Risk factors and predictors for botulinum toxin type A reinjection within six months in patients with acute acquired concomitant esotropia.

BACKGROUND

To identify independent risk factors and predictors for botulinum toxin type A (BTA) reinjection within 6 months in acute acquired concomitant esotropia (AACE) patients, providing a scientific foundation for risk-stratified clinical management.

METHODS

In this case-control study, AACE patients enrolled at Beijing Tongren Hospital (July 2021-January 2025) receiving initial BTA treatment were categorized into reinjection (n = 56) and nonreinjection (n = 61) groups based on the need for a second injection within 6 months. All participants underwent comprehensive ophthalmic and binocular vision assessments at baseline (T0), 1 month (T1), and 3 months (T2). Binary logistic regression analyses were performed to identify predictors.

RESULTS

Baseline characteristics were comparable between groups, except that anisometropia (≥ 1.0 D) was significantly more prevalent in the reinjection group. Multivariable analysis revealed that baseline anisometropia (≥ 1.0 D) was an independent risk factor for reinjection (OR = 2.789, 95% CI: 1.183-6.576). Incorporating postoperative measures, the dynamic prediction model further identified residual distance deviation at 3 months (T2), measured with full refractive correction, as a significant predictor (OR = 1.315 per prism diopter increase, 95% CI: 1.069-1.619). A prediction model combining these factors achieved an area under the curve of 0.810 (95% CI: 0.732-0.887). A cutoff of > 5.23 prism diopters for residual deviation at T2 predicted reinjection with 82.0% specificity.

CONCLUSIONS

Anisometropia is a robust baseline predictor for BTA reinjection in AACE. Residual distance deviation at 3 months postoperatively serves as a critical dynamic indicator of treatment response and reinjection risk, enabling early identification of high-risk patients.