Inferior oblique graded marginal myotomy versus myectomy for treatment of inferior oblique overaction.

Purpose: To evaluate and compare the surgical outcomes of inferior oblique marginal myotomy versus myectomy for treatment of inferior oblique overaction (in terms of correction of upshoot on adduction, V pattern, vertical deviation, torsion, and abnormal head posture) and document any encountered complications.

Methods: Thirty-nine patients (78 eyes), having bilateral inferior oblique overaction, were included in a randomized prospective study, to compare inferior oblique marginal myotomy (Group O, 26 patients/52 eyes) to myectomy (Group E, 13 patients/26 eyes). Group O was further divided into subgroups Z and M, 26 eyes each. Subgroup Z underwent inferior oblique Z (2 cuts) myotomy to treat grade 1 or 2 inferior oblique overaction, while subgroup M underwent inferior oblique M (3 cuts) myotomy to treat grade 3 or 4 inferior oblique overaction, thus termed "graded marginal myotomy".

Results: A successful outcome was achieved in 25/26 patients (96.2%) in Group O and 9/13 patients (80.8%) in Group E, P = .035, after 6 months of postoperative follow-up. Inferior oblique graded myotomy could correct up to +4 inferior oblique overaction and up to 30 ∆ of hypertropia, with elimination of head posture in all cases. No complications were encountered in any case.

Conclusion: The novel inferior oblique M-myotomy extended the application of marginal myotomy for cases of marked inferior oblique overaction and large hypertropias, with outcomes significantly superior to myectomy.