Which finding is most likely in a basic exophoria regarding the AC/A ratio?

• A. Elevated AC/A
• B. Low AC/A
• C. Normal AC/A
• D. Variable AC/A

Answer: (C)

The AC/A ratio measures how much convergence you get for each diopter of accommodation. In a basic exophoria, the exodeviation is similar at distance and near, which means the vergence system responds to changes in accommodation in a normal, expected way. That normal coupling indicates a normal AC/A ratio. If AC/A were high, near deviation would tend to shift toward esophoria (too much convergence with accommodation); if AC/A were low, near deviation would become more exophoric (insufficient convergence). A variable AC/A would produce inconsistent near vs. distance findings, which isn’t typical for basic exophoria.