Convergence insufficiency (CI) is the most prevalent of binocular dysfunctions. A prime finding in the diagnosis of CI is the near point of convergence (NPC).
The NPC was measured six different times on the same 539 children, once in the fall and once in the spring, over the course of 3 years. At each evaluation, the NPC was performed three consecutive times. An accommodative target was used in the testing and the breaks and recoveries were carefully measured and recorded to the nearest centimeter. Normative data for the break and recovery finding were calculated.
We found that the NPC measures receded significantly over three consecutive tests. The recession was not considered clinically significant for either the break or recovery measures. When various break and recovery findings were compared with reported symptoms, it was discovered that one of the break findings statistically predicted the symptomatic group from the asymptomatic group.
The NPC break and recovery does not change appreciably with multiple administrations of the test in the same test period. The criteria for a NPC break score to differentiate the more symptomatic and less symptomatic, elementary school children on the average should be 5 cm, or less. The NPC break and recovery criteria described here should be tentatively used as one of the benchmarks in the diagnosis of convergence insufficiency.