Classification of Optokinetic After-Nystagmus (OKAN) and Its Topical-Diagnostic Significance in Humans.

Optokinetic after-nystagmus (OKAN), which is often neglected today, is based on various pathological eye movements and occurs roughly between spontaneous and provoked nystagmus on the one hand and experimental nystagmus on the other. OKAN is not induced through an intense stimulus like caloric or rotatory nystagmus, however, so that it is of additional clinical importance besides its usefulness in the determination of subtle differences between the two sides. In this report the reaction modes of OKAN have been classified and summarized and its clinical significance is described.1) Barany R : Physiologie und Pathologie des Bongengansapparates beim Menschen. pp 107-142, Franz Deuticke, Leipzig and Vienna, 19072) Brandt T, Dichgans J, Buchele W : Motion habituation : inverted self-motion perception and optokinetic after-nystagmus. Exp. Brain Res 21 : 337-352, 19793) Sakata E, Nagashima C : Diagnostic evaluation of optokinetic after-nystagmus (OKAN). Otolaryngol (Tokyo) 42 : 589-596, 19704) Itoh A, Ohtsu K, Sakata E : Diagnostic contribution of optokinetic after nystagmus (OKAN) Eguilibrium Res 43 : 243-255, 1984