Extended Data Fig. 4: Repeatability of scleral birefringence measurements in guinea pigs using TRIPS-OCT.

a, Twelve guinea pig eyes were imaged repetitively with identical imaging angles. b, Linear correlation of mean values of repetitively measured birefringence. c, Bland–Altman plot of the repetitively measured birefringence. d, Repeatability test under varying imaging angles. To test the repeatability under slightly varying imaging angles, TRIPS-OCT imaging was performed repetitively on guinea pigs placed in both the prone and supine positions. Cross-sectional images indicate slightly varying retina tilt. Blood vessels indicated by white arrows are used to register the rotated birefringence images. e, Twelve eyes were imaged repetitively with prone and supine positions. f, Linear correlation of the mean values of the repetitively measured birefringence. g, Bland–Altman plot of the repetitively measured birefringence. The r values are calculated by Pearson correlation. The p values are calculated by F-test against a constant model. Excellent repeatability was achieved under slightly varying imaging angles because the retardance and diattenuation of the cornea were correctly compensated for in the reconstruction. The 1.96 SD error was 6.1% under different imaging angles, higher than the value of 2.4% under identical imaging angles, perhaps due to the slight change in scleral thickness under different tilts. SD: Standard deviation.