Botulinum Toxin A for Management of Consecutive Exotropia: Factors Affecting Treatment Success

Abstract

Purpose: To assess the efficacy of botulinum toxin type A injection as a re-treatment procedure in patients with consecutive exotropia. Methods: The medical records of 34 patients who underwent botulinum toxin type A injection for consecutive exotropia were retrospectively reviewed. Five units of botulinum toxin type A was applied to the unilateral lateral rectus muscle, and the injection was administered under electromyography guidance. Successful motor alignment was defined as a far deviation within 10 prism diopters (PD). Results: A total of 34 patients were included in the study. Twenty-six patients (76.5%) had acquired esotropia and 8 patients (23.5%) had infantile esotropia. The average age of the patients was 169 +/- 88.9 months. The mean time elapsed between the last surgery and botulinum toxin injection was 67.8 +/- 78 months. The mean before botulinum toxin type A injection deviation was 20.03 +/- 8.42 PD at near and 21.41 +/- 8.87 PD at distance. The deviation after botulinum toxin type A injection was 9.65 +/- 7.42 PD at near and 10.82 +/- 7.33 PD at distance. All patients were followed up for 19.8 +/- 20 months. The average number of injections was 1.6 +/- 1.1. The final success rate was 73.5%. The first month's near deviation was significantly associated with treatment success (P = .012). Post-injection fusion potential had a weak association with the 6-month and overall treatment success (P = .073 and .057, respectively) Conclusions:The results of this study demonstrate that botulinum toxin type A injection can be an effective, safe treatment option in consecutive exotropia.