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

PURPOSE: 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.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.