Recession–resection combined with intraoperative botulinum toxin A chemodenervation for exotropia following subtotal ruptured of medial rectus muscle

BACKGROUND: Ruptured extraocular muscle loses its function and shows severe restriction of eye movement even after muscle-to-muscle anastomosis or muscle transposition surgery. We present the case of a patient who developed a large exotropia after near-total rupture of the medial rectus muscle following a blowout fracture. METHODS: Case report. RESULTS: A 12-year-old girl presented at our clinic with 45 prism diopters' exotropia after a blunt trauma. A forced duction test was unrestricted, and orbital computed tomography showed a medial orbital wall fracture and an impinged medial rectus muscle. Upon surgical exploration, an almost totally ruptured medial rectus muscle was found. The median margin of the ruptured muscle was 6.0 mm from its insertion, and the distal end that we could examine was 15.0 mm from the limbus. Recession-resection surgery combined with intraoperative botulinum toxin A chemodenervation to the ipsilateral lateral rectus muscle achieved a good primary alignment and binocular single visual field, even at a 9-month follow-up. CONCLUSIONS: Recession-resection surgery augmented by intraoperative botulinum toxin A chemodenervation to the ipsilateral rectus muscle appears to be highly effective in the treatment of a large exotropia produced by subtotal rectus muscle rupture following orbital wall fracture, with a lower risk of anterior segment ischemia.ope