TORONTO -- Patching has long been used to treat a lazy eye in children, although the therapy has limited success and doesn't work at all in adults with the condition formally known as amblyopia.
Now researchers at McGill University in Montreal are testing an innovative means of improving visual function in adults with lazy eye -- a puzzle video game that forces both eyes to work together to overcome the common condition.
In a study published Monday in the journal Current Biology, the researchers compared the use of the online video game Tetris with patching, a treatment in which the "good" eye is covered for a lengthy period of time. The idea is to make the weak eye do all the visual work in the hope of strengthening its acuity.
The patients treated using Tetris showed a four-fold improvement in vision in their lazy eye compared with those who were patched, said ophthalmologist Dr. Robert Hess, director of vision research at the McGill University Health Centre and principal investigator of the study.
Tetris is an early video game that involves manipulating shapes made of small squares -- moving them side to side or rotating them -- as they fall to the bottom of a background grid of same-sized squares. The goal is to connect different-shaped blocks, putting them together in an integrated whole before they fall to the bottom.
"The game itself is sort of incidental in a way," Hess explained Monday from Montreal. "It just provides us with a platform to administer this training that we need to do in a way that's enjoyable.
"The game itself is not so important as the principle behind how we manipulate the game to do some good."
About three to four per cent of the population develops a lazy eye in very early childhood, making it the most common cause of vision problems in children. A lazy eye, which is unable to see details in sharp focus, has a number of causes, including having misaligned eyes (being cross-eyed) or having a congenital cataract that clouds the lens.
The eye itself is usually otherwise normal, as is the optic nerve that transfers visual information to the brain. The problem is with the brain's visual cortex, which has learned to suppress the information from the weak eye in favour of the other eye, leading to single-eye or monocular vision.
"We know the eye itself is fine; we know it's all in the brain," said Hess. "We're now beginning to realize that it's just the software that's gone wrong."
Typically, people with amblyopia also have little or no 3D vision, because it takes both eyes working together to provide depth of vision.
-- The Canadian Press