Session: Free papers Session I - Esotropia 1

​Disruption of binocularity in pediatric acute acquired concomitant esotropia: botulinum toxin, a chance of recovery?

Introduction Acute acquired concomitant esotropia (AACE) is defined by acute onset, concomitant convergent deviation and normal ocular motility. AACE may reduce the quality of life, causing diplopia and impaired stereopsis. Options for treatment include horizontal rectus muscle surgery and botulinum toxin injection. Among the pediatric population, the most effective therapy is still a matter of debate, due to the uncertainty of the ideal target patient in terms of diagnosis-to-treatment time and lack of sensorial binocularity investigation before the onset.

Methods In a retrospective cohort study, 9 patients with AACE were elected to receive bilateral/unilateral medial rectus injections of 5 units of botulinum toxin from 02/2020 to 09/2023. Median age was 7 yo, 67% boys. Median diagnosis-to-treatment time was 7 months. Angle of deviation in prism diopter (PD) and stereopsis were evaluated at baseline, at 1-, 12- and 24-week after treatment. Cosmetic success was defined as tropia less than 10 PD or phoria less than 15 PD. Functional success was defined as phoria less than 15 PD and normal binocular vision.

Results Cosmetic success rate was 55% at 1- and 12-weeks follow-up, and up to 66% at the end of the follow-up. Functional success rate was of 66% at 24-week follow-up. One patient did not maintain a stable ocular position after toxin treatment and later required squint surgery which did not solve the diplopia. The rates of overcorrection and undercorrection were found to be higher at the first follow-up (33% and 12% respectively). Diagnosis-to-treatment time was not correlated to the clinical outcomes.

Conclusions Botulinum toxin therapy is a less invasive technique in the treatment of pediatric AACE, with 66% functional success rate at 6-month follow-up. This approach allows to avoid prolonged general anesthesia and to spare muscle integrity in case of subsequent surgery. The proof of pre-onset binocularity remains a crucial point for functional success.