Stroke patients with vision loss are often told that there is nothing they can do to improve or regain their vision. But a new study may offer hope to stroke patients in retrieving vision. The findings of the study are published in the journal Brain. The Rochester team found that survivors of occipital strokes--strokes that occur in the occipital lobe of the brain and affect the ability to see--may retain some visual capabilities immediately after the stroke, but these abilities diminish and eventually disappear permanently after approximately six months. By capitalizing on this initial preserved vision, early vision training interventions can help stroke patients recover more of their vision loss than if training is administered after six months.
‘After primary visual cortex damage in stroke patients, rather than waiting for the vision to stabilize, early training interventions may be key to maximize the system's potential for recovery.’
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"One of our key findings, which has never been reported before, is that an occipital stroke that damages the visual cortex causes gradual degeneration of visual structures all the way back to the eyes," says Krystel Huxlin, the James V. Aquavella, MD Professor in Ophthalmology at the University of Rochester's Flaum Eye Institute.The Rochester research team--including Elizabeth Saionz, a Ph.D. candidate in Huxlin's lab and the first author of the paper; Duje Tadin, professor and chair of the Department of Brain and Cognitive Sciences; and Michael Melnick, a postdoctoral associate in Tadin and Huxlin's labs--additionally discovered that early intervention in the form of visual training appears to stop the gradual loss of visual processing that stroke victims may experience.
Vision stroke rehabilitation remains a developing field, and previous studies and trials of experimental therapies have focused on patients with chronic vision loss--that is, patients who are more than six months post-stroke.
"Right now, the 'standard of care' for vision stroke patients is that they don't receive any targeted therapy to restore vision," Saionz says. "They might be offered therapy to help maximize the use of their remaining vision or learn how to navigate the world with their new limited vision, but there are no treatments offered that can give them back any of the vision that they lost."
The new study compared chronic patients--those who were more than six-months post-stroke--with early subacute patients, who started training within the first three months after their stroke.
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The researchers discovered that the subacute patients who underwent such vision training recovered global motion discrimination--the ability to determine the direction of motion in a noisy environment--as well as luminance detection--the ability to detect a spot of light--faster and much more efficiently than the chronic patients.
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"For the first time, we can now conclusively say that just as for sensorimotor stroke, 'time is vision' after an occipital stroke," Huxlin says.
Source-Eurekalert