Assessment of Ocular Torsion in Exotropic Patients Following Horizontal Strabismus Surgery: A Comparative Analysis Using Conventional Color Fundus Photography and Spectralis Optical Coherence Tomography.

Abstract

Purpose: To objectively evaluate ocular cycloposition using conventional color fundus photography (CFP) and Spectralis optical coherence tomography (OCT) in exotropic patients undergoing horizontal strabismus surgery and to assess the agreement between these methods. Additionally, we aimed to determine whether surgery alters ocular torsion in pure exotropia. Methods: In this prospective, single-center study, 42 eyes from 21 patients with exotropia requiring bilateral lateral rectus muscle recession were evaluated. The disc-center fovea angle (DFA) was measured pre- and postoperatively using CFP (Topcon fundus camera) and Spectralis OCT with fovea-to-disc (FoDi) alignment software. Results: The angle of exodeviation improved significantly postoperatively, from 35.10 ± 7.89 to 3.76 ± 3.73 prism diopters (p < 0.001). Both CFP- and OCT-derived DFA values remained stable in both eyes at 6 months (p > 0.05 for all comparisons). No significant differences were observed between CFP and OCT measurements at baseline or postoperatively (p > 0.05). Preoperative intraclass correlation coefficient (ICC) between methods was strong (right eye: 0.765; left eye: 0.750), decreasing postoperatively to moderate levels (right eye: 0.618; left eye: 0.661). Conclusion: Horizontal strabismus surgery does not significantly alter ocular torsion in pure exotropia. Spectralis OCT reliably quantifies cyclotorsion but may yield marginally lower DFA values compared to CFP, despite no statistical difference.