The Efficacy of Dose Increments of Botulinum Toxin A in the Treatment of Childhood Esotropia

Abstract

Background

Botulinum toxin is known to have a powerful chemodenervation effect, and it is a well-established alternative to incisional surgery for strabismus. This study aims to investigate the efficacy of dose increments of botulinum toxin A (BTA) for the treatment of specific ranges of angle deviation.

Methods

This was a prospective study that included patients presenting with esotropia to Dhahran Eye Specialist Hospital between 2016 and 2020, who were managed by a single surgeon. Botulinum toxin was given in different dosages (2.5, 5, 7.5, 10 international units (IU)) according to the size of deviation (11–19, 20–29, 30–39, and ≥40 prism diopters (PD)), respectively. A successful outcome was defined as deviation ≤10 PD in the last visit (a minimum of 6 months) following a single injection.

Results

A total of 56 patients with esotropia were included. The mean pre-treatment angle of deviation was 38.6 ± 2.5 PD. BTA injection in a dose of 2.5 IU for the 11–19 PD angle of deviation showed the highest rate of successful outcomes (75%). According to the type of esotropia, partially accommodative esotropia showed the best response to the use of dose increments (59%). The incidence of ptosis post-BTA injection was the least (37.5%) with the smallest dose (2.5 IU).

Conclusion

BTA usage in dose increments is safe, efficient, and might be more cost-effective with less incidence of BTA associated complications. Different esotropia diagnoses have different clinical responses. However, larger studies are necessary to better predict the outcome of using dose increments.

Keywords:

• esotropia
• botulinum toxin A
• angle of deviation

Disclosure

The authors report no conflicts of interest in this work.