Nasal myectomy of the inferior oblique muscles for recurrent elevation in adduction.

PURPOSE Recurrence of inferior oblique overaction (IOOA) after recession or anterior transposition of the inferior oblique (IO) muscles is a common problem. We have been treating such cases by nasal myectomy of the IO, where a segment of approximately 5 mm is removed from the nasal portion, leaving the temporal portion of the IO with its insertion and its ancillary origin, the neurofibrovascular junction, intact. Here we report long-term findings on this procedure. METHODS Records were analyzed on 72 eyes belonging to 40 patients with recurrent IOOA of grade +1 or more, who received nasal myectomy of the inferior oblique (NMIO) in one (8 cases) or both (32 cases) eyes, and who had a minimum of 3 months follow-up. RESULTS At follow-up (range 3.6 months to 12 years; median 26 months), 27 patients (68%) showed no IO overaction, whereas 11 (28%) showed improvement of at least one grade point and 2 (5%) showed no improvement. Of the patients with residual IO overaction, three received additional surgery: in two of these patients IO overaction was subsequently eliminated while no additional follow-up was available for the third patient. The effects of NMIO on dissociated vertical deviation were variable. CONCLUSION In 95% of these patients nasal myectomy of the IO resulted in reduction and in many cases elimination of IO overaction. An advantage of this procedure is that the temporal portion of the muscle, with its ancillary origin and insertion, is preserved.