Inferior oblique overaction in trochlear nerve palsy: anterior transposition versus myectomy.

Abstract Purpose To compare the effectiveness of inferior oblique myectomy and anterior transposition for correction of hypertropia in trochlear nerve palsy. Methods This retrospective study compares the surgical outcome of 40 patients with hypertropia secondary to trochlear nerve palsy who underwent either a unilateral myectomy or anterior transposition of the inferior oblique muscle. The primary outcome measure was the change in vertical deviation in primary gaze. Results A total of 40 patients with a mean age of 41 years were included. There was no statistically significant difference between groups (near preoperative hypertropia, P = 0.134 [Mann-Whitney test]). Of these, 19 underwent anterior transpositions and 21 myectomies. Both surgical techniques were successful at reducing levels of vertical deviation (anterior transposition, 89%; myectomy, 76%). However, the relative percentage reduction showed a statistically significant difference in postoperative outcomes, with anteriorization being more effective (anteriorization, 82%; myectomy 48%; P = 0.003). Conclusions In this study cohort, anterior transposition was more effective than myectomy at correcting vertical deviation in patients with inferior oblique overaction secondary to trochlear nerve palsy.