Large-angle exotropia corrected by intraoperative botulinum toxin A and monocular recession resection surgery

Surgical correction of large-angle exotropia, greater than 70 PD, traditionally requires operating on three or four horizontal muscles. However, in secondary exotropia from monocular visual loss, it is advisable to operate only on the eye with poor vision. We used intraoperative botulinum toxin as an adjunct to the monocular recession-resection procedure for large-angle sensory exotropia, therefore operating only on the visually impaired eye.

Three patients underwent monocular recession (10 mm) and resection (10 mm) along with intraoperative botulinum toxin A injection of 10 units into the recessed muscle. All had desired cosmetic repair of long-standing large-angle exotropia (range 100 to 110 PD) with amblyopia and vision worse than 20/200 in the deviated eye.

Within 4 days after operation all patients demonstrated maximal paresis of the lateral rectus muscle. This lasted 8 to 12 weeks and resulted in stable orthotropia at 2.5 years in case 1 and stable 8 PD exotropia at 4 years in case 2. The third case demonstrated a stable 18 PD exotropia by 7 months with a satisfactory cosmetic result.

This technique provides an alternative for the surgical correction of large-angle exotropia by operating only on two horizontal muscles. In sensory exotropia it also avoids subjecting a normal eye to an operative risk.