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

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.