Efficacy of inferior oblique anterior transposition placement grading for dissociated vertical deviation

Objective: To determine if graded anterior placement of a transposed inferi or oblique muscle is beneficial for treating variable amounts of dissociate d vertical deviation (DVD). Design: Retrospective, consecutive, comparative case series. Participants: Patients who underwent inferior oblique muscle anterior trans position ([OAT) for DVD at one institution between 1991 and 1999. Methods: Chart review. All patients had IOAT procedures of graded placement at 1, 2, or 3 mm anterior to the inferior rectus muscle insertion or stand ard placement at the level of the inferior rectus muscle insertion. Main Outcome Measures: The effect of graded and standard placement was asse ssed by measuring the difference between preoperative and postoperative DVD and was defined as DVD correction. The success of surgery was judged by th e residual DVD at long-term follow-up of 6 months or more. Excellent, fair, and poor outcomes were defined as residual DVD of 0 to 5 prism diopters (P D), 6 to 12 PD, and 13 or more PD, respectively. Results: Fifty-five patients (106 eyes) underwent [OAT for DVD. The compari son of DVD correction for the standard versus graded group yielded signific ance at long-term follow-up (P = 0.001). This result became nonsignificant after adjusting for preoperative DVD (P = 0.178). The power to detect a 5-P D difference between graded and standard placement was 90%. The surgical su ccess was similar for patients receiving graded and standard]OAT. Patients with 0 to 15 PD of preoperative DVD fared better than those with more than 15 PD of preoperative DVD. Conclusions: This study does not demonstrate increased correction of DVD wi th graded [OAT versus standard [OAT. We do not recommend placement of the i nferior oblique muscle anterior to the inferior rectus muscle insertion, In ferior oblique muscle anterior transposition for DVD was clinically more ef fective for smaller amounts of DVD. Ophthalmology 2001;108:2045-2050 (C) 20 01 by the American Academy of Ophthalmology.