Vertical rectus muscle transposition with intraoperative botulinum injection for treatment of chronic sixth nerve palsy

Six adult patients with acquired, chronic, complete sixth nerve palsy had vertical rectus muscle transposition to the lateral rectus muscle insertion with intraoperative injection of botulinum toxin into the ipsilateral medial rectus muscle. Five of six patients were orthophoric in primary gaze, and the remaining patient achieved single binocular vision with a small head turn. This method compares favorably with previously described transposition procedures for sixth nerve palsy in terms of amount of correction and size of the window of single binocular vision with a lower risk of anterior segment ischemia.