Surgical Outcome of Inferior Oblique Myectomy versus Recession-Anteriorization in the Treatment of Inferior Oblique Overaction.

Purpose: This study aimed to compare the surgical outcome of inferior oblique myectomy, IOM versus inferior oblique recession-anteriorization, IORA in the treatment of inferior oblique overaction, IOOA. Patients and Methods: A retrospective chart review was performed over a 12-year period, from 2009 to 2021. Eighty-nine patients diagnosed with IOOA who underwent IOM or IORA were included. The primary outcome was postoperative residual IOOA (grade 0 to +4) and percentage favorable outcome, defined as IOOA grade ≤1+ at 6 months post operation, in each group. The outcomes were compared between the two surgical procedures (IOM and IORA). The secondary outcome was the percentage of postoperative anti-elevation syndrome cases for each surgical procedure. Results: The median age at the time of surgery was 10.50 years (interquartile range, IQR: 2.83 to 28.33) in the IOM group and 5.08 years (IQR: 2.75 to 29.42) in the IORA group. The favorable outcome at 6 months was 90.91% in the IOM group, which was lower than the 95.74% in the IORA group but the difference was not statistically significant (P-value = 0.390, 95% CI: 0.07-2.82). The only surgical complication, anti-elevation syndrome, was detected in 3.77% of IOM cases and 5.80% of IORA cases, with an odds ratio of 0.64 on comparing the IOM group to the IORA group (P-value = 0.611, 95% CI: 0.11-3.62). Conclusion: These two weakening procedures are effective for treating IOOA. Although IORA seemed slightly superior to IOM in terms of favorable outcomes, the difference was not statistically significant. Moreover, the myectomy procedure was easier, was less time-consuming, had a lower risk of globe perforation and presented fewer complications such as anti-elevation syndrome.