CSP: involuntary, rapid, rhythmic movement of the eyeball.,MSH: Involuntary movements of the eye that are divided into two types, jerk and pendular. Jerk nystagmus has a slow phase in one direction followed by a corrective fast phase in the opposite direction, and is usually caused by central or peripheral vestibular dysfunction. Pendular nystagmus features oscillations that are of equal velocity in both directions and this condition is often associated with visual loss early in life. (Adams et al., Principles of Neurology, 6th ed, p272),NCI: A disorder characterized by involuntary movements of the eyeballs.,CHV: involuntary, rapid, rhythmic movement of the eyeball,NCI: Involuntary movements of the eyeballs. The presence or absence of nystagmus is often used in the diagnosis of a variety of neurological and visual disorders.