nystagmus

[ni-stag-muhs]
noun
a congenital or acquired persistent, rapid, involuntary, and oscillatory movement of the eyeball, usually from side to side.

Origin:
1815–25; < Neo-Latin < Greek nystagmós nodding, derivative of nystázein to nod

nystagmic, adjective
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World English Dictionary
nystagmus (nɪˈstæɡməs)
 
n
involuntary movement of the eye comprising a smooth drift followed by a flick back, occurring in several situations, for example after the body has been rotated or in disorders of the cerebellum
 
[C19: New Latin, from Greek nustagmos]

Collins English Dictionary - Complete & Unabridged 10th Edition
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American Heritage
Medical Dictionary

nystagmus nys·tag·mus (nĭ-stāg'məs)
n.
A rapid, involuntary oscillatory motion of the eyeball.


nys·tag'mic (-mĭk) or nys·tag'moid' (-moid') adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Encyclopedia Britannica
Encyclopedia

nystagmus

involuntary back and forth, up and down, or circular movements of the eyes that are often described by observers as "jumping" or "dancing" eye movements. One type of nystagmus, called pendular nystagmus, is characterized by even, smooth eye movements, whereas in the type referred to as jerk nystagmus the movements are sharper and quicker in one direction than in the other. Jerk nystagmus can occur normally, such as when one is dizzy (e.g., from spinning around in circles) or is watching objects pass by quickly from the window of a moving vehicle. Pathologic nystagmus may be present at or shortly after birth because of retinal or optic nerve abnormalities, cataracts, albinism, or a host of other conditions (sensory nystagmus). Alternatively, people can be born with nystagmus and no associated abnormalities of the eye (congenital motor nystagmus). Often there is a gaze or a head position that the affected individual adopts in which the nystagmus is least severe and visual acuity is optimized (called the null point)

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
When a sudden abnormality in the balance of the signals occurs, the result is a pattern of eye movements referred to as nystagmus.
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