Evaluation of the efficacy of botulinum toxin injection for the treatment of infantile esotropia.

[PURPOSE] The purpose of this study was to investigate the outcomes and complications of botulinum toxin injection (BTX) as the primary treatment of infantile esotropia (IET).

[METHODS] We included patients with IET who underwent BTX from 2015 to 2020. IET was defined as esotropia present before 12 months of age, with no significant refractive error, or limitation of rotations. We defined success as a postoperative angle of 0-10 prism diopters (PD).

[RESULTS] Sixty-three patients met our inclusion criteria (38 male patients [60.3%]). The mean age was 18 ± 8 months (range: 10-26), onset 6 ± 4 months (range: 2-10), and follow-up of 29 ± 25 months (range: 4-54). Amblyopia was present in 45 patients (71.4%). Number of BTX was, 1 in 42 (66.7%), 2 in 17 (27%), 3 in 4 (4.8%), and 4 in 1 (1.6%). The 1 BTX mean dose was 7 ± 3 international unit (range: 4-10) and a mean duration of 4 ± 1 min (range: 3-5). The mean preoperative angle of deviation was 42.30 ± 13.73 PD. The mean postoperative angle of deviation was 16.07 ± 16.15 PD ( = 0.0001). At the final follow-up, BTX was successful in 32 (51%) (success after 1st BTX 33.3%, 2nd BTX 46.03%, and 3rd BTX 50.79%). Twelve patients (19%) had undergone surgery due to the failure of BTX. Postoperative observations included transient ptosis 29 (49.2%), transient exotropia 36 (57.14%), inferior oblique overaction 13 (20.6%), vertical deviation 8 (12.7%), and persistent ptosis 1 (1.6%).

[CONCLUSION] The success rate of BTX for IET was 51%. BTX can be offered as an alternative to surgery to those who cannot undergo prolonged anesthesia or where accurate measurements could not be obtained.