Session: Poster session A

Long-term efficacy of botulinum toxin for treatment of acquired nonaccommodative comitant esotropia

Purpose: To investigate the long-term effectiveness of botulinum toxin (BTX) treatment in patients with acquired nonaccommodative comitant esotropia (ANAET) ≤ 25 prism diopters (∆).

Methods: Patients with ANAET ≤ 25∆, who received BTX injection in both medial rectus (MR) muscles without the use of electromyographic guidance and followed-up for at least 1 year were included. The distant and near deviation angles were measured at baseline, 1 year, and at the last follow-up examination after BTX injection. Treatment was considered successful if the final ocular alignment showed esophoria ≤ 6∆ at distance and near.

Results: Forty-two patients were included in this retrospective study. The mean age at treatment was 32.6±14.7 years and an average dose of BTX for the first injection was 6.7±1.3 units. An average of 2.0±1.0 injections were received for each patient and 16 patients (38%) received two or more injections. The mean esodeviation pre-injection was 13.2±5.6∆ at distance and 12.0±7.0∆ at near. The mean angle of esodeviation was 5.0±5.0∆ at distance and 4.0±5.0∆ at near at 1 year after the first injection and 4.8±5.9∆ at distance and 4.0±5.9∆ at near at final visit with an average follow-up of 2.7±1.3 years. The treatment success rate was 64.9% at 1 year and 73.8% at final visit. Ptosis and/or exodeviation ≥ 20∆ occurred in 3 patients (7.1%) at two weeks after injection, which all resolved within three months.

Conclusion: BTX injection in MR muscles is a safe and effective treatment of ANAET. These results suggest that BTX treatment can be a valuable alternative to strabismus surgery in ANAET ≤ 25∆.