Vision Rehab: New Hope for Stroke Patients
HealthyWoman from Bottom Line | October 2011
When you think of all the devastating consequences of stroke, visual impairment may not be one of the first to come to mind... yet about 20% to 25% of stroke victims are left with vision problems. These visual deficits were once thought to be permanent—but now a promising new therapy is helping train the brain to see better again. The research on visual retraining is so exciting that I simply must share it with my readers. And even though the software used for this therapy is not yet commercially available, interested patients may be able to benefit from it by participating in ongoing research studies.
I spoke with neuroscientist Krystel R. Huxlin, PhD, an associate professor of ophthalmology at the Flaum Eye Institute at the University of Rochester School of Medicine and Dentistry, who is the researcher at the forefront of the development of the technique. She explained that stroke patients who suffer damage to a part of the brain called the primary visual cortex typically are blind in one-quarter to one-half of their normal visual field. Reason: The primary visual cortex acts as a gateway for the transfer of information between the eyes and the other brain areas that process visual information. If that gateway is damaged by stroke, patients may have problems with most everyday activities, including reading, driving and even walking.
How Vision Retraining Works
To address the problem, Dr. Huxlin explained, her team first runs tests to map a patient’s blind field and understand his or her exact visual impairments. Then, the visual retraining software is customized to address that patient’s needs.
On a home computer, the patient uses the specialized software to do targeted visual exercises for about an hour at least five days per week. Dr. Huxlin’s patients train for a minimum of three months—and most choose to continue much longer because their blind field continues to shrink and results are so rewarding.
During each training session, the patient fixes her gaze on a small black square in the middle of the screen. Every few seconds, a group of about 100 small dots appears within a circle on the screen that is somewhere in her damaged visual field. The dots appear to move as a group to the left or right, then disappear after half a second. The patient decides which way the dots are moving, indicating her choice with the keyboard. A chime signals whether she has chosen correctly, providing feedback that speeds up learning.
At first, most patients cannot actually see the dots, but nonetheless their brains are able to sense that the dots are moving, Dr. Huxlin said. With practice, a patient’s brain eventually recovers the ability to consciously perceive the dots and discern the direction of their movement in the retrained blind field location. Then, the researchers move the dots to another spot in her blind field so the brain can start relearning how to see the new area.
Secret to success: The therapy exploits a phenomenon called blindsight, in which a stroke patient’s eyes are able to take in visual information but the damaged brain cannot make sense of it to create conscious vision. "The training drives whatever spared visual circuitry the person still has, making it work harder, so eventually that visual information is brought into consciousness," said Dr. Huxlin. The 17 patients she has studied so far who trained as prescribed all had significantly improved vision. The improvement seems to be permanent—and some patients have even been able to regain a driver’s license.
Who Can Benefit
Visual retraining potentially can benefit patients whose strokes were recent and those whose strokes occurred several years ago, Dr. Huxlin told me, provided they are not totally blind. Patients also must be able to complete basic tasks, such as using a computer, fixating points on the screen precisely, pressing keys and following instructions.
Dr. Huxlin’s visual retraining software has been licensed by the company EnVision LLC and submitted for FDA approval. It is hoped that the product will be commercially available shortly after FDA approval is obtained. In the meantime, stroke survivors interested in participating in Dr. Huxlin’s ongoing research can e-mail her at firstname.lastname@example.org to see if they meet the criteria for study enrollment and, if so, they will be put on a waiting list.
Also helpful: Dr. Huxlin said that, in addition to visual retraining, stroke sufferers can help compensate for vision loss by staying as physically active as possible—for instance, by playing sports such as golf or tennis or by regularly taking walks around the neighborhood or a park. "Those kinds of activities force you to make up for visual deficits by moving your head and eyes more. This pushes your visual system to be more actively engaged—to search for and find the information you need to extract from your environment in order to function," she explained. For patients unable to engage in sports or walk outside, playing action video games would be a reasonable alternative, she added. Bottom line: For stroke survivors, the future has never looked brighter.
Source: Krystel R. Huxlin, PhD, is a neuroscientist and an associate professor of ophthalmology at the Flaum Eye Institute at the University of Rochester School of Medicine and Dentistry in New York. Her research on visual retraining for stroke patients has been published in The Journal of Neuroscience.