Disease specific postoperative drift patterns in vertical and torsional strabismus

Purpose To compare postoperative changes in vertical and torsional alignment and stereopsis among patients with vertical or torsional diplopia caused by thyroid eye disease (TED), superior oblique palsy (SOP), and sagging eye syndrome (SES), and to identify disease-specific postoperative patterns.Methods This retrospective study included 57 patients (25 with TED, 14 with SOP, and 18 with SES) who underwent strabismus surgery for vertical or torsional diplopia at Hyogo Medical University between January 2021 and December 2023. Vertical deviation was measured by alternate prism cover test, torsional deviation by synoptophore, and stereopsis by the Titmus stereo test (six-grade scoring). Surgical effects were defined as the change in deviation per millimeter of muscle recession. Postoperative measurements were obtained at 1 day, 3 months, and 6 months. Statistical analyses included paired t-tests, Kruskal–Wallis test, and Spearman correlation.Results Vertical deviation significantly improved from preoperative to 6 months postoperatively in all groups (TED: 29.5→5.7 PD; SOP: 26.9→5.1 PD; SES: 7.9→2.8 PD). Torsional deviation improved significantly only in SES (p = .026). Stereopsis improved significantly only in TED (p = .040). The surgical effect was greatest in TED (5.1 ± 1.9 PD/mm) and smallest in SES (2.9 ± 1.6 PD/mm) (p = .004). Improvement in vertical deviation correlated positively with stereopsis improvement (r = 0.352, p = .009).Conclusions Postoperative alignment dynamics differ among TED, SOP, and SES. Vertical alignment continues to improve for several months in TED and SOP but stabilizes earlier in SES. Recognizing these disease-specific patterns may aid in determining the optimal timing for adjustable suture adjustment or reoperation in cases of persistent vertical diplopia.