Involuntary, rhythmic eye movements that can be horizontal, vertical, or rotary. It may be congenital or acquired, often indicating problems with the vestibular system, brainstem, or cerebellum.
From Greek 'nystagmos' meaning 'drowsiness' or 'nodding,' as the eye movements were thought to resemble the head movements of a drowsy person. The term entered medical vocabulary in the 19th century as ophthalmology developed as a specialty.
Nystagmus is like your eyes' GPS system going haywire - the brain loses track of where the eyes should be looking, so they constantly search for the right position! Some people with congenital nystagmus develop a 'null point' where their eyes stop moving, leading them to turn their head to an unusual position to achieve the clearest vision.
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