A new study confirms previous data that patients with visual field defects from stroke or traumatic brain injury can rehabilitate their brains ability to see. The method: non-invasive Vision Restoration Therapy (VRT), an at-home computer-based vision therapy method patented by NovaVision, of Boca Raton, Fla. VRT was cleared by the FDA in April 2003.
The study evaluated 118 patients who had post-chiasmatic lesions and homonymous field defects at least three months post-trauma. Patients underwent six modules of therapy (24 weeks). Each course consisted of visual exercises in which patients focused on a screen and responded to a stimulus, which appeared at the edges of their visual field defects.
Results were measured by suprathreshold campimetry of the central macula before, during and after therapy. Outcomes were measured mainly by the proportion of stimuli responded to and the border shift of each patients visual field.
The study found that a six-module course of VRT improved the stimulus detection of 70% of patients by at least 3%. Researchers also noted that better rates of stimulus detection after the third module of therapy reg- ularly indicated better rates of visual field expansion post-VRT. Also, there were no indications that age, type of visual field defect, or amount of time post-trauma impacted the outcome of the therapy. These results were announced in early February at the International Stroke Conference held in
Prior studies of VRT have found conflicting or inconclusive findings, though. At least one study suggests that the improvement in visual fields in patients who have used VRT is actually the result of miniscule eye movements compensating for the visual field deficit.1,2 Another study demonstrates positive results, but notes trouble quantifying them; however, this study also suggests that the recorded decrease in reaction time could validate the theory that neuroplasticity plays a role in post-traumatic vision restoration.3
VRT is rooted in the principle of neuroplasticity: The brain is able to adapt and compensate for injury due to trauma. The longstanding view of the brain was that it was hard-coded and immutable, and that any brain injury suffered after childhood would remain permanent, says researcher Jose Romano, M.D., a neurologist at the
1. Pelak VS, Dubin M, Whitney E. Homonymous hemianopia: A critical analysis of optical devices, compensatory training, and NovaVision. Curr Treat Options Neurol 2007 Jan;9(1) :41-7.
2. Kasten E, Bunzenthal U, Sabel BA. Visual field recovery after vision restoration therapy (VRT) is independent of eye movements: an eye tracker study. Behav Brain Res 2006 Nov 25;175(1):18-26. [Epub 2006 Sep 12.]
3. Sabel BA, Kenkel S, Kasten E. Vision restoration therapy (VRT) efficacy as assessed by comparative perimetric analysis and subjective questionnaires. Restor Neurol Neurosci2004;22(6):399-420.