NEW ORLEANS, Feb. 3 – Patients who lose vision after stroke can regain some of it through therapy that strengthens nerve cell activity, researchers reported at the American Stroke Association's International Stroke Conference 2005.
"This is the first technique stroke patients can use to improve their vision," said Bernhard Sabel, Ph.D., professor of medical physiology at Otto-von-Guericke University in Magdeburg, Germany. "Patients with visual field defects can now have reasonable hope that the blindness is changeable. This study found that the effect of therapy lasts well after therapy stops and indicates that extended training tends to further improve results."
Vision restoration therapy (VRT) involves identifying and stimulating regions in the visual field that are only partly damaged by stroke or trauma. The training can be done at home in front of a computer-based device, usually in 30-minute sessions, twice a day.
During the training, hundreds of visual stimulations are presented on the monitor to the areas of residual vision. Through repetitive use of damaged areas, a process known as neuroplasticity is induced. During neuroplasticity, the nerve activity related to vision is strengthened to help restore some of a person's visual functions.
Sabel and his colleagues presented findings from six and 12 months of VRT. Fifteen patients underwent six months of VRT and nine patients had 12 months of VRT. Visual field assessments were performed before and after VRT and then repeated an average of 46 months after completing VRT. After six months of VRT, sample stimulus detection increased significantly from about 54 percent to 63 percent. The number of undetected stimuli decreased significantly in both eyes.
Continuing VRT for 12 months improved the results achieved at six months. However, this change was only a statistical trend toward improvement and was not a significant change. Sabel and his colleagues had observed in a separate study that the difference became statistically significant when a larger group of patients was studied.
The follow-up examination after a therapy-free interval of more than three years showed that the benefits of VRT remained stable, and vision loss did not occur in most instances. Patients appear to benefit by continuing the training rather than stopping after a certain period of time.
"The improvement remains stable in most patients," he said. "Continued therapy, however, is helpful to further improve the outcome." Patients with vision loss after stroke benefit regardless of the severity of the stroke or how much of their vision is affected, Sabel said. As long as some vision remains, VRT is effective in most patients. The larger the areas of residual vision, the better the outcome with VRT, he said.
"We had some patients train for many years and continue to improve," he said. "In rare cases, the entire [area of vision loss] disappeared."
Even a patients' age didn't influence the likelihood of improvement.
"The age of the patient does not matter much," Sabel said. "It also does not matter how old the lesion is at the start of the training, even when it is decades old patients can still benefit."
However, he said, VRT has varying results. About one-third of patients he studied had little or no effect from VRT, one-third had moderate but noticeable improvement, and one-third had strong or dramatic improvement.
Patient compliance with the technique has been very good. Patients tend to continue with the therapy, even undergoing training for an extended period of time. The same training technique can be applied to vision loss due to trauma (including optic nerve damage) and to tumor surgery that affects visual fields.
Co-authors are Carolin Gall, M.A.; Iris Mueller, M.A.; and Christian Kaufmann, Ph.D.
The study was funded by the University of Magdeburg and the DFG (Germany).
VRT has been approved for marketing by the U.S. Food and Drug Administration and is distributed by NovaVision, Inc.
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