UW Health Ophthalmologist Studies Stroke in the Eye
MADISON - A large clinical trial led by a University of Wisconsin-Madison physician has identified the first long-term, effective treatment to improve vision and reduce vision loss associated with blockage of large veins in the eye.
The study is likely to lead to immediate changes in the way eye doctors treat the second-most common cause of vision loss.
"This is really good news because we're never had an effective treatment for central vein retinal occlusion and for many years we've had to tell patients we can't do anything about it," says Dr. Michael S. Ip, associate professor of ophthalmology and visual sciences at the UW School of Medicine and Public Health and chair of the nationwide study.
The Standard Care vs. Corticosteroid for Retinal Vein Occlusion (SCORE) study, conducted at 84 clinical sites, found that eye injections of a corticosteroid medication could reduce vision loss related to the blockage of major blood vessels within the eye, a condition known as central retinal vein occlusion (CRVO). Treated patients were also five times more likely to gain vision after one year than patients who were under observation.
A second part of the study, also co-chaired by Dr. Ip, compared laser treatment versus corticosteroid injections for branch retinal vein occlusion (BRVO) and concluded that laser treatment leads to better long-term results when blood clots block the smaller veins in the back of the eyes.
Both studies are being published today in the Archives of Ophthalmology, along with an accompanying editorial saying "these well-designed studies will influence future research, treatment paradigms and clinical practice patterns for years to come."
Ip, a UW Health ophthalmologist, described vein occlusion as the equivalent of "a stroke in the eye." It occurs when a blood clot slows or stops circulation in the eye's light-sensitive retinal tissue, leading to reduced retinal circulation, blood vessel leakage, retinal tissue swelling - and, ultimately, vision loss.
In the United States, vein occlusion is estimated to be the second-most common condition affecting blood vessels after diabetic retinopathy. There are 160,000 new cases each year, about 80 percent occurring in the branch veins (BRVO) and 20 percent in the central vein (CRVO).
Until now, there has been no proven, effective way to treat CRVO. However, some ophthalmologists had reported good results treating patients with eye injections of an anti-inflammatory corticosteroid called triamcinolone. The SCORE study was the first clinical trial to compare the safety and effectiveness of standard-care observation with two different dosages of triamcinolone: 1 milligram and 4 milligrams.
"We found that the lower dose was just as effective and had significantly lower side effects,'' Ip says.
Study participants included 271 CRVO patients who were an average of 68 years old. Patients in the treatment group could receive a maximum of three corticosteroid injections every year for up to three years, based on the state of their disease.
At one year, patients who received either dose of the corticosteroid medication were five times more likely than those who did not receive treatment to experience 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. However, patients who received the lower dose had fewer side effects such as increased eye pressure and cataract formation.
For patients who suffer the more common BRVO or small-vein blockage, the results and treatment recommendations are different.
The study found that while both laser therapy and corticosteroid injections worked to improve vision, laser treatment had fewer complications and better long-term results. Eye doctors typically treat BRVO with laser therapy applied to the affected retina in a grid pattern.
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.
"Laser treatment (of BRVO) proved more efficacious over time, and had zero side effects,'' says Ip.
Two of Ip's colleagues in the Department of Ophthalmology and Visual Sciences who took part in the SCORE study were Dr. Michael Altaweel, who headed the local patient study group, and Dr. Barb Blodi, who interpreted the images of the treated eyes from all 712 participants at the UW Fundus Photograph Reading Center located in Research Park.
The SCORE study was co-chaired by Dr. Ingrid U. Scott, professor at Penn State College of Medicine.
Date Published: 09/14/2009