Apr. 9, 2009 By doing a set of vigorous visual exercises on a computer every day for several months, patients who had gone partially blind as a result of suffering a stroke were able to regain some vision, according to scientists who published their results in the April 1 issue of the Journal of Neuroscience.
Such rigorous visual retraining is not common for people who suffer blindness after a stroke. That’s in contrast to other consequences of stroke, such as speech or movement difficulties, where rehabilitation is common and successful.
“We were very surprised when we saw the results from our first patients,” said Krystel Huxlin, Ph.D., the neuroscientist and associate professor who led the study of seven patients at the University of Rochester Eye Institute. “This is a type of brain damage that clinicians and scientists have long believed you simply can’t recover from. It’s devastating, and patients are usually sent home to somehow deal with it the best they can.”
The results are a cause for hope for patients with vision damage from stroke or other causes, said Huxlin. The work also shows a remarkable capacity for “plasticity” in damaged, adult brains. It shows that the brain can change a great deal in older adults and that some brain regions are capable of covering for other areas that have been damaged.
Huxlin studied seven people who had suffered a stroke that damaged an area of the brain known as the primary visual cortex or V1, which serves as the gateway to the rest of the brain for all the visual information that comes through our eyes. V1 passes visual information along to dozens of other brain areas, which process and make sense of the information, ultimately allowing us to see.
Patients with damage to the primary visual cortex have severely impaired vision – they typically have a difficult or impossible time reading, driving, or getting out to do ordinary chores like grocery shopping. Patients may walk into walls, oftentimes cannot navigate stores without bumping into goods or other people, and they may be completely unaware of cars on the road coming toward them from the left or right.
Depending on where in the brain the stroke occurred, most patients will be blind in one-quarter to one-half of their normal field of view. Everything right or left of center, depending on the side of the stroke, might be gray or dark, for instance.
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