Convergence insufficiency symptom survey: A tool to evaluate convergence excess in young adults

To determine the effectiveness of the Convergence Insufficiency Symptom Survey (CISS) in evaluating visual symptoms in young adults with convergence excess (CE).

A cross-sectional study was performed based on a population of optometry students. Comprehensive binocular vision tests including cover test, near point of convergence, fusional vergence and accommodative amplitude, were performed. Participants were categorised into three groups: normal binocular vision (NBV), CE and CE + accommodative insufficiency (AI) (i.e., CE + AI). The CISS was administered to each participant. An analysis of variance with Bonferroni correction was performed to compare clinical measures among the three groups. A receiver-operating characteristic (ROC) curve was constructed to evaluate the ability of CISS to differentiate CE from the NBV population.

A total of 181 participants were enrolled, including 96 in the NBV group, 66 in the CE group and 19 in the CE + AI group. A significant difference in CISS score was detected between the three groups (p < 0.001). Post-hoc tests showed significantly higher CISS scores in the CE group (16.7 ± 10.8) and the CE + AI group (19.7 ± 10.9) compared with the NBV group (12.2 ± 7.8) (p = 0.01 and p = 0.005, respectively), with no difference between the CE and the CE + AI groups (p = 0.52). The ROC curve showed the CISS poorly (but significantly) differentiated CE from NBV (area under the curve = 0.62, p = 0.01). The optimal cutoff value for a CISS score to differentiate CE was 16, with sensitivity and specificity of 52% and 72%, respectively.

Young adults with CE had significantly higher CISS scores than those with NBV. Although using the CISS solely for diagnosing CE is not recommended, it can be used to provide a measure of symptoms in individuals identified as having CE based on clinical measurements.