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The ocular motor system directs the eyes to targets of interest, maintains fixation, pursues moving targets, and stabilizes the eyes in the face of head, body, or background motion. It provides the signals for the perception of a stable world despite retinal image motion. Ocular motor disorders may take the form of nystagmus, saccadic intrusions, saccadic oscillations, or dysmetria. Eye-movement data and analysis allow differential diagnosis of these disorders, and suggestions for, and evaluation of, therapies.

We review current concepts of nystagmus and saccadic oscillations, applying a pathophysiological approach. We begin by discussing how nystagmus may arise when the mechanisms that normally hold gaze steady are impaired. We then describe the clinical and laboratory evaluation of patients with ocular oscillations. Next, we systematically review the features of nystagmus arising from peripheral and central vestibular disorders, nystagmus due to an abnormal gaze-holding mechanism (neural integrator), and nystagmus occurring when vision is compromised. We then discuss forms of nystagmus for which the pathogenesis is not well understood, including acquired pendular nystagmus and congenital forms of nystagmus. We then summarize the spectrum of saccadic disorders that disrupt steady gaze, from intrusions to flutter and opsoclonus. Finally, we review current treatment options for nystagmus and saccadic oscillations, including drugs, surgery, and optical methods. Examples of each type of nystagmus are provided in the form of figures.

Abnormal saccadic intrusions for psychiatric patients during smooth pursuit tasks have been frequently reported in the literature. In this study, 26 schizophrenic, 23 affective, and 8 miscellaneous psychiatric inpatients were compared to 60 controls for smooth pursuit and convergence tracking abilities. Saccadic intrusions occurred far more frequently for psychiatric patients than for controls in both tracking tasks. The findings are consistent with a model proposed by Flach and Kaplan (1983) that psychiatric patients have a spatial management disorder which adapts poorly to motion and interferes with the accurate appraisal of distances and locations.

Abnormal patterns of head/eye coordination that occurred in patients with chronic cerebral lesions comprised increased saccade latencies and hypometria contralateral to the lesion. Frequent saccadic intrusions, often with a distinct asymmetry, and an excess of predictive saccades were seen. Head movements were consistent with the saccadic abnormalities and also changes in the waveform and timing of head movements were noted.