Superior Oblique Muscle Palsy: Clinical Characteristics and Surgical Approach in 1057 Patients

Abstract Background To evaluate the clinical findings of patients with SOP who underwent surgery. Methods This historical cohort study was performed on 1057 SOP patients managed with surgery in Farabi Hospital, Iran, from 2011 to 2022. Results Unilateral SOP was found in 990 (93.7%) patients with a mean age of 21.8 ± 14.8 years [715 (72.2%) congenital and 275 (27.8%) acquired ( P < .001)]. Bilateral SOP was diagnosed in 67 (6.3%) patients with a mean age of 19.4 ± 15.6 years, in which 18 (27%) cases had masked type. The mean angle of vertical deviation in primary position at far in unilateral and bilateral cases was 15.6 ± 8.3 and 13.3 ± 9.1 △, respectively ( P < .001). In unilateral cases, abnormal head posture (AHP) was detected in 847 (85.5%) patients and 12 (1.2%) had paradoxical AHP. Amblyopia was found in 89 (9.9%) unilateral and 7 (10.3%) bilateral cases. Solitary inferior oblique myectomy, was the most common surgery in both unilateral (n = 756, 77.1%) and bilateral (n = 35, 52.2%) patients. The second surgery was performed for 84 (8.6%) unilateral and 33 (49.3%) bilateral cases (P < .001). The prevalence of amblyopia and the mean angle of horizontal deviation were significantly higher in patients who needed more than one surgery (all P < .05). Conclusion Congenital SOP was more than twice as frequent as acquired SOP and about 90% of unilateral and 50% of bilateral cases were managed with one surgery. Amblyopia and significant horizontal deviation were the most important factors for reoperation. Trial registration: The Institutional Review Board approval was obtained from the Tehran University of Medical Sciences (IR.TUMS.FNM.REC.1400.012) and this study adhered to the tenets of the Declaration of Helsinki and HIPAA.