Measurement Repeatability and Concordance of Corneal Tomography in Keratoconus Using Anterion Versus Pentacam

Purpose: This study aimed to compare the repeatability and agreement of corneal tomographic measurements between the Anterion Cornea App and Pentacam HR in keratoconus (KCN). Methods: Eyes with KCN were imaged three consecutive times with each device. Intra-device repeatability was assessed using intraclass correlation coefficients (ICCs), within-subject standard deviation (Sw), coefficient of variation (CV), and repeatability coefficients (RCs). Inter-device agreement was evaluated using concordance correlation coefficients (CCCs) and Bland–Altman analysis. Parameters included anterior and posterior keratometry values (K1, K2, Kmean, Kmax, and ΔK), central corneal thickness (CCT), and thinnest pachymetry (TP). Results: Twenty-eight eyes from 17 patients were included. Both devices demonstrated high same-session repeatability (ICC > 0.90 and CV < 5%) for all parameters except anterior ΔK and posterior ΔK. Anterion demonstrated lower measurement variability than Pentacam for all parameters. For anterior Kmax, Anterion had an RC of 1.38 diopters (D) versus 2.48 D for Pentacam. Pachymetric RCs were lower with Anterion than with Pentacam (CCT: 6.24 vs. 18.85 μm; TP: 5.93 vs. 20.34 μm). Inter-device agreement was substantial (CCC > 0.95) for most parameters except ΔK. Compared with Pentacam, Anterion measured CCT as 6.16 μm thinner and TP as 11.99 μm thinner. Bland–Altman analysis showed greater inter-device variability for all anterior keratometry parameters, posterior K1, and posterior Kmean. Conclusions: Anterion demonstrated lower same-session measurement variability than Pentacam HR, particularly for Kmax and pachymetry. Future longitudinal studies across multiple sessions are needed to assess whether Anterion’s lower same-session variability confers any advantages in KCN detection and progression monitoring. Overall, the two devices should not be used interchangeably for KCN assessment.