An overview of ocular motor neurophysiology.

A review of current concepts in ocular motor neurophysiology is presented. Four separate subsystems of eye movements are recognized: saccadic, smooth pursuit, vergence, and vestibular. Each subsystem is characterized by different physiologic characteristics and different anatomic substrates which may be selectively affected in different pathologic states. A further eye movement response, optokinetic nystagmus, is complex and may be considered a separate system. To regard the horizontal optokinetic response as merely a combination of pursuit and saccades is an oversimplification but one which may be useful in clinical localization.