nystagmus - involuntary movements of the eyeballs; the presence or absence of nystagmus is used to diagnose a variety of neurological and visual disordersmovement, motility, motion, move - a change of position that does not entail a change of location; "the reflex motion of his eyebrows revealed his surprise"; "movement is a sign of life"; "an impatient move of his hand"; "gastrointestinal motility" physiological nystagmus - small involuntary tremors of the eyeballs; when physiological nystagmus is eliminated by stabilizing the image on the retina the 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 |