congenital nystagmus

congenital nystagmus

n.

1. A congenitally predetermined nystagmus caused by lesions sustained in utero or at the time of birth.

2. An inherited, nonprogressive, usually sex-linked nystagmus without associated neurologic lesions.

3. The nystagmus associated with albinism, achromatopsia, and hypoplasia of the macula.

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nystagmus [nis-tag´mus]

involuntary, rapid, rhythmic movement (horizontal, vertical, rotatory, or mixed, i.e., of two types) of the eyeball. adj., adj nystag´mic.

amaurotic nystagmus nystagmus in the blind or in those with defects of central vision.

amblyopic nystagmus nystagmus due to any lesion interfering with central vision.

aural nystagmus labyrinthine nystagmus.

caloric nystagmus rotatory nystagmus in response to caloric stimuli in the ear, seen during the caloric test.

Cheyne's nystagmus a peculiar rhythmical eye movement resembling Cheyne-Stokes respiration in rhythm.

congenital nystagmus (congenital hereditary nystagmus) nystagmus usually present at birth, usually horizontal and pendular, but occasionally jerky and pendular; the nystagmus may be caused by or associated with optic atrophy, coloboma, albinism, bilateral macular lesions, congenital cataract, severe astigmatism, and glaucoma.

dissociated nystagmus that in which the movements in the two eyes are dissimilar.

end-position nystagmus that occurring only at extremes of gaze.

fixation nystagmus that occurring only on gazing fixedly at an object.

gaze nystagmus nystagmus made apparent by looking to the right or to the left.

labyrinthine nystagmus vestibular nystagmus due to labyrinthine disturbance.

latent nystagmus that occurring only when one eye is covered.

lateral nystagmus involuntary horizontal movement of the eyes.

optokinetic nystagmus nystagmus induced by looking at objects moving across the visual field.

pendular nystagmus nystagmus in which the oscillations of the eyes have an equal rate, amplitude, direction, and type of movement.

positional nystagmus that which occurs, or is altered in form or intensity, on assumption of certain positions of the head.

retraction nystagmus (nystagmus retracto´rius) a spasmodic backward movement of the eyeball occurring on attempts to move the eye; a sign of midbrain disease.

rotatory nystagmus involuntary rotation of the eyes about the visual axis.

secondary nystagmus nystagmus occurring after the abrupt cessation of rotation of the head, caused by the labyrinthine fluid continuing to move.

spontaneous nystagmus that occurring without specific stimulation of the vestibular system.

vertical nystagmus involuntary up-and-down movement of the eyes.

vestibular nystagmus nystagmus due to disturbance of the labyrinth or of the vestibular nuclei; the movements are usually jerky.

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nystagmus

a periodic, rhythmic, involuntary movement of both eyeballs in unison. There is a slow component in one direction and a quick return. The movement may be vertical, horizontal or rotary. Common causes are lesions of the cerebellum or the vestibular apparatus, or increased intracranial pressure.

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aural nystagmus

labyrinthine nystagmus.

cerebellar nystagmus

one characterized by tremor, without fast and slow components.

Cheyne's nystagmus

a peculiar rhythmical eye movement resembling Cheyne-Stokes respiration in rhythm.

congenital nystagmus

may be a primary functional defect or secondary to lesions in the visual pathways, sometimes associated with albinism. Reported in cattle, cats (particularly Siamese), and dogs.

dissociated nystagmus

that in which the movements in the two eyes are dissimilar.

gaze nystagmus

nystagmus made apparent by looking to the right or to the left.

horizontal nystagmus

that in which the eyes move from side to side with the fast component opposite to the side of the lesion; seen with central or unilateral peripheral vestibular disease.

jerk nystagmus

vestibular nystagmus (see below).

labyrinthine nystagmus

vestibular nystagmus due to labyrinthine disturbance.

latent nystagmus

that occurring only when one eye is covered.

lateral nystagmus

involuntary horizontal movement of the eyes.

ocular nystagmus

wandering movement of the eyes as though searching for something. Associated with congenital blindness.

optokinetic nystagmus

nystagmus induced by looking at objects moving across the field of vision.

oscillatory nystagmus

pendular nystagmus.

pendular nystagmus

that which consists of to-and-fro movements of equal velocity.

positional nystagmus

that which occurs, or is altered in form or intensity, on assumption of certain positions of the head.

postrotatory nystagmus

a normal finding after the animal has been rotated, with the fast phase away from the direction of rotation.

resting nystagmus

that occurring while the head is stationary.

retraction nystagmus, nystagmus retractorius

a spasmodic backward movement of the eyeball occurring on attempts to move the eye; a sign of midbrain disease.

rotatory nystagmus

involuntary rotation of the eyes about the visual axis.

spontaneous nystagmus

that occurring without specific stimulation of the vestibular system.

vertical nystagmus

involuntary up-and-down movement of the eyes.

vestibular nystagmus

nystagmus due to disturbance of the labyrinth or of the vestibular nuclei; the movements are usually jerky.

undulatory nystagmus

an inherited disorder of Finnish Ayrshire cattle; there is a synchronous, tremor-like movement of the eyes but affected aninals are otherwise healthy.