Session: Free papers Session VI - Vertical Strabismus

Modified Nishida Procedure versus Single Horizontal Muscle Transposition in Monocular Elevation Deficits

INTRODUCTION: Management of patients with monocular elevation deficits (MED) poses a challenge because of the difficulty to improve the alignment without compromising the downgaze. This study aims to compare the outcomes of 2 modalities for the management of MED: modified Nishida procedure (MN) and single horizontal muscle upward transposition (SHMT).

METHODS: A retrospective review was conducted on patients who had intervention for MED. Patients were divided into 2 groups; MN group in which both the medial and lateral rectus muscle bellies were fixated to the sclera above the horizontal meridian without disinsertion or splitting of the muscle bellies and SHMT group in which either the lateral or medial rectus muscles were disinserted and fully transposed adjacent to the insertion of the superior rectus muscle, together with an augmentation suture. Ductions, versions, fundus torsion, and angle of deviation were analyzed before and after surgery.

RESULTS: Thirty-two patients were identified; 12 in the MN group and 20 in the SHMT group. Mean age was 13.8 ± 13.5 (range, 1 to 51 years). Mean preoperative vertical angle of deviation was 24 ± 8 PD in MN group and 24 ± 6 PD in the SHMT. Ipsilateral inferior rectus recession was performed in 3 patients in the MN group and 17 patients in the SHMT group. Mean follow-up was 8.5 ± 8.2 months. The postoperative improvement of elevation in adduction and abduction was comparable in both groups (P= 0.47 and 0.16, respectively). Deficits in depression occurred in 3 patients (25%) in the MED group and 1 patient (5%) in SHMT group (P= 0.14). Deficits in abduction occurred in 1 patient (5%) in the SHMT group. No change in fundus torsion occurred with SHMT. Mean postoperative vertical angle was significantly lower (P = 0.009) in the SHMT group (0 vs 3 PD).

CONCLUSIONS: Both MN and SHMT procedures were equally effective in improving the elevation in MED. Postoperative vertical deviation was slightly smaller with SHMT.