It was admittedly a small trial, but "one of the issues we were addressing was whether amblyopia could be treated in adults," Thompson said. "The adult brain doesn't have the same capacity for change as in children."
There are two ways to exploit the finding, and the McGill group plans to try both of them, Thomson said. One route is to use multiple bouts of transcranial stimulation.
"We've only tried a single dose so far in our study," he said. "Now, we can look at the effect of repeated doses. In depression, it seems they can have an effect."
The other possibility is to use magnetic stimulation to prime the brain for a rehabilitation program, a training regimen in which adults are asked to perform a series of visual tasks. Recent studies have indicated that such a perceptual training program can improve vision in amblyopic eyes.
"We will also have a parallel project, a training regime with stimuli to both eyes, higher-contrast stimuli to the amblyopic eye," Thompson said. "We hope that repeated exposure will bring improvement."
The report is one of several indicating that the adult brain has more capacity for change than had been thought, said Dr. Robert Cykiert, a clinical associate professor of ophthalmology at New York University.
Lazy eye occurs because the proper connections between the eye and the cortex do not form early in life, Cykiert explained. "We thought that if the connections do not form by age 10 or so, it is too late."
The McGill study indicates otherwise, he noted. "The study has very preliminary results, but obviously this may lead to other related or similar treatments that may have a more lasting effect," Cykiert said. "What we might be able to do is to allow people with lazy eye to have treatments that stimulate that part of the brain."
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