Binocular ocular motility: breaking with the past: how understanding dynamic ocular motor control and central nervous system plasticity promote novel discovery and therapy of nystagmus.

Introduction: The lure of studying the ocular motor system stems from its anatomic and physiological accessibility, ease of measurement and analysis of function, as well as the promise of providing a direct window into the brain. There is an increasing body of knowledge on how the brain responds to peripheral eye muscle manipulation (surgery, medications, denervation, genetic therapy). Investigations in both animals and humans have established that plasticity within the brain occurs after peripheral neuromuscular (medical or surgical) disruption and repair.

Purpose: This paper will review and summarize neurophysiological concepts resulting from recent investigations of the ocular motor system and treatment of involuntary oscillations such as nystagmus.

Methods: Review of both a multidisciplinary literature and the authors 25 years experience evaluating, treating and investigating the ocular motor system.

Conclusions: The ocular motor system in man is a continuously controlled, malleable brain-eye system, which is genetically programmed, environmentally modified and contains powerful reparative processes. It begins during development, extends throughout life and is subject to external manipulation in both health and disease. These ideas challenge the historically significant axiom, i.e., that there is eventual (and a final maturing to an end state) "hard-wiring" of much of both the ocular motor and afferent visual systems. Rather, they now are shown to maintain some degree of plasticity throughout life.