Medical Device Daily Associate
Researchers at the American Academy of Neurology 's (AAN; St. Paul, Minnesota) 58th annual meeting reported positive results from the largest retrospective study conducted to date of stroke and brain trauma patients seeking improvement of vision impairment with NovaVision 's (Boca Raton, Florida) Vision Restoration Therapy (VRT).
VRT is based on the concept of neuroplasticity, the ability of partially damaged neurons in the brain to compensate for injury, in this case to vision, and adjust their activity in response to stimulation from the environment.
The therapy was granted FDA 510(k) approval in April 2003 and is intended for the diagnosis and improvement of visual functions in patients with impaired vision that may result from trauma, stroke, inflammation, surgical removal of brain tumors or brain surgery, and may also be used in patients with amblyopia.
Computer-based, VRT employs visual stimulation to restore large portions of vision lost as a result of brain trauma or damage to the optic nerve. After a stroke or traumatic head injury, a zone of residual vision exists between damaged and undamaged regions within vision-processing areas. Within this zone, there are areas that can be improved using precise patterns of visual stimulation, according to NovaVision. This stimulation of undamaged neurons can increase their functionality.
A paper at the AAN meeting titled, “Restoring Visual Function after Brain Injury: A Large-Sample Retrospective Study Using Vision Restoration Therapy (VRT),“ followed 302 patients with stroke- and brain trauma-related visual field deficits who had completed a six month regimen of daily VRT therapy.
Presenter Bernhard Sabel, PhD, professor and chair of medical psychology at the University of Magdeburg (Magdeburg, Germany), reported that 70.9% patients exhibited moderate or dramatic visual field improvement. The average improvement of visual field was 5 degrees.
Sabel said the findings emphasized the clinical relevance of neuroplasticity of the visual system and confirms that VRT is an effective home-based rehabilitation method for restoring visual function caused by stroke or traumatic brain injury.
“This large-sample trial reinforces the finding of previous small-sample studies, like the 1998 study published in Nature Medicine – VRT is an effective therapy to improve vision deficits caused by stroke and brain trauma,“ Sabel said. “For example, improving the visual field by 5 degrees enables patients to regain the capability to read or watch television, among other hobbies.“
Sabel is a member of the scientific and medical advisory board of NovaVision and he co-developed VRT based on more than 15 years of clinic research.
Sabel's treatment, developed with colleagues Erich Kasten, Stefan Wust and Wolfgang Behrens-Baumann, has been demonstrated to be effective for those patients whose strokes or injuries have left them with a narrowed field of vision. For these individuals, the normal view of the world is replaced by a narrow field of vision that divides itself into three distinct areas.
In areas where cells have escaped harm, vision remains normal. Where massive cell death has occurred in either the optic nerve or vision-processing areas there is simply insufficient sensory information for the brain to construct an image.
Sabel's ability to explore the brain's recuperative powers – and later develop a vision-reclamation technique – was made possible by the personal computer. The PC's first use is to locate survivor cells in the affected area of the brain and determine if there are enough of them to retrain. In this examination, patients focus on a fixation point, which appears as a star on a computer monitor. They are instructed to watch for the appearance of flashing white dots and respond by hitting a letter on the computer's keyboard.
To help keep the subjects' eyes from wandering, researchers also tell them to hit the key when the star changes colors. Analyzing the hit count determines if there are sufficient “islands of residual vision“ that can be expanded with follow-up treatment. According to the company, usually 10% or more of cell survival is sufficient for recovery.
The treatment is similar to the evaluation and can be done at home. As in the test, the patient sits in front of the computer and strikes a key when he sees dots. The company believes this repetitive activity strengthens the connections among the surviving neurons.
The initial phase of therapy typically lasts for six months. In this phase, a patient will perform one hour of daily therapy prescribed in time intervals based upon the individual's needs and abilities. NovaVision evaluates patients' results, and the individual therapy is updated based on progress. Later, the patient returns to a partner clinic to receive an updated program for the next four weeks of therapy, along with a comprehensive summary of an individual's progress.
A second study presented via a poster presentation, by Sabel and Iris Mueller, a colleague from the University of Magdeburg, demonstrated the stability of visual field improvements with VRT.
Titled “Stability of Visual Field Improvements 3.8 Years after Discontinuing Vision Restoration Therapy (VRT),“ the study monitored 24 patients who previously conducted VRT for six or 12 months and demonstrated an improvement in visual field.
The data demonstrated that VRT produced visual field size increases that were stabile over at least 3.8 years. This stability was irrespective of whether patients previously conducted VRT for six or 12 months, suggesting that restored sectors of the visual fields are maintained and used in every day vision.
NovaVision said the need for a rehabilitative therapy like VRT is substantial – about 1.5 million stroke and traumatic brain injury (TBI) patients in the U.S. suffer from major visual field deficits, and that number grows by more than 90,000 new patients each year.
“These studies provide further evidence to support clinical applications of neuroplasticity including VRT. It was previously believed visual field loss in stroke and TBI patients could not be improved, but clinical data on the efficacy of VRT continue to prove the contrary,“ said NovaVision President and CEO Navroze Mehta. “Like speech, physical and occupational therapies, VRT has emerged as a new pillar of therapy that substantially improves the quality of life for these patients.“