The role of botulinum toxin A in acute-onset esotropia

Objective: To establish the effectiveness of botulinum toxin A (BTXA) in the treatment of patients with acute acquired concomitant esotropia. Design: Retrospective, interventional, noncomparative case series. Participants: Fourteen patients presenting to the Strabismus and Pediatric Service at Moorfields Eye Hospital with acute-onset esotropia over a 6-year period (1991-1997), Intervention: 2.5 units of BTXA injected into the unilateral medial rectus muscle of the deviating eye under electromyographic control. Main Outcome Measures: Pre- and postinjection angle of deviation, pre- and postinjection stereopsis, final level of stereopsis achieved, and whether corrective squint surgery was later required. Results: Fourteen patients were identified, of whom eight were male and six female. The mean age at presentation was 5.4 years, and the average time from onset to attending the clinic was 18 weeks. The mean time from onset of acute esotropia to injection was 32.5 weeks, All patients, except one, showed considerable improvement in their manifest deviation after one injection of BTXA. Eight patients (57%) maintained high-grade stereopsis of 120 seconds of are or better and long-term ocular alignment with toxin treatment alone. In total, 11 patients (79%) gained improved stereopsis and maintained satisfactory ocular alignment with toxin therapy and did not require squint surgery. Two patients (14%) did not maintain a stable ocular position after toxin treatment and later required squint surgery, gaining good ocular alignment and high-grade stereopsis. The one patient who did not respond to the initial BTXA injection refused all further treatment. The mean follow-up time was 22 months. Conclusions: Botulinum toxin therapy has a definite role in the treatment of children with acute-onset esotropia. It may well obviate the need for squint surgery. The safety and ease of administration of this treatment add to its merits.