What results from jerky undulating eye movements?

• A. Strabismus
• B. Ptosis
• C. Nystagmus
• D. Diplopia

Answer: (C)

Nystagmus is the term for involuntary, rhythmic eye movements. When you see jerky, undulating eye motion, you’re observing nystagmus. It typically features a fast, corrective (quick) movement in one direction with a slower drift back, and it can be horizontal, vertical, rotary, or a combination. This pattern signals a disturbance in the vestibulo-ocular reflex circuits that coordinate eye movement with head motion, which is why it appears in vestibular or neurologic contexts.

Strabismus involves eyes misaligned relative to each other, which can cause double vision but isn’t described as ongoing jerky motion. Ptosis is simply drooping of the eyelid, and diplopia is the perception of two images, not a characteristic eye movement pattern.