An Analysis of Treatment Success of Acute Acquired Comitant Esotropia With a Single Injection of Botulinum Toxin A: An Observational Case Series Study.

Purpose: To evaluate the efficacy of a single dose of botulinum toxin A injection into the medial rectus muscle to treat acute acquired concomitant esotropia (AACE).

Methods: This observational case series study included patients diagnosed as having AACE from January 2021 to December 2023 at a tertiary eye care center in South India willing to undergo botulinum toxin injections as the first treatment who experienced sudden-onset esotropia with diplopia. Their demographics, duration of symptoms, and visual acuity were recorded. Orthoptic evaluations, including measurement of esodeviation (prism cover test) for distance and near fixation, assessment of binocularity (Worth 4-dot test), anterior and posterior segment evaluations, and cycloplegic refraction, were conducted for all cases. Neurological examinations and relevant imaging studies were performed. All participants received a predetermined botulinum toxin A dose injected into the medial rectus muscle. Evaluations were conducted at 1 week, 1, 3, and 6 months, and 1 year after injection. Main outcome measures were ocular deviation and restoration of binocularity after botulinum toxin A injection. Motor success after injection was defined as angle of deviation less than 8 prism diopters of esotropia and sensory success as absence of diplopia.

Results: A total of 72 patients were included in the study. Their mean age was 10.39 ± 5.73 years (range: 2 to 24 years) and 49 (68.1%) were male and 23 (31.9%) were female. Forty-nine (63.88%) had emmetropia, 7 (9.7%) had myopia, and 19 (26.38%) had hyperopia. After injection, the percentage of patients experiencing diplopia reduced from 79.2% at presentation (n = 57) to 18.6% at 1 week after injection (n = 13), 4.9% at 1 month after injection (n = 3), 2.2% at 3 months after injection (n = 1), and none at 6 months and 1 year after injection. Forty-two (58.3%) patients for distance and 41 (56.9%) for near attained motor and sensory success as early as 1 week after injection. Of the 28 patients who attended follow-up visits more than 1 year after injection, 85.7% maintained both motor and sensory success.

Conclusions: Botulinum toxin A is an effective first-line treatment for patients with AACE. It provides sustainable motor and sensory restoration, faster rehabilitation, and reduced need for invasive surgery in at least two-thirds of patients. .