study, which looked at blockages in larger retinal veins.
Participants in the study included 411 people with BRVO who were an average of 67 years old. Patients could receive treatment every four months for up to three years. One year after patients began the trial, equal numbers of patients experienced visual improvement in each treatment group. Twenty to 30 percent of patients in each group experienced substantial visual gains of three or more lines on a vision chart-equivalent to identifying letters that were half as small as they could read before treatment.
However, patients who received either dosage of corticosteroid medication were more likely to develop a cataract or have an increase in eye pressure requiring medication than patients who received laser treatment. Between one and two years after treatment was begun, patients who received the 4 milligram dosage were also more likely to undergo cataract surgery.
"These results may have a significant public health impact by providing guidance for clinicians and patients in their selection of a branch retinal vein occlusion treatment," said Frederick L Ferris III, clinical director of the NEI. "Still, better treatments for this condition are needed. This information could guide future clinical trials of new and more effective treatments for BRVO patients."
The Score study was co-chaired by Michael S Ip, associate professor at the University of Wisconsin, Madison, and Ingrid U Scott, MPH, professor at Penn State College of Medicine.
The National Eye Institute (NEI), part of the National Institutes of Health, leads the federal government's research on the visual system and eye diseases. NEI supports basic and clinical science programs that result in the development of sight-saving treatments.