Which statement best describes Stimulus AC/A?

Which statement best describes Stimulus AC/A?

• A. Stimulus AC/A is unaffected by the amount of accommodation a person makes.
• B. Response AC/A is the same as Stimulus AC/A in all individuals.
• C. Stimulus AC/A assumes that everyone accommodates the full demand presented to them.
• D. AC/A ratios increase with age in all cases.

Answer: (C)

Stimulus AC/A looks at how much convergence (vergence) occurs for a given accommodative demand, calculated under the assumption that the eye fully accommodates to the presented stimulus. In other words, it presumes the accommodative response matches the stimulus demand. This is why the statement describing Stimulus AC/A as assuming full accommodation to the presented demand is the best fit. If someone under- or over-accommodates, the actual relationship can differ from the stimulus-based calculation, which is why the other options aren’t correct: the measure isn’t truly unaffected by accommodation, stimulus and response AC/A aren’t always identical due to individual differences, and AC/A ratios don’t universally increase with age in every case.

Stimulus AC/A looks at how much convergence (vergence) occurs for a given accommodative demand, calculated under the assumption that the eye fully accommodates to the presented stimulus. In other words, it presumes the accommodative response matches the stimulus demand. This is why the statement describing Stimulus AC/A as assuming full accommodation to the presented demand is the best fit. If someone under- or over-accommodates, the actual relationship can differ from the stimulus-based calculation, which is why the other options aren’t correct: the measure isn’t truly unaffected by accommodation, stimulus and response AC/A aren’t always identical due to individual differences, and AC/A ratios don’t universally increase with age in every case.