Adjustable graded augmentation of superior rectus transposition for treatment of abducens nerve palsy and Duane syndrome.

[PURPOSE] To report the results of adjustable graded augmentation of superior rectus transposition, a novel modification of superior rectus transposition (SRT) designed to reduce postoperative vertical or torsional diplopia.

[METHODS] The medical records of patients who underwent adjustable graded augmentation of SRT with or without adjustable medial rectus recession (MRc) from February 2017 to December 2019 were reviewed retrospectively. A Mendez ring was used to monitor torsional change after transposition of the superior rectus muscle to the lateral rectus muscle and after sequential placement of 2 or 3 augmentation sutures by superior rectus-lateral rectus loop myopexy. If excessive mechanical intorsion was induced, the responsible augmentation suture was severed intraoperatively. If torsional or vertical diplopia was noted after recovery, the distal-most augmentation suture was cut. Exotropia was managed by severing the distal-most augmentation suture or by medial rectus adjustment.

[RESULTS] A total of 8 patients who underwent adjustable graded augmentation of SRT were included (6 using the 3-suture technique): 3 for esotropic Duane syndrome, 2 for abducens nerve palsy, 1 for Moebius syndrome, and 2 for combined trochlear and abducens nerve palsies. Of the 8 patients, 4 had prior strabismus surgery, and 1 patient had previously undergone treatment with botulinum toxin. Severing one augmentation suture in 3 cases resolved vertical (n = 2) or torsional (n = 1) diplopia and consecutive exotropia (n = 2), resulting in excellent alignment and reduction of torticollis to ≤4° in 7 cases. The technique proved insufficient in 1 patient, who had undergone 3 prior strabismus procedures.

[CONCLUSIONS] In this study cohort, adjustable graded augmentation of SRT effectively managed the risk of postoperative vertical or torsional diplopia.