AIM: To compare the consistency and feasibility of objective ocular torsion measured with GMPE module-based optical coherence tomography(OCT)and fundus color photography(FCP).

METHODS: Patients were enrolled in our strabismus clinic from December 2020 to March 2021, and the objective ocular torsion of the eyes was measured by both GMPE module-based OCT and FCP on the same day. FCP was used to measure the fovea-disc angle(FDA)manually by using the Adobe Photoshop software, while the GMPE module-based OCT software positioned automatically the macula and the center of the optic disc to measure the FDA.

RESULTS: Fifty-five patients were included, the FDA measured by OCT was -6.6°±4.5° in the right eye and -8.8°±4.7° in the left eye, respectively; The FDA measured by FCP was -6.6°±4.7° in the right eye and -8.4°±4.1° in the left eye, respectively, with no statistically significant difference between the results of the two methods(P_{right eye}=0.90, P_{left eye}=0.08). In patients with exotropia, the FDA measured by OCT was -5.8°±4.9° in the right eye and -9.1°±4.5° in the left eye, respectively, the FDA measured by FCP was -5.7°±5.0° in the right eye and -8.6°±4.3° in the left eye, respectively,(P_{right eye}=0.75, P_{left eye}=0.15). Similarly, the patients with esotropia, the FDA measured by OCT was -9.0°±7.3° in the right eye and -11.3°±3.5° in the left eye, respectively, while the FDA measured by FCP was -10.0°±7.0° in the right and -10.1°±2.8° in the left eye(P_{right eye}=0.21, P_{left eye}=0.10), respectively. There were no significant differences between the two methods in patients with esotropia or exotropia(P>0.05). The results of both Pearson test and Bland-Altman analysis were highly correlated(r_{right eye}=0.93, r_{left eye}=0.94, P<0.01).

CONCLUSION: GMPE module-based OCT can be used for objective ocular torsion measurement with high reliability and reproducibility, and is a promising clinical alternative to the fundus color photographic method.