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| Better by looking |
| Nicole Ostrow / Apr 05, 2009, 00:29 IST |
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Restoring sight after a stroke is possible with vision exercises.
Patients who are partially blinded by a stroke can recover some vision by retraining their brains with vigorous eye exercises, a study showed. The patients who engaged in the exercises on a computer every day for nine to 18 months were able to improve their vision significantly, research reported in the latest Journal of Neuroscience found.
The findings show that doctors may finally have a way to help stroke victims regain some lost sight in addition to improving speech and movement, said the lead study author, Krystel Huxlin. More research is needed to confirm the findings, she said.
“This should become just as routine as physical therapy,” said Huxlin, associate professor of ophthalmology at the University of Rochester Eye Institute, in Rochester, New York, in a telephone interview today. “My hope is down the road that this will be freely available.”
She added, “There’s a big need.”
Strokes each year afflict about 795,000 people in the US, according to the US Centers for Disease Control and Prevention. The condition kills more than 143,000 people, making it the third-largest cause of death, behind heart disease and cancer, and the leading cause of serious, long-term disability in the US, according to the American Heart Association.
PROCESSING SIGHT
Researchers studied seven people who had suffered a stroke that damaged the part of the brain known as the primary visual cortex. Five completed the study, while two were used as controls and didn’t receive the visual exercises.
The primary visual cortex is the gateway to the rest of the brain for most of the visual information that comes through the eyes, Huxlin said. That area passes visual information along to dozens of other parts of the brain, which then makes sense of the information, allowing people to see.
Those with damage to the primary visual cortex often can’t drive, read or do ordinary chores like shopping. The damage can cause blindness in one-quarter to half of the normal field of view, making any objects left or right of centre appear gray or dark.
The goal of the study was to see if the area of the brain that focuses on motion perception could be stimulated enough that it would take on some of the roles previously handled by the damaged primary visual cortex.
SEEING DOTS
Participants in the study stared at a small black square in the middle of a computer screen while every few seconds a group of about 100 small dots appeared on the screen somewhere in the area relevant to where the person’s vision was damaged.
The patients’ brains initially couldn’t process that the dots were present, although their eyes were taking in the information. The patients were asked to choose whether the dots moved left or right. When they were correct, a chime would toll, providing feedback to the brain and speeding up learning, the researchers said.
After daily exercises of 15 to 30 minutes once or twice a day, the patients’ brains began to process the information, allowing them to become aware of the dots, the authors said. The researchers then moved the dots further into the blind areas, to help improve sight even more.
The process is gruelling and can take a long time, Huxlin said. It can take up to two months to retrain the brain to see one part of the blind area, and there can be hundreds of areas, depending on the amount of vision loss, she said.
SPEEDING RECOVERY
Huxlin is trying to come up with ways to speed the recovery time, including possibly using medicines in conjunction with the visual exercises. She is also looking to see if the area of the brain that processes shapes and forms can also be retrained to see.
Strokes occur when the blood flow to the brain stops. They can be caused by a blood clot that blocks a blood vessel in the brain or by a blood vessel that breaks and bleeds in the brain, according to the National Institutes of Health.
The study was funded by Research to Prevent Blindness, the Pfeiffer Foundation, the Schmitt Foundation and the National Eye Institute.
Huxlin said doctors shouldn’t send patients who are blinded by a stroke home saying there’s nothing that can be done.
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