Nystagmus, << nihs TAG muhs, >> is an involuntary, rhythmical movement of the eyes. The eyes may move from side to side, up and down, in a circle, or in a combination of these movements. The motions may be rapid or slow, and jerky or smooth. Nystagmus occurs normally, as when a person watches scenery from a moving train. This condition may also be produced by diseases of the eye, the ear, or the brain. Some people are born with nystagmus.
A type of nystagmus known as miner’s nystagmus is caused by darkness and occurs among miners. Positional nystagmus occurs only when the patient’s head is placed in an abnormal position or level. Spontaneous ocular nystagmus occurs as a result of complete blindness or from defective central vision. Vertical nystagmus is an up-and-down movement of the eyes. Latent nystagmus occurs when one eye is covered.
