Clinical Application of Optokinetic Nystagmus: Optokinetic Pattern Test

Abstract

Optokinetic nystagmus was provoked by constant acceleration followed by constant deceleration of an electrically controlled rotating drum. Nystagmus thus induced was recorded on a chart fed at the speed of 0.1 cm sec^-1. A two-channel electronystagmograph was used with time constants of 6 sec and 0.015 sec, in order to approximate the former to eye deviation and the latter to eye speed. Eye speed of the slow phase of induced nystagmus in normals increases and decreases in close approximation to the angular speed of the drum, giving a cone-like appearance as illustrated. The authors denominated the patterns thus obtained “optokinetic pattern” (OKP), and the procedure, “OKP test”. OKP was modified by a weak spontaneous vestibular nystagmus in proportion to its degree. When optokinetic stimulation was applied to spontaneous nystagmus of ocular or central origin, OKP appeared to show characteristic patterns according to causative lesions. An analysis of these patterns, therefore, is expected to contribute to differentiation and identification of spontaneous nystagmus.