Effect of graded anterior transposition of the inferior oblique muscle on versions and vertical deviation in primary position

Abstract

Introduction: There are various methods for weakening the inferior oblique muscle; here we describe the results of a graded anterior transposition. Methods: Charts of 21 children (37 eyes) who underwent graded anterior transposition of the inferior oblique muscle were reviewed. Graded anterior transposition consisted of reinsertion of the inferior oblique muscle at various points along the temporal aspect of the inferior rectus muscle: the more severe the overaction, the more anterior the placement of the new insertion. In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis. We analyzed the preoperative to postoperative change in inferior oblique overaction (versions) and vertical alignment in primary position. Results: Postoperatively, 18 of 21 patients had normal versions, 2 patients had −1 underaction of 1 eye, and 1 patient had +1 overaction of both eyes. Eleven patients (15 eyes) had a preoperative vertical deviation in primary position of 4 PD or more. Three of these patients had unilateral congenital superior oblique palsy and a preoperative hypertropia of 20 PD. They underwent unilateral graded anterior transposition with a mean postoperative vertical change of 18 PD. Three patients had asymmetric primary inferior oblique overaction with true hypertropia, 1 patient had amblyopia and primary inferior oblique overaction, and 4 patients had dissociated vertical deviation associated with inferior oblique overaction. All patients had improvement after surgery, with no significant vertical deviation in primary position. Conclusions: Graded anterior transposition of the inferior oblique muscle is effective in normalizing versions and correcting vertical deviations in primary position.