The amount of accommodation change in vergence accommodation is determined by which ratio?

The amount of accommodation change in vergence accommodation is determined by which ratio?

• A. CA/CR ratio
• B. CA/C ratio
• C. CR/CA ratio
• D. DA/AC ratio

Answer: (B)

Convergence can drive the lens to change focus, a cross-link in the visual system called convergence accommodation. The amount of that accommodation change is captured by the CA/C ratio: how many diopters of accommodation are elicited for each unit of convergence (per prism diopter or per degree). In other words, CA/C tells you how strong the accommodation response is when the eyes converge. This is different from the opposite direction, where accommodation influences vergence, described by the AC/A ratio. So for understanding how much accommodation changes due to vergence, CA/C is the measuring ratio.

Convergence can drive the lens to change focus, a cross-link in the visual system called convergence accommodation. The amount of that accommodation change is captured by the CA/C ratio: how many diopters of accommodation are elicited for each unit of convergence (per prism diopter or per degree). In other words, CA/C tells you how strong the accommodation response is when the eyes converge. This is different from the opposite direction, where accommodation influences vergence, described by the AC/A ratio. So for understanding how much accommodation changes due to vergence, CA/C is the measuring ratio.