| nystagmus, physiologic | Involuntary rhythmical movements of the eyes in the normal person. These can be naturally occurring as in end-position (end-point, end-stage, or deviational) nystagmus or induced by the optokinetic drum (nystagmus, optokinetic), caloric test, or a rotating chair. (12 Dec 1998) |
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| nystagmus test | A test for vestibular function, made by irrigating the external auditory meatus with either hot or cold water; this normally causes stimulation of the vestibular apparatus, resulting in nystagmus and past-pointing; in vestibular disease, the response may be reduced or absent. Synonym: caloric test, nystagmus test. (05 Mar 2000) |
| deviational nystagmus | A jerky, physiologic nystagmus occurring in a normal individual when attempts are made to fixate a point at the limits of the field of fixation. Synonym: deviational nystagmus. (05 Mar 2000) |
| dissociated nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
| downbeat nystagmus | A vertical nystagmus with a rapid component downward, occurring in lesions of the lower part of the brainstem or cerebellum. (05 Mar 2000) |
| dysjunctive nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
| incongruent nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
| irregular nystagmus | A nystagmus in which the movements of the two eyes are dissimilar in direction, amplitude, and periodicity. Synonym: dysjunctive nystagmus, incongruent nystagmus, irregular nystagmus. (05 Mar 2000) |
| ocular nystagmus | The pendular or, rarely, jerky nystagmus seen in severely reduced vision. Synonym: amaurotic nystagmus. (05 Mar 2000) |
| opticokinetic nystagmus | Nystagmus induced by looking at moving visual stimuli. Synonym: opticokinetic nystagmus, railroad nystagmus. (05 Mar 2000) |
| optokinetic nystagmus | Nystagmus induced by looking at moving visual stimuli. Synonym: opticokinetic nystagmus, railroad nystagmus. (05 Mar 2000) |
| end-point nystagmus | A jerky, physiologic nystagmus occurring in a normal individual when attempts are made to fixate a point at the limits of the field of fixation. Synonym: deviational nystagmus. (05 Mar 2000) |
| jerky nystagmus | Nystagmus in which there is a slow drift of the eyes in one direction, followed by a rapid recovery movement, always described in the direction of the recovery movement; it usually arises from labyrinthine or neurologic lesions or stimuli. (05 Mar 2000) |
| upbeat nystagmus | A vertical jerky nystagmus with a rapid component upward, occurring with brainstem lesions. (05 Mar 2000) |
| fixation nystagmus | Nystagmus aggravated or induced by ocular fixation, arising as optokinetic nystagmus, or resulting from midbrain lesions. (05 Mar 2000) |