Three-muscle surgery for large-angle esotropia in chronic sixth nerve palsy: comparison of two approaches

To report the effect of two three-muscle surgeries, inferior rectus belly transposition plus augmented superior rectus transposition plus medial rectus recession (ISM) and modified vertical rectus belly transposition plus medial rectus recession (VM), in the management of large-angle esotropia in Chinese patients with chronic sixth nerve palsy.

Twenty-eight consecutive patients with large-angle esotropia ≥50^Δ were prospectively enrolled and underwent either ISM or VM. Main outcomes included preoperative and postoperative deviation in primary position, abduction limitation and complications. Follow-up was at least 6 months.

Of the included patients, 13 underwent ISM and 15 underwent VM. Preoperatively, ISM group displayed larger esotropia and more severe abduction limitation. 27 patients completed the follow-up. The postoperative horizontal deviation and abduction limitation were similar in both groups. At the last follow-up, ISM group demonstrated greater improvement of abduction limitation than VM group in both grading (group difference -2.1, p<0.001) and quantitation (group difference 2.6 mm, p=0.001). However, eight (30%) patients revealed an induced adduction limitation ≤-1. Of the 22 patients with unilateral palsy, more esotropia of 14.8^Δ was corrected in ISM group, compared with VM group (p=0.003). Three patients (14%) developed vertical diplopia and three (14%) developed torsional diplopia. Unexpectedly, keratitis was observed in 4 of 27 (15%) patients, all with concurrent fifth and/or seventh nerve palsy. Three patients aggravated to corneal ulceration.

Two three-muscle surgeries, ISM and VM were both effective for large-angle esotropia in Chinese patients with chronic sixth nerve palsy. However, attention should be paid to potential complications.