Botulinum toxin augmentation of medial rectus muscle recession was reported in three previous studies. Khan reported 8 patients with > 60 prism diopters (PD) esotropia treated with botulinum-augmented horizontal muscle surgery.Six of 8 had deviations of 10 PD or less following surgery, with an average follow-up of 9 months. Özkan and associates used botulinum augmentation in a group of older patients (age range 5-50 years) with large-angle esotropia of different etiologies, with a success rate of 57% and an average follow-up of 14 months.Lueder and associates evaluated the long-term outcomes in patients with infantile esotropia who had been followed for more than 2 years after treatment. The results were good, with a 74% success rate.This study demonstrated that this procedure is an effective treatment for infants with large-angle infantile esotropia, with stable results over time. Based on historical comparisons, it appears equally as effective as 3- or 4-muscle surgery and more effective than large bilateral medial rectus recessions alone.