Correlations between clinical measures and symptoms: Report 2: Accommodative and vergence measures with symptoms

The aim of this study was to explore associations among clinical measures of accommodation and vergences with symptoms, which could facilitate the validation of the Convergence Insufficiency Symptoms Survey to screen for deficient clinical measures.

Using a multi-stage random cluster sampling, 1211 high school students (481 males and 730 females) between 13 and 18 years of age were selected and examined. Visual acuity, stereoacuity and suppression, refractive errors, near point of convergence, heterophoria and fusional vergences, as well as, amplitude of accommodation, accommodative response, facility and relative accommodation were evaluated. The validity of the Convergence Insufficiency Symptoms Survey to distinguish between children with and those without anomalies in the clinical measures were characterized using the Receiver Operation Curve, sensitivity and specificity of the tests.

The overall mean and standard deviation for symptoms score was 27.38 ± 11.04. Deficient accommodative measures revealed worse symptoms scores than did deficient vergence measures and children with deficient clinical measures had significantly higher mean symptoms scores. (p = 0.001) However, the correlations between defective clinical measures and symptoms were significant but relatively weak. The Receiver Operation Curve showed that the clinical measures with the highest sensitivities using the CISS (≥16) were: reduced amplitude of accommodation 0.63, 95% Confidence interval, 0.59-0.68%) accommodative facility 0.62 (95% Confidence interval, 0.58-0.67) and near point of convergence 0.60 (95% Confidence interval, 0.53-0.67).

Deficient clinical measures and symptoms of asthenopia are prevalent and correlated in the sample of school children studied. Overall, findings suggest that high school children with deficient clinical measures may be symptomatic when they perform intense near task compared to those without deficiencies. In addition, although validated for convergence insufficiency, the Convergence Insufficiency Symptoms Survey could barely distinguish between children with and without defective clinical measures. Findings highlight the need for and provide baseline data towards possible validation of a fast and reliable screening tool for vision anomalies. Further studies on similar populations are needed to confirm these findings and add to knowledge base.