METHODS: Eighty patients with hyperfunction who were treated in our hospital from January 2014 to December 2015 were randomly selected and treated with anterior transposition of inferior oblique muscle. Patients were followed up for 1 to 30mo. We compared the vertical incline at the original incline from far(5m), near(33cm)distance and IOOA degree before and after operations, and the correlation between the two. We also compared the vertical incline at the original incline from far(5m), near(33cm)distance and IOOA degree before and after operations in 30 eyes(20 patients)with bilateral asymmetry DVD and IOOA who received unequal inferior oblique transposition. The incidence of antielevation syndrome(AES)was observed after operations.

RESULTS: The mean prism diopters(PD)at 5m before operations was 19.5±0.15, the average PD after operations was 3.5±0.18, at 5m the original incline was 16±0.21PD. The mean PD at 33cm was 18.6±0.20 before operation, 4.5±0.26 after operations, and 14.1±0.16 at 33cm the original incline, the difference was statistically significant(P<0.05). Preoperatively, inferior oblique muscle hyperfunction +2 and +3 was 50 eyes, + 1 was 20 eyes, and 12 eyes still showed inferior oblique muscle hyperfunction after operation, but the degree of hyperactivity was +1. There was a significant positive correlation between the degree of IOOA and the vertical inclination(33cm: r=0.554, P<0.01; 5m: r=0.454, P <0.01). There were significant differences(P<0.05)in the vertical incline in 20 patients(30 eyes)with bilateral asymmetry DVD and IOOA and the degree of IOOA was significantly lower. In contrast, 18 patients(24 eyes)underwent anterior transposition of the inferior oblique muscle had AES in different degrees, which had statistically significant difference(P<0.05)compared with patients(30 eyes)with IOOA treated with unequal inferior oblique transposition.

CONCLUSION: Anterior transposition of the inferior oblique muscle has a good therapeutic effect on isolated vertical strabismus patients with inferior oblique hyperfunction. While the incidence of postoperative AES is low in patients received unequal inferior oblique muscle transposition.