Epithelial Thickness Mapping in Keratoconic Corneas: Repeatability and Agreement Between CSO MS-39, Heidelberg Anterion, and Optovue Avanti OCT Devices

Abstract

Purpose: To assess repeatability and agreement of corneal epithelial thickness mapping in eyes with keratoconus using three optical coherence tomography (OCT) devices featuring different technologies: spectral-domain (SD) OCT combined with Placido disk corneal topography (MS-39), swept-source OCT (Anterion), and SD-OCT (Avanti). Methods: Three consecutive measurements were acquired with the three devices in 60 eyes with keratoconus. The mean epithelial thickness was calculated in the central 2-mm zone and in 2- to 5-mm and 5- to 7-mm diameter rings. The repeatability was calculated using pooled within-subject standard deviation (S w ). The agreement was assessed by paired t tests and Bland-Altman plots. Results: The repeatability (Sw) of the epithelial thickness for the central 2-mm zone was 0.91, 0.71, and 0.93 μm for the MS-39, Anterion, and Avanti, respectively. All thicknesses with the MS-39 were greater than those of the Anterion and Avanti, with mean differences of 4.11 ± 1.34 μm ( P < .001) and 0.52 ± 1.30 μm ( P = .003), respectively. The 95% limits of agreement were 1.484 to 6.736 μm for the MS-39 and Anterion, −3.068 to 2.028 μm for the Avanti and MS-39, and 1.258 to 5.922 μm for for the Avanti and Anterion. Conclusions: Epithelial thickness mapping results were most repeatable with the Anterion, followed by the MS-39 and Avanti. The MS-39 gave the thickest values, followed by the Avanti and Anterion. The differences were significant, making the devices not interchangeable for epithelial thickness mapping in eyes with keratoconus. [ J Refract Surg . 2023;39(7):474–480.]