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Logo for the Journal of Rehab R&D
Volume 41 Number 3a, May/June 2004
Pages 325 — 336

Abstract - Image-shifting optics for a nystagmus treatment device
Ryan M. Smith, BSEE; Brian S. Oommen, MS; John S. Stahl, MD, PhD
Departments of Neurology, Louis Stokes Cleveland Veterans Affairs Medical Center and Case Western Reserve
University, Cleveland, OH
Abstract — Acquired pendular nystagmus (APN) complicates multiple sclerosis and other neurological disorders, causes visual impairment, and is often refractory to available treatments. Vision could be improved by an optical aid that shifts the seen world in lockstep with the APN. An essential component of such a device is the image-shifting mechanism, which must be light, accurate, suitable for battery operation, and capable of image shifting at the frequencies and amplitudes seen in APN. We determined that a three-lens image-shifting mechanism used in commercial image-stabilizing lenses has the potential to satisfy all these requirements. In combination with software designed to track nystagmus, the optical mechanism proved capable of improving visual acuity in 12 normal subjects experiencing simulated two-dimensional nystagmus. Acuity was restored to within an average of 0.12 logMAR (range 0.0-0.22) of the subjects' values without the simulated nystagmus. These results support the feasibility of an assistive device for patients with APN.

Key words: adaptive filter; adaptive optics; demyelination; image stabilization; multiple sclerosis; nystagmus, pathological; oscillopsia; visual acuity.

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