Which form increases in velocity when one eye is occluded and is commonly associated with infantile esotropia?

• A. Spasmus nutans
• B. Latent nystagmus
• C. Rotational nystagmus
• D. Gaze-evoked nystagmus

Answer: (B)

Latent nystagmus is the finding you’re looking for here. It’s a form of nystagmus that becomes more prominent in velocity when one eye is occluded, because the brain’s fixation and fusion signals are disrupted and the instability of the visual input is uncovered. This pattern is classically associated with early-onset conditions like infantile esotropia, where the visual system hasn’t developed normal binocular fusion, so monocular occlusion reveals the nystagmus more clearly. The nystagmus is typically horizontal, and can be pendular or jerk in character.

Spasmus nutans tends to show a triad of nystagmus with head nodding and torticollis, and isn’t specifically tied to occlusion. Rotational nystagmus is a rotation around an axis and isn’t described by a change with covering one eye. Gaze-evoked nystagmus appears with gaze-holding dysfunction at eccentric positions, not due to occlusion.