Near and distance vergence facility provides complementary clinical information in concussion-related convergence insufficiency.

PURPOSE: To compare near and distance vergence facility testing in adolescents and young adults with concussion-related convergence insufficiency and evaluate changes following office-based vergence/accommodative therapy (OBVAM).

METHODS

This secondary analysis of the CONCUSS randomized clinical trial evaluated vergence facility at near (40 cm) and distance (4 m) using a 12Δ base out/3Δ base in prism flipper. Participants aged 11-25 years with concussion-related convergence insufficiency were randomized to immediate or 6 weeks delayed OBVAM. Vergence facility was assessed at baseline, outcome time 1 assessment (after 12 therapy sessions for the immediate group and 6 weeks of watchful waiting for the delayed group), and outcome time 2 assessment (after both groups completed 16 therapy sessions). Agreement between near and distance vergence facility classifications was evaluated, and treatment-related changes were compared between groups.

RESULTS

Of the 106 enrolled participants, 102 completed all study visits. At baseline, the near and distance vergence facility classifications demonstrated substantial discordance. Among 101 participants with both measures available, 49 demonstrated reduced distance vergence facility despite normal near vergence facility, whereas only two showed the opposite pattern (Cohen's κ = 0.12; p < 0.0001). Vergence facility improved following therapy in both treatment groups, with larger early improvements in the immediate-treatment group.

CONCLUSIONS

Near and distance vergence facility testing provided complementary rather than interchangeable clinical information in adolescents and young adults with concussion-related convergence insufficiency. Both measures improved following vergence/accommodative therapy, supporting consideration of both testing distances in clinical assessment.