The Effect of Botulinum Toxin Augmentation on Strabismus Surgery for Large-Angle Infantile Esotropia

Abstract Purpose To determine whether botulinum toxin augments the effect of strabismus surgery in pediatric patients with large-angle, infantile esotropia. Design : Retrospective, comparative, case series. Methods: Setting Tertiary-care pediatric hospital. Study Population Patients with large-angle, infantile esotropia. Intervention Treatment with botulinum toxin-augmented bilateral medial rectus muscle recession ("augmented-surgery group") or traditional bilateral medial rectus muscle recessions ("surgery-only group"). Main outcome measure The effect of surgery on ocular alignment at 4 months, measured in prism diopters of change per mm of surgery (PD/mm). Results There were 14 patients in the augmented-surgery group and 16 patients in the surgery-only group. The mean effect on alignment was significantly greater in the augmented-surgery group compared to the surgery-only group at 4 months (5.7 +/- 1.3 vs 4.0 +/- 1.4 PD/mm, p=0.002) and at 1 year (5.4 +/- 1.2 vs 3.7 +/- 1.2 PD/mm, p=0.002). There was a partial loss of treatment effect between 4 months and 1 year in both groups, which was similar in magnitude (p = 0.57). On linear regression, there was a trend toward a positive correlation between botulinum toxin dose and treatment effect, but this was not statistically significant (p = 0.09). Conclusions Botulinum toxin augments the surgical effect of bilateral medial rectus muscle recessions. Botulinum toxin-augmented surgery may be an alternative to traditional options for large-angle, infantile esotropia. A surgical dosing table is proposed for this technique.