Commentary on the Outcomes of Inferior Oblique Muscle Weakening in Inferior Oblique Muscle Overaction

289 Soltan Sanjari et al[1] are to be commended on their paper “Surgical treatments in inferior oblique muscle overaction”. They report on a retrospective study of the treatment for inferior oblique overaction (IOOA) performed over a 10‐year period on 122 eyes utilizing three different surgical techniques to weaken the inferior oblique muscle. Disinsertion on 12 eyes, myectomy on 91 eyes, and anterior transposition of the inferior oblique on 19 eyes. They judged success to be a result of better than + 1 IOOA postoperatively, finding that all three procedures had similar success rates not statistically different assessed by this metric at 91.7%, 97.8% and 89.5% respectively in the disinsertion, myectomy and anterior transposition groups. The authors note two conflicting studies comparing myectomy with anterior transposition. Min et al performed a prospective comparison of the two procedures in 20 children with + 3 bilateral overacting inferior oblique muscles. They performed an anterior transposition procedure in one eye as compared to a myectomy procedure in the other eye. They defined success differently from this study, as 0 IOOA postoperatively. Eighty‐five percent of the anterior transpositions were successful by this metric while only 25% of the myectomy group were successful.[2] Ghazawy et al reported on 120 eyes of 81 patients in a retrospective case series, of which 20 had anterior transposition of the inferior oblique, and 100 eyes underwent myectomy. In this study the authors found no statistically significant difference between myectomy and anterior transposition in both primary and secondary IOOA.[3] This current study is unique as in no previous study has disinsertion been compared to myectomy and anterior transposition for IOOA. While the authors found no statistical difference between the three procedures, it is important to point out a few caveats. Selection bias must be considered in any retrospective study. In this study, the myectomy and anterior transposition groups seem quite similar whereas the disinsertion group seems dissimilar. Table 1 presents the difference in age between the three groups at 19.1 ± 17.7, 12.5 ± 11.2 and 10.6 ± 8.9 years for the disinsertion, myectomy and anterior transposition groups respectively does not show a statistical difference (P = 0.126).[1] Though differences in age were not shown to be statistically significant, the relatively small sample size may have prevented a true difference from being shown. In Table 3, when looking at the three procedures, there is a significant difference between mean IOOA preoperatively between the three groups with the disinsertion having IOOA of +1.33 ± 0.65, +1.93 ± 0.89 for myectomy, and +2.52 ± 0. 9 for anteriorization with a highly significant p value (P = 0.001).[1] This implies that disinsertion tended to be used for lesser degrees of IOOA while anterior displacement tended to be used for larger amounts of IOOA and myectomy for intermediate levels. As shown in Table 4, when comparing these three groups, no patients with +4 IOOA had disinsertion as a procedure, and no patients with + 1 IOOA had anterior displacement as a procedure.[1] For patients with + 3 IOOA, disinsertion, myectomy and anterior transposition had a mean change of −2 ± 0.02, −2.7 ± 0.45 and − 2.5 ± 0.57 in IOOA, which with a P = 0.28 was not shown to be a statistical difference. Small sample size, however, may have prevented a true difference from being seen. For patients with + 2 IOOA the mean changes were respectively − 2 ± 0.01, −1.9 ± 0.3, and − 1.6 ± 0.57 with a P = 0.5 showing no statistical difference. This seems more convincing. The authors did a nice job comparing disinsertion, myectomy and anterior displacement of the inferior oblique as surgical treatments for IOOA. Their data seems to show that for lesser amounts of IOOA the three procedures perform similarly. For larger amounts Editorial