Magnetic Pulses to Brain Improve Lazy Eye in Adults

By Ed Edelson
HealthDay Reporter
Friday, July 18, 2008; 3:00 PM

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FRIDAY, July 18 (HealthDay News) -- Correcting lazy eye in adults is supposed to be impossible, but researchers report they have been able to do that -- at least partially and temporarily -- by beaming magnetic pulses into the brain.

Someone with lazy eye -- ophthalmologists call it amblyopia -- has poor vision because one eye is weaker than the other. Early treatment often has a child wearing a patch over the strong eye to strengthen the weaker one, but the problem has been thought to be untreatable in adulthood. Most of the estimated 6 million Americans with amblyopia are adults.

"We know now that visual loss is caused by poor processing in the cortex," said Benjamin Thompson, a postdoctoral fellow in the ophthalmology department at McGill University in Canada, and a member of the group reporting on the new method in the July 22 issue of Current Biology. "Treatment usually addresses the problem with the eye, not with the cortex."

The study was prompted in part by research at a number of institutions showing that changes can occur in the adult brain, which until recently was thought to be impossible.

The cortex is a vital part of the brain, involved in vision among other functions. Work by other researchers has shown that transcranial magnetic stimulation, in which a rapid train of magnetic impulses is delivered to the brain through a hand-held coil placed on the scalp, has been effective in stroke rehabilitation and is being tested against depression.

When it was tried on nine adults with amblyopia, 15 minutes of magnetic stimulation improved the sensitivity of the weaker eye temporarily, Thompson said. In visual tests, they were able to see finer details than before the treatment.

"We were surprised by how well it worked," he said. "Vision in the amblyopic eye improved for at least 20 minutes after transcranial magnetic stimulation."

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."