Homonymous Hemianopia: A Critical Analysis of Optical Devices, Compensatory Training, and NovaVision.
Homonymous hemianopia (HH) results from damage to visual pathways posterior to the optic chiasm. Due to the significant functional impairment that can result, rehabilitative techniques and devices intended to improve visual function after HH have been explored and are reviewed here. Two basic treatment strategies include use of optical devices and compensatory training. A third strategy, purported to be based on the principles of neuronal plasticity of the visual cortex, is aimed at visual field recovery by computerized training. This strategy is trademarked as visual restoration therapy (VRT) by NovaVision (Boca Raton, FL), which began marketing its commercialized therapy program in 2003 for the treatment of visual loss related to stroke and traumatic brain injury. In regard to compensatory training and optical devices, a standardized methodology is lacking, and very few controlled studies exist in regard to efficacy. Outcome data regarding effectiveness of VRT are conflicting, as are the opinions of investigators who have studied and reviewed VRT. There is some evidence that expansion of visual fields by VRT may be the result of very small eye movements. Functional outcomes for each strategy reveal subjective, but limited evidence or no objective evidence of functional improvement; therefore, it is difficult to recommend a specific treatment based on evidence for most patients. The decision to treat and the type of treatment to pursue for patients with HH should be individualized and guided by the type of injury, associated deficits, available resources, and the level of functional impairment manifested by the HH. Consultation with a low-vision specialist (preferably a specialist endorsed by an ophthalmologist or neuro-ophthalmologist) for treatment guidance is recommended.
Pelak
Victoria S
VS
Victoria S. Pelak, MD University of Colorado Health Sciences Center, PO Box 6510, Mailstop F727, Aurora, CO 80045, USA. victoria.pelak@uchsc.edu.
Dubin
Mark
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Whitney
Edward
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