Which condition is associated with a higher AC/A ratio?

• A. Convergence Insufficiency
• B. Convergence Excess
• C. Divergence Insufficiency
• D. Divergence Excess

Answer: (B)

AC/A ratio is the amount of vergence (eye turning) that occurs for each diopter of accommodation (focusing). A higher AC/A ratio means the eyes converge much more for a given focusing effort. Convergence excess fits this pattern because the eyes over-converge for near tasks, so a small amount of accommodation triggers a disproportionately large convergence response. Clinically this shows up as stronger near convergence and often near esophoria or even a near esotropia, which aligns with a high AC/A ratio. In contrast, convergence insufficiency involves insufficient convergence at near and usually does not display a high AC/A, while divergence problems deal with the ability to diverge rather than the accommodation-induced convergence relationship. Hence, convergence excess is associated with a higher AC/A ratio.