Double-under muscle transposition: an effective surgical option for large-angle paralytic strabismus.

Purpose: To describe our surgical outcomes using a novel muscle transposition procedure, or double-under muscle transposition (DUT), in the treatment of paralytic strabismus.

Methods: In this surgery, the split halves of the superior and inferior rectus muscles opposite the paralyzed muscle are disinserted, crossed under both the remaining half and the paralyzed muscle, and anchored at opposite corners of the insertion of the paralyzed muscle. The medical records of consecutive patients who underwent DUT were retrospectively reviewed. Outcome measures were angle of deviation and duction deficit.

Results: Seven patients were included. Diagnoses included WEBINO (n = 1), rupture of the medial rectus muscle (n = 1), and abducens nerve palsy (n = 5). DUT alone was performed in 3 patients; DUT combined with antagonist muscle recession, in 4 patients. One patient underwent the surgery bilaterally. Mean follow-up was 17 ± 18+ months (range, 7-57). Preoperative angles of distance deviation ranged from 25 to 142 in magnitude. All except a single patient had duction limitation of grade -5. The mean change in distance deviation for DUT alone for each operated eye was 60 ± 6 (53-65); for combined surgery, 69 ± 23 (range, 52-103). Final mean angle of deviation at distance was +2 ± 3 (-4 to 0), although an additional surgery was required for large overcorrections in 2 patients. Duction limitation improved in all patients. One patient experienced a postoperative vertical deviation.

Conclusions: DUT may be an alternative for patients with severely paralytic strabismus not likely to resolve with previously reported muscle transposition surgeries. Overcorrection may occur in some cases.