nystagmus

Nystagmus is a condition characterized by involuntary, rhythmic oscillations of the eyes. The movements can occur in one or both eyes, and a slow drift of the eye is followed by a quick corrective saccade. Patients may experience oscillopsia or blurred vision, and nystagmus can be present from infancy or develop later in life.

Nystagmus is described by direction (horizontal, vertical, rotary), waveform (pendular or jerk), and onset (congenital/infantile or acquired). Horizontal jerk nystagmus is the most common; vertical nystagmus may be upbeating or downbeat; pendular nystagmus features smooth, equal-speed eye movements.

Causes include congenital infantile nystagmus often associated with albinism or optic nerve hypoplasia. Acquired nystagmus can arise from brainstem or cerebellar disease, multiple sclerosis, stroke, vestibular disorders, or drug/toxin effects (ethanol, anticonvulsants); refractive errors and visual impairment can contribute.

Diagnosis relies on clinical observation and eye movement recordings. Tests include videonystagmography or caloric testing; imaging (MRI) to assess central causes; vision testing and assessment of refractive error.

Management aims to treat the underlying cause and optimize vision. Refractive correction, prisms, or contact lenses can help. Medications such as gabapentin or baclofen may reduce nystagmus in some cases. Botulinum toxin injections into extraocular muscles or surgical procedures to shift the null point may be considered in selected patients. Vestibular rehabilitation and the use of low-vision aids are also used.