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Describe nystagmus with its types and management.

Ophthalmology · 3rd Professional

Definition and Classification

Nystagmus is an involuntary, rhythmic, to-and-fro oscillation of the eyes.
It is described as jerk (a slow drift with a corrective fast phase, and named by the direction of the fast phase) or pendulum (pendular), in which both phases are of equal velocity.
The first question IS always whether there IS oscillopsia — the sensation that the world is moving. Its presence or absence separates the two great groups:

Type	Features
Infantile nystagmus syndrome	Onset in the first 6 months. Characteristically horizontal and uniplanar in all directions of gaze (even on upgaze), with a null zone in which it is least. It dampens ON convergence, is absent IN sleep, and there is NO oscillopsia
Sensory deprivation nystagmus	From bilateral visual loss before 3 months: congenital cataract, albinism, aniridia, optic nerve hypoplasia, achromatopsia and LEBER congenital amaurosis. pendular, and the search is for the underlying cause
Latent nystagmus	Present only when one eye is occluded, with the fast phase toward the uncovered eye. Associated with infantile esotropia and dissociated vertical deviation. Important practical point: occluding one eye to test acuity induces it and gives a falsely low reading, so a fogging lens or a high plus lens should be used instead
Spasmus nutans	A triad of fine, rapid, asymmetrical nystagmus, head nodding and torticollis, beginning at 4 to 12 months and resolving by 3 years. It is benign — but an identical picture is produced by a chiasmal or hypothalamic glioma, so MRI IS mandatory before the diagnosis is accepted
Gaze-evoked nystagmus	On eccentric gaze, from failure of the neural integrator. Causes: drugs (anticonvulsants, sedatives, alcohol) and cerebellar disease
Downbeat nystagmus	Fast phase downward, worse on lateral and downgaze. Indicates a lesion at the craniocervical junction — classically ARNOLD-CHIARI malformation — and also occurs with lithium, anticonvulsants and Wernicke encephalopathy. MRI of the craniocervical junction is mandatory
Upbeat nystagmus	Lesions of the medulla or the anterior vermis; and Wernicke encephalopathy
See-saw nystagmus	One eye rises and intorts while the other falls and extorts. Indicates a parasellar lesion, classically a large pituitary tumour with bitemporal hemianopia
Periodic alternating nystagmus	Horizontal jerk nystagmus that reverses direction every couple of minutes; craniocervical junction disease; responds to baclofen
Convergence-retraction nystagmus	On attempted upgaze, the eyes converge and retract into the orbit; part of parinaud (dorsal midbrain) syndrome, from a pineal tumour or hydrocephalus

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