Nystagmus and Superior Oblique Myokymia

Abstract

Nystagmus is an involuntary, rhythmic ocular movement that is initiated by a slow drift and comes in two varieties (Fig. 16.1): (1) jerk nystagmus (alternating slow and fast phases) and (2) pendular nystagmus (back-to-back slow phases). Both jerk and pendular nystagmus can have horizontal, vertical, or torsional components in isolation or combination. Some nystagmus manifests very early in life (infantile), while acquired nystagmus can be associated with a variety of pathologic conditions. Acquired nystagmus becomes symptomatic when the pathologic slow phase moves the eyes away from fixation, often causing oscillopsia, or an illusory movement of a stationary object. Therapies proposed for nystagmus include pharmacologic, chemodenervation (e.g., botulinum toxin), surgical, and optical among others. The goal of treatment is to improve vision by stabilizing retinal images. While large-scale randomized controlled trials are generally lacking for the treatment of nystagmus, we will discuss those therapies for which at least some evidence exists.