Efficacy of Botulinum Toxin Type A for Acute Acquired Comitant Esotropia: An Age-Stratified 2-Year Follow-Up Study.

[PURPOSE] To assess and compare the 2-year follow-up efficacy of botulinum toxin type A (BTXA) in the treatment of acute acquired comitant esotropia (AACE) across five age groups.

[DESIGN] Retrospective clinical cohort study.

[METHODS] A total of 276 patients with AACE who received BTXA injections were enrolled from a single institution between January 2019 and January 2023 (Notably, surgery was recommended for patients >12 years with large-angle esotropia (>50 prism diopters) to reduce failure or recurrence risk). Patients were stratified into five age groups based on intervention age: ≤6 years, >6 to ≤12 years, >12 to ≤20 years, >20 to ≤30 years, and >30 years. The primary outcomes included the cumulative motor and sensory success rates across different age groups, as well as the hazard ratio (HR) for the risk of AACE relapse.

[RESULTS] The median age of the 276 participants was 18 years (interquartile range: 9-30 years), with 125 (45.29%) being female. The overall 2-year motor success rate of BTXA for AACE treatment was 69.03% (95% confidence interval [CI]: 62.30%-74.81%). Notably, the motor success rate exhibited a tendency to decline with age, and patients older than 30 years showed significantly lower motor success rate compared to other age groups (≤6 years: 86.53%, >6-≤12 years: 79.96%, >12-≤20 years: 74.08%, >20-≤30 years: 67.45%, >30 years: 44.29%, Bonferroni-corrected posthoc test: P < .05/4). Similarly, patients aged >30 years demonstrated significantly lower rates of stereopsis recovery post-treatment compared to younger cohorts (Bonferroni-corrected posthoc test: P < .05/4). Furthermore, hours of near-work per day (HR: 1.09, 95% CI: 1.01-1.17) and age (HR: 1.04, 95% CI: 1.02-1.06) were identified as significant risk factors for AACE relapse following BTXA injection.

[CONCLUSIONS] In this retrospective cohort study, our findings demonstrated that younger AACE patients (≤30 years) exhibited significantly greater treatment stability and success rates following BTXA injection therapy. Postoperative preservation or achievement of normal stereopsis can serve as a reliable predictor of reduced recurrence risk.