SCORE Study Results
Standard Care vs. Corticosteroid for Retinal Vein Occlusion (SCORE) Study Results
Retinal vein occlusion is a condition in which a blood clot slows or stops circulation in a vein within the eye's light-sensitive retinal tissue. If this condition occurs in a large vein, it is known as central retinal vein occlusion (CRVO). If it occurs in a smaller vein, the condition is known as branch retinal vein occlusion (BRVO).
In the United States, retinal vein occlusion is estimated to be the second most common condition affecting blood vessels in the retina. People over the age of 55 who have high blood pressure are at highest risk for this condition. People who have diabetes mellitus are at risk for CRVO, the particular form of the condition that affects large retinal veins.
When a blood clot affects retinal blood flow, the retinal blood vessels may begin to leak fluid. This leakage can result in retinal swelling, which is known as macular edema when it affects the central portion of the retina. Macular edema is the most common cause of vision loss in people who have retinal vein occlusion.
Health care practitioners have typically treated vision loss from macular edema due to BRVO with laser therapy, which is applied to the affected retina in a grid pattern. No proven treatment has existed for vision loss from macular edema due to CRVO.
However, some ophthalmologists have treated patients using eye injections of small amounts of an anti-inflammatory corticosteroid medication called triamcinolone. Corticosteroids block the production of immune system compounds that trigger allergic reactions and inflammation. They have been used to treat a variety of conditions, ranging from brain tumors to arthritis. Corticosteroid medications are not the same as performance-enhancing anabolic steroids used by some athletes.
Some ophthalmologists reported that patients with macular edema due to retinal vein occlusions had visual benefits when they were treated with injections of triamcinolone. However, the safety and effectiveness of this corticosteroid medication had not been tested in a clinical trial.
The SCORE Study
To evaluate the clinical benefits of triamcinolone for treating macular edema associated with vein occlusion, researchers organized a multi-center clinical trial known as the Standard Care vs. Corticosteroid for Retinal Vein Occlusion (SCORE) study. This study, conducted at 84 clinics across the country, was sponsored by the National Eye Institute, part of the federal government's National Institutes of Health.
SCORE researchers divided the study into two separate clinical trials. One trial compared the safety and effectiveness of clinical observation with corticosteroid eye injections to treat vision loss from macular edema associated with CRVO. The other trial compared the safety and effectiveness of grid laser treatment with corticosteroid eye injections to treat vision loss from macular edema associated with BRVO. The primary goal of both trials was to compare the visual acuity of patients among the treatment groups at one year after patients enrolled in the study.
Within each trial, scientists divided the participants into three groups: one group received the standard clinical care for the condition and the other two groups received one of two doses of corticosteroid medication. Researchers selected 4 milligrams as one of the doses because, at the time that the study began, it was the most common dose used by doctors in the clinic. They selected 1 milligram as the other dose because it was likely to be the lowest possible dose that would stimulate a response in the eye. Participants could receive treatment upon enrollment in the trial, as well as every four months subsequently for up to three years, based on the state of their disease.
SCORE CRVO Trial Results
The SCORE CRVO trial included 271 people who were an average age of 68. Seventy-three percent of patients with CRVO had high blood pressure and 23 percent had diabetes. Patients in the corticosteroid medication groups received an average of two injections in the first 12 months of the study.
After one year, 27 percent of patients in the 1 milligram group and 26 percent of patients in the 4 milligram group experienced a substantial visual gain of three or more lines on a vision chart-equivalent to identifying letters that were half as small as they could read before treatment. Only 7 percent of patients in the observation group experienced a similar visual gain. Therefore, patients in the corticosteroid treatment groups were five times more likely to have a substantial visual gain at one year. These results appeared to last up to two years, though the two-year results included a smaller number of patients.
However, participants who received the 4 milligram dose had the highest rates of cataract formation, cataract surgery, and elevated pressure within the eye, indicating that the 1 milligram dose is safer for patients.
SCORE BRVO Trial Results
The SCORE BRVO trial included 411 people who were an average age of 67. Seventy percent of patients with BRVO had high blood pressure. Participants in the grid laser treatment group received an average of 1.5 treatments in the first 12 months of the study, and participants in the corticosteroid medication groups received an average of two injections in the first 12 months.
After one year, 29 percent of patients in the laser treatment group, 26 percent of patients in the 1 milligram corticosteroid injection group, and 27 percent of patients in the 4 milligram injection group experienced a substantial visual gain of three or more lines on a vision chart. These results appeared to last up to three years, though the three-year results included a smaller number of patients.
However, patients who received either dose of corticosteroid medication were more likely to develop a cataract or experience elevated pressure within the eye than patients who received laser treatment. Also, between one and two years after enrollment in the study, patients in the 4 milligram group underwent more cataract surgeries than patients in the other groups. Therefore, laser treatment may have fewer negative side effects for patients.
Impact on Clinical Practice
Through the SCORE CRVO trial, scientists identified the first long-term, effective treatment to improve vision and reduce vision loss associated with macular edema due to CRVO. A large clinical trial had never before shown that patients with CRVO could experience a visual improvement with treatment. Therefore, clinicians may now offer people who have macular edema associated with CRVO a low-dose corticosteroid injection that could increase their chance of visual improvement.
The SCORE BRVO trial was the first large, long-term clinical trial to show that laser treatment and eye injections of corticosteroids have a similar impact on vision for patients who have macular edema due to BRVO. However, laser treatment may still remain the best proven treatment option because it is associated with fewer complications for patients. In future clinical trials, laser may also serve as the best benchmark with which other BRVO treatments should be compared.