Relationships among Clinical Factors and Patient-reported Outcome Measures in Adults with Convergence Insufficiency

Abstract

Significance: When exploring relationships among clinical measures and patient-reported outcome measures in adults with convergence insufficiency, worse symptoms (Convergence Insufficiency Symptom Survey [CISS] score) seemed to be correlated with worse reading function domain score (Adult Strabismus-20 quality-of-life questionnaire). After treatment, improved symptoms were associated with improved reading function quality of life.

Purpose: This study aimed to explore relationships between clinical measures and patient-reported outcome measures in adults undergoing treatment for symptomatic convergence insufficiency.

Methods: In a prospective multicenter observational study, we evaluated adults with symptomatic convergence insufficiency (i.e., clinical measures of near exodeviation, receded near point of convergence, reduced near positive fusional vergence; CISS score ≥21). Fifty-seven participants treated with vision therapy/exercises (n = 35) or base-in prism (n = 22) were analyzed. Spearman correlation coefficients ( R ) were used to assess associations among the three clinical measures and patient-reported outcome measures (CISS, Diplopia Questionnaire, four Adult Strabismus-20 quality-of-life domains) before treatment (baseline) and after 10 weeks and 1 year. Associations were interpreted to be present when the lower limit of the 95% confidence interval (CI) was moderate to strong ( R ≥ 0.4).

Results: Among multiple exploratory analyses, the only moderate to strong baseline correlation was between worse CISS and worse Adult Strabismus-20 reading function scores ( R = 0.62; 95% CI, 0.43 to 0.76). Regarding change in measures with treatment, the only moderate to strong correlations were between improved CISS and improved Adult Strabismus-20 reading function scores for prism at 10 weeks ( R = 0.78; 95% CI, 0.52 to 0.91) and 1 year ( R = 0.85; 95% CI, 0.65 to 0.94) and for vision therapy/exercises at 1 year ( R = 0.78; 95% CI, 0.57 to 0.89).

Conclusions: In exploratory analyses, we found positive correlations between CISS symptom scores and reading function quality-of-life scores. The absence of correlations between symptoms and individual clinical measures is consistent with clinical experience that, in convergence insufficiency, symptoms and clinical findings can be discordant.

Trial registration: ClinicalTrials.gov NCT02510040.

Figure 1.

Association of Convergence Insufficiency Symptom (CISS) survey (CISS) scores with AS-20 Reading Function scores at enrollment. (CISS scores have been transformed so that a positive correlation indicates better CISS scores associated with better AS-20 scores.)

Figure 2.

Association of Convergence Insufficiency Symptom (CISS) survey (CISS) scores with AS-20 Reading Function scores at 10 weeks and 1 year. (A) after 1 year of vision therapy/exercises, (B) after 10 weeks of prism treatment, and (C) after 1 year of prism treatment. (CISS scores have been transformed so that a positive correlation indicates better CISS scores are associated with better AS-20 scores.)