Botulinum Toxin Injections in Infantile Esotropia: Tailored Management Strategies in a Case series

Abstract Purpose: To investigate the impact of a single dose of botulinum toxin on infantile esotropia. Methods: This retrospective observational case series reviewed data from infants with esotropia who received 5 IU/0.05 mL botulinum toxin in both medial rectus muscles without EMG control. The study included five patients and any complications related to the injection or the toxin itself were documented. Throughout their regular follow-up, parents were instructed to patch the dominant eye whenever fixation preference was observed, whether in the exotropia or esotropia phase. The patients underwent examinations between their 78th and 96th months to evaluate their current visual acuity and identify any late-term accompanying squints, nystagmus, or signs of amblyopia. Best-corrected visual acuity was assessed using Snellen optotypes or pictures. Results: Five patients were included in the study. Inferior oblique muscle hyperfunction developed postinjection in all patients, occurring as early as the 7th month and as late as the 88th month. During the final examination, visual acuity was assessed. Among those with orthophoria, one patient exhibited 1.0/1.0 visual acuity, another had 0.4/0.6 visual acuity, and one had 0.2/0.2 visual acuity. In patients with monocular esotropia, the strabismic eye had a visual acuity of 0.1, while the dominant eye had a visual acuity of 1.0. Notably, none of the patients developed dissociated vertical deviations (DVD) or latent nystagmus. Conclusions: Intervention with botulinum toxin can prevent latent nystagmus and the consequent DVD by suppressing monofixation syndrome.