Purpose To study the surgical outcomes of inferior oblique (IO) myectomy in patients with unilateral superior oblique (SO) palsy and mild to moderate hypertropia (≤15 PD) in the primary position. Methods This retrospective study included 36 eyes of 36 patients who underwent IO myectomy for unilateral SO palsy between 2017 and 2023. Patients with bilateral SO palsy, primary position hypertropia >15 PD, prior strabismus surgery, or SO tendon laxity on Guyton's exaggerated traction test were excluded. Hypertropia in different gaze positions, oblique muscle action, and other parameters were evaluated preoperatively and at the final follow-up. Results The mean age was 25.1 ± 13.1 years (range: 8–58), and 58% were male. Mean follow-up was 18.1 ± 9.8 months (range: 6–42). Hypertropia decreased significantly in primary and reading positions, from 10.2 ± 3.7 PD (range: 4–15) and 11.0 ± 3.8 PD (range: 5–15) preoperatively to 1.9 ± 2.3 PD (range: 0–8) and 2.2 ± 2.7 PD (range: 0–8) postoperatively ( p < 0.001). IO overaction decreased from 2.4 ± 0.9 (range: 1–4) to 0.4 ± 0.6 (range: 0–2), and SO underaction improved from −2.1 ± 0.7 (range: −3 to −1) to −0.3 ± 0.4 (range: −1 to 0) (both p < 0.001). Excyclotorsion was present in 72% preoperatively and decreased from 4.0° ± 2.8° (range: 0–8) to 1.7° ± 1.6° (range: 0–4) ( p < 0.001). Abnormal head position (AHP) was present in 26/36 patients (72%) and resolved in 81%, while diplopia was reported in 22/36 patients (61%) and resolved in 77%. Conclusion IO myectomy is a simple, effective, and safe procedure for mild to moderate hyperdeviation secondary to unilateral SO palsy; however, these findings should be interpreted in light of the study's retrospective design and modest sample size.
Omari et al. (2026) studied this question.