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the pendular or, rarely, jerk nystagmus seen in severely reduced vision.
Synonym(s): amaurotic 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.
one characterized by tremor, without fast and slow components.
a peculiar rhythmical eye movement resembling Cheyne-Stokes respiration in rhythm.
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.
that in which the movements in the two eyes are dissimilar.
nystagmus made apparent by looking to the right or to the left.
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.
vestibular nystagmus (see below).
vestibular nystagmus due to labyrinthine disturbance.
that occurring only when one eye is covered.
involuntary horizontal movement of the eyes.
wandering movement of the eyes as though searching for something. Associated with congenital blindness.
nystagmus induced by looking at objects moving across the field of vision.
that which consists of to-and-fro movements of equal velocity.
that which occurs, or is altered in form or intensity, on assumption of certain positions of the head.
a normal finding after the animal has been rotated, with the fast phase away from the direction of rotation.
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.
involuntary rotation of the eyes about the visual axis.
that occurring without specific stimulation of the vestibular system.
involuntary up-and-down movement of the eyes.
nystagmus due to disturbance of the labyrinth or of the vestibular nuclei; the movements are usually jerky.
an inherited disorder of Finnish Ayrshire cattle; there is a synchronous, tremor-like movement of the eyes but affected aninals are otherwise healthy.