ABSTRACT
OBJECTIVE: To determine if graded anterior placement of a transposed inferior oblique muscle is beneficial for treating variable amounts of dissociated vertical deviation (DVD). DESIGN: Retrospective, consecutive, comparative case series. PARTICIPANTS: Patients who underwent inferior oblique muscle anterior transposition (IOAT) 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 standard placement at the level of the inferior rectus muscle insertion. MAIN OUTCOME MEASURES: The effect of graded and standard placement was assessed by measuring the difference between preoperative and postoperative DVD and was defined as DVD correction. The success of surgery was judged by the 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 (PD), 6 to 12 PD, and 13 or more PD, respectively. RESULTS: Fifty-five patients (106 eyes) underwent IOAT for DVD. The comparison of DVD correction for the standard versus graded group yielded significance 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-PD difference between graded and standard placement was 90%. The surgical success was similar for patients receiving graded and standard IOAT. 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 with graded IOAT versus standard IOAT. We do not recommend placement of the inferior oblique muscle anterior to the inferior rectus muscle insertion. Inferior oblique muscle anterior transposition for DVD was clinically more effective for smaller amounts of DVD.
