Which statement best differentiates vergence from accommodation?

• A. Vergence adjusts image clarity; accommodation adjusts bone structure of the orbit.
• B. Vergence and accommodation are the same mechanism.
• C. Vergence adjusts eye alignment to fuse images; accommodation adjusts lens power for clear focus; they are linked but measured separately.
• D. Vergence changes pupil size; accommodation changes eye shape.

Answer: (C)

Vergence and accommodation are two distinct processes that support clear, single binocular vision. Vergence is the opposite-eye movement that rotates the eyes toward or away from each other so the images land on corresponding retinal points and fusion occurs. Accommodation is the change in the lens’s optical power to bring the object into sharp focus on the retina.

They often work together, especially when looking at nearby objects—the near response includes both vergence and accommodation (and pupil constriction) in coordination. But they can be measured separately: you can assess how much the eyes rotate to align images (vergence) independently from how much the lens changes power to focus (accommodation). That separation and their coordinated but distinct roles make them different, yet linked, in everyday vision.

The other options mix up functions or imply they are the same mechanism, which isn’t accurate.