Objective: To report the effect of weakening the superior rectus and inferior oblique (IO) muscles on ocular rotations.
Design: Observational case series. We reviewed a 10-year period of medical records of consecutive patients who underwent bilateral 5- to 11-mm (mean, 8.0 mm; SD, 1.1 mm) superior rectus muscle recessions combined with an IO muscle recession, myectomy, or anterior transposition. The effects on ocular rotations and eyelid position were recorded for the 37 patients (69 eyes) who were followed up for at least 6 months postoperatively. Nonparametric 1-way analysis of variance was used to compare results across the 3 procedures. The setting was a subspecialty practice at an academic institution.
Results: Supraduction deficiency was significantly associated with transposition of the IO muscle anterior to the inferior rectus muscle insertion compared with the standard IO muscle recession (P = .001), and IO muscle myectomy (P = .009). Y-pattern exotropia occurred more frequently after transposition of the IO muscle anterior to the inferior rectus muscle insertion than other weakening procedures (P<.001).
Conclusion: Transposition of the IO muscle anterior to the inferior rectus muscle insertion, combined with ipsilateral superior rectus muscle recession, results in more supraduction deficiency and more frequent Y-pattern exotropia compared with standard IO muscle recession.