Transcranial magnetic stimulation is a potential treatment for adult amblyopia

Quebec, Canada-There is new evidence that the adult brain is more plastic than originally thought, according to researchers from the McGill Vision Research Department of Ophthalmology, Royal Victoria Hospital, Montreal, Quebec, Canada. The brain regions responsible for vision are capable of adapting in adults and give hope to those with adult amblyopia.

"If not detected early enough-before 7 to 12 years of age-the condition has been considered untreatable because the brain wasn't thought to be plastic enough," said Benjamin Thompson of McGill University. "The main message here is to show that there really is plasticity in the adult visual system. There is real momentum now to find a treatment for adult amblyopia."

Through 15 minutes of repetitive transcranial magnetic stimulation (rTMS) such plasticity can be released temporarily. The treatment works by placing a handheld coil against the scalp that delivers a rapid train of magnetic pulses.

After 15 minutes of rTMS therapy, contrast sensitivity in patients' amblyopic eyes improved for a period of at least 30 minutes. The improvement was measured by showing patients two patches of grating, one with a lot of fine detail and the other with thicker, easier to see lines. After the treatment, people needed less contrast to see those finer details than they had prior to the treatment.

Thompson said that repeated doses of rTMS might allow for longer-lasting effects. The treatment might also prime the brain for training regimes in which adults are asked to perform series of visual tasks. Recent studies have suggested that such perceptual training can improve vision in amblyopic eyes.