Effectiveness of interventions for convergence insufficiency: an observational study evaluating clinical outcomes and health-related quality of life using AS20.

Background: Convergence insufficiency (CI) is a common condition that can impair visual performance and comfort during close visual work. This observational study evaluated the effectiveness of interventions on clinical outcomes and health-related quality-of-life using the Adult Strabismus-20 (AS20) questionnaire in patients with CI.

Methods: Data was extracted from a database collected at first consultation from 2015 to 2022. Demographics, interventions and outcomes of 75 patients with CI (mean age 47.2 ± 24.7 years) were analysed.

Results: Orthoptic exercises were prescribed to 58% of patients, 28% received prisms and 9% received no treatment. At the latest follow-up review, 24% were recommended to continue exercises, 24% had prisms, 1 underwent bimedial resection and 1 had treatment with Botulinum Toxin A (BTXA). The median follow-up was 5.0 (0-55) months, 100% were discharged with 25% following failure-to-attend and 11% died. At the latest follow-up, the attendance failure rate was higher for exercises (36%) than for prisms (10%). Both near-prism cover test and near-point of convergence improved from a median of 12 (95% CI 10-14) prism dioptres (PD) to 8.5 (95% CI 6-12) PD, and 17.5 (95%CI 15-20) cm to 10.0 (95%CI 8.3-12.0) cm respectively (p < 0.05). Near-prism fusion range also improved from 10(95%CI 8-14) PD to 16(95% CI 12-20) PD (p < 0.05). The median AS20 score at presentation were 100/100 (30-100) and 47.5/100 (0-100), and post-intervention were 100/100 (75-100) and 70/100 (12.5-97.5) for psychosocial and functional components, respectively.

Conclusion: This cohort offers valuable insights into the real-life clinical management of CI in a tertiary adult strabismus centre. However, the study also found that long-term compliance with treatment is intrinsically challenging, emphasising the importance of disease education.