Anterior Transposition versus Myectomy of the Inferior Oblique Muscle in the Treatment of Dissociated Vertical Deviation

Anterior transposition of the inferior oblique muscle (ATIO) and myectomy of the inferior oblique muscle (MIO) are surgical methods for treating dissociated vertical deviation (DVD) and are also used in patients with coexisting inferior oblique muscle overaction (IOOA). In order to compare the outcomes of these methods, a study of ATIO and MIO was carried out on patients with DVD of at least 5 prism dioptres (PD) in the eye involved. We evaluated 73 eyes in 41 patients, of which 35 eyes were treated by ATIO and 38 by MIO. We recorded the size of preoperative and postoperative DVD, grade of the preoperative and postoperative IOOA, repeat surgeries and complications. The mean follow-up was 19.6 months in the ATIO group and 26.5 months in the MIO group, with a minimum of 6 months. In the ATIO group, the mean preoperative DVD was 13 PD and postoperative DVD was 4 PD, as compared with 15 PD and 3 PD in the MIO group. The presence or absence of IOOA had no effect on surgery outcome in either group. No serious complications of surgery were recorded. It is concluded that both ATIO and MIO are equally effective for DVD treatment regardless of the presence or absence of IOOA. When the patients also had IOOA, this was better corrected by the ATIO than the MIO procedure.