A high AC/A ratio is most likely to cause which near-vision finding?

A high AC/A ratio is most likely to cause which near-vision finding?

• A. Exophoria at near
• B. Esophoria at near
• C. Hyperopia
• D. Myopia

Answer: (B)

Understanding how accommodative convergence relates to accommodation is key. A high AC/A ratio means more convergence occurs for each diopter of accommodation. When looking at near, the eye must accommodate more, and the extra accommodation triggers disproportionately more convergence. That heightened inward turning of the eyes manifests as esophoria at near (and can sometimes progress to accommodative esotropia). Hyperopia or myopia are refractive errors and aren’t directly caused by the AC/A ratio. Exophoria at near would indicate too little convergence, which isn’t what a high AC/A ratio produces.

Understanding how accommodative convergence relates to accommodation is key. A high AC/A ratio means more convergence occurs for each diopter of accommodation. When looking at near, the eye must accommodate more, and the extra accommodation triggers disproportionately more convergence. That heightened inward turning of the eyes manifests as esophoria at near (and can sometimes progress to accommodative esotropia). Hyperopia or myopia are refractive errors and aren’t directly caused by the AC/A ratio. Exophoria at near would indicate too little convergence, which isn’t what a high AC/A ratio produces.