Effects of retinal image stabilization in acquired nystagmus due to neurologic disease

Abstract

We studied the effects of variable amounts of artificial retinal image stabilization (RIS) upon oscillopsia and visual acuity in eight patients with acquired nystagmus due to neurologic disease. We measured horizontal and vertical eye movements with the magnetic search coil technique and used these electronic signals to control the position of a visual stimulus on a screen in front of the patient. We also used an optical device to stabilize images of the real world upon the retina. During electronic stabilization, RIS was progressively increased until oscillopsia was abolished; this was achieved in all eight patients and corresponded to retinal image drift of 5 degrees/sec or less. In five patients with downbeat nystagmus, further increases in RIS caused the oscillopsia to reappear, but in the opposite direction. Electronic stabilization also improved visual acuity in four of five patients; the limitation of improvement could be related to coexistent visual system defects. Using electronic feedback, we could measure the range of RIS that any individual required to abolish oscillopsia; from this measurement, the components of the optical device that were best suited to provide a stable field of vision could be calculated.

Therapy for Nystagmus

“…Because the contact lens moves with the eye, it does not negate the effect of retinal image stabilization due to the spectacle lens. With such high-positive spectacle lens and high-negative contact lens combinations, it is possible to negate about 90% of the visual effects of eye movements (93). However, this approach impairs all eye movements, including the VOR and vergence, so that it is only useful when the patient is stationary and viewing monocularly.…”

Drug therapy for acquired pendular nystagmus in multiple sclerosis

“…Patients regularly experience an illusory motion of the environment which interferes with their ability to read or watch television and even to visually stabilize their posture [21,22,37]. They can present with a nystagmus that is horizontal, vertical, or "mixed", i.e., with a circular, elliptical, or diagonal trajectory.…”

The mechanism of oscillopsia and its suppression

“…In our first formal study of OSOP suppression in INS, we measured the effects of retinal image stabilization (RIS) on four subjects with INS 20 . None of these subjects experienced OSOP under normal conditions.…”

“…There is a large body of research on the topic of OSOP, and this paper is not meant to be a review of that literature. [18][19][20][21][22][23][24][25][26][27][28][29][30][31] Rather, it is aimed at uncovering and modeling the mechanism of OSOP suppression and is based on four of the author's observations and six studies of OSOP made by the author and his colleagues over a period of approximately 57 years. The bibliographies of these studies contain many relevant studies of OSOP.…”