VRT is based on the principle of neuroplasticity, in which the brain's self-repair capacity is activated.
Omaha, NE-Patients with neurologic forms of vision loss have shown measurable improvement in their vision after 6 months of rehabilitative therapy. Studies using vision restoration therapy (VRT, Nova-Vision) indicate that patients can gain on average approximately 5° of visual field, according to Richard H. Legge, MD, a neuro-ophthalmologist and pediatric ophthalmologist in private practice in Omaha, NE.
Data from various studies of Nova-Vision VRT have shown that among more than 700 patients who have been treated, more than 65% have achieved improvement in their vision after an initial treatment period of 6 months. Studies also indicate that the treatment effect is stable.
"At first glance, 5° of visual field improvement might not seem like very much, but even a small change in the central visual field can improve a patient's vision," he said.
Patients who have improvement after VRT typically gain ability in reading, mobility, quality of life, and various activities of daily living, according to Navroze S. Mehta, president and chief executive officer of NovaVision. Studies indicate that these improvements persist, and that the condition is very stable 6 to 12 months after completion of therapy.
"What you gain, you keep," Mehta said.
VRT is based on the principle of neuroplasticity, in which the brain's self-repair capacity is activated; partially damaged neurons in the brain compensate for injury and adjust their activity in response to stimulation from the environment. Neuroplasticity may work by axonal sprouting, activation of previously nonfunctioning neurons, or transfer of function from one set of neurons to another, Dr. Legge said. He added that there are other possible mechanisms of action, including the possibility that visual function improves through visual attention, in which the patient is re-trained to use his or her remaining vision more effectively. A third theory is that VRT improves the patient's ambient visual processing.
Patients who are potential candidates for VRT undergo a series of visits and examination of their medical and ophthalmologic records. If VRT seems appropriate, diagnostic tests are performed and the results are used to create a customized vision therapy. The patient receives the VRT medical device, a laptop computer, to take home for daily therapy sessions. It is recommended that patients conduct two 20-minute sessions a day, 6 days a week, for 6 months.
If patients are continuing to show improvement at the end of the 6-month period, therapy can be extended for another 6 months. Studies show that in some patients, additional significant improvement can occur during a second round of therapy, Dr. Legge said. However, if a patient has improvement early in the initial treatment period and then reaches a plateau, therapy will not be extended.
At the start of therapy, the VRT system performs a visual field test that identifies the partially sighted areas, which are transition zones between the normally sighted and blinded areas where there is potential for recovery, Dr. Legge said.
"What the treatment program does is continuously stimulate these various transition zones," he said. "On a monthly basis those transition zones change, and the data are sent back to NovaVision. They update the treatment program to optimize progress, and the patient continues again with the therapy."
While vision or visual function can be enhanced in the transition zones, not all of a patient's visual field defects will disappear.
"But if you can improve the visual function in these transition zones even a small degree, given that they are very close to the center of the patient's vision, then you can improve how well a patient functions in terms of the ability to get around a room, in terms of the ability to read, in terms of the ability to acquire objects while traveling in a motor vehicle," Dr. Legge said.
He became interested in VRT as a means of providing better therapy to patients who have experienced neurologic vision loss.