Which statement is true about Convergence Insufficiency and Convergence Excess?

Which statement is true about Convergence Insufficiency and Convergence Excess?

• A. Convergence Insufficiency has the higher AC/A
• B. Convergence Excess has the higher AC/A
• C. They have the same AC/A
• D. AC/A is not relevant

Answer: (B)

The idea being tested is how the accommodative-vergence link, quantified by the AC/A ratio, differs between convergence insufficiency and convergence excess. AC/A is the amount of convergence that occurs for a given amount of accommodation. In convergence excess, the vergence response to accommodation is exaggerated. Even a small amount of accommodation triggers more convergence than is appropriate for the task, so the near response is dominated by excessive convergence. This gives a high AC/A ratio, and at near you often see esophoria or over-convergence that can be reduced with lenses or prism that lower the accommodative demand. In convergence insufficiency, the system doesn’t converge adequately for near tasks, producing exophoria at near. The accommodative-driven convergence is weaker, so the AC/A ratio tends to be low or normal, meaning accommodation drives less vergence than needed. So the statement that convergence excess has the higher AC/A is the best one, because its hallmark is an elevated AC/A ratio leading to excessive near convergence.

The idea being tested is how the accommodative-vergence link, quantified by the AC/A ratio, differs between convergence insufficiency and convergence excess. AC/A is the amount of convergence that occurs for a given amount of accommodation.

In convergence excess, the vergence response to accommodation is exaggerated. Even a small amount of accommodation triggers more convergence than is appropriate for the task, so the near response is dominated by excessive convergence. This gives a high AC/A ratio, and at near you often see esophoria or over-convergence that can be reduced with lenses or prism that lower the accommodative demand.

In convergence insufficiency, the system doesn’t converge adequately for near tasks, producing exophoria at near. The accommodative-driven convergence is weaker, so the AC/A ratio tends to be low or normal, meaning accommodation drives less vergence than needed.

So the statement that convergence excess has the higher AC/A is the best one, because its hallmark is an elevated AC/A ratio leading to excessive near convergence.