Modified superior oblique intrasheath tenectomy in A-pattern with superior oblique overaction

BACKGROUND: To evaluate the effect of modified superior oblique intrasheath tenectomy (MSOIT) on superior oblique overaction (SOOA) with A-pattern. METHODS: We retrospectively reviewed the data of 66 patients (130 eyes) with SOOA and A-pattern underwent MSOIT at the nasal border of the superior rectus under an operating microscope between January 1, 2004 and December 31, 2018. The superior oblique (SO) tendon fibres were resected, and the sheath was preserved in all patients. The preoperative and postoperative SOOA, objective torsion, ocular motility, and A-pattern deviation findings were compared. The correlation between the preoperative A-pattern deviation and the corrected deviation was analysed. The average follow-up period was 33.45 ± 29.88 (range: 12–122) months. RESULTS: The mean SOOA deviation improved from 2.95 ± 0.54 to 0.34 ± 0.55 (P < 0.001), while the A-pattern deviation difference between upgaze and downgaze improved from 23.15 ± 7.59 prism diopters (PD) to 3.50 ± 2.90 PD (P < 0.001). The average objective fundus intorsion value improved from + 2.96 ± 0.58 to + 0.38 ± 0.60 (P < 0.001). The magnitude of correction in A-pattern was significantly correlated with the preoperative severity of A-pattern (r = 0.812, P < 0.001). CONCLUSIONS: MSOIT at the nasal border of the superior rectus (SR) under an operating microscope is safe and yields beneficial outcomes in patients with SOOA and A-pattern.