Corneal thickness mapping by 3D swept‐source anterior segment optical coherence tomography

Abstract

To assess accuracy and repeatability of central corneal thickness (CCT) measurements obtained by swept-source anterior segment optical coherence tomography (AS-OCT), spectral-domain retinal OCT with corneal module and ultrasound pachymetry (USP), and to assess repeatability of pachymetric mapping with AS-OCT. 50 healthy volunteers were recruited. A single, experienced operator analysed the right eye of each participant twice in the same session with AS-OCT ('corneal map' routine), retinal OCT and USP. CCT measurements were compared using repeated-measures analysis of variance, Bonferroni test, Pearson correlation and Bland-Altman plots. Repeatability of thickness maps and CCT measurements were assessed using Alpha of Cronbach, intraclass correlation coefficient (ICC) and coefficient of repeatability. Mean CCT±SD was 540±28.9 μm for AS-OCT, 544±29.5 μm for retinal OCT and 549.3±31.7 μm for USP; the differences were statistically significant (p<0.01). CCT measurements obtained with the three instruments were highly correlated: r was 0.965 for AS-OCT/USP, 0.962 for retinal OCT/USP and 0.984 for AS-OCT/retinal OCT comparison. The repeatability of CCT measurements was higher for AS-OCT than for the other devices (p<0.001). Repeatability of pachymetric maps was excellent (ICC=0.999). Pachymetric maps by swept-source AS-OCT showed excellent repeatability. CCT measurements obtained by AS-OCT, USP and retinal OCT were highly correlated although not identical.