Reexploration and inferior oblique myectomy temporal to the inferior rectus to treat persistent inferior oblique overaction

Abstract

Persistent symptomatic inferior oblique (IO) muscle overaction (IOOA) after IO muscle weakening surgery is a common problem. We describe the results of reexploration and myectomy of the IO muscle using a standard inferotemporal approach to treat this clinical entity. A retrospective noncomparative consecutive series of patients referred for treatment of persistent IOOA. The following preoperative and postoperative measurements were recorded in each case: (1) the ductions and versions of the overacting IO muscle and its antagonist superior oblique (SO) muscle; and (2) alternate prism cover test, using loose prisms at 6 m, in primary position and right- and leftgaze. The preoperative and longer term postoperative findings were compared. Eight patients were identified. Three had previously undergone a standard IO myectomy, and five had undergone a standard IO muscle recession. The median period of postoperative follow-up was 12 months (range, 7 months to 2 years). The IOOA was eliminated in three patients and a reduction of IOOA of at least 1 unit was achieved in all patients. Seven patients showed improvement of their SO muscle underaction on versions, postoperatively. All patients achieved a marked improvement in their alignment across the three standard horizontal positions of gaze. The mean vertical deviations pre- and postoperatively was 23(Delta) versus 7(Delta) in contralateral gaze, 17(Delta) versus 4(Delta) in primary gaze, and 7(Delta) versus 1(Delta) in ipsilateral gaze. Reexploration and myectomy of the IO muscle near to the temporal border of the inferior rectus muscle is a reliable and effective way of treating persistent IOOA.