Noun | 1. | nystagmus - involuntary movements of the eyeballs; its presence or absence is used to diagnose a variety of neurological and visual disorders eye movement - the movement of the eyes physiological nystagmus - small involuntary tremors of the eyeballs; when it is eliminated by stabilizing the image on the retina, visual perception fades rapidly from fatigue of the retinal receptors rotational nystagmus - nystagmus caused by the body rotating rapidly; large slow movements of the eyeballs are in the direction of rotation post-rotational nystagmus - nystagmus caused by suddenly stopping the rapid rotation of the body; large slow movements of the eyeballs are in the direction opposite to the direction of rotation |