REPEATABILITY AND AGREEMENT OF TOTAL CORNEAL ASTIGMATISM MEASUREMENTS IN KERATOCONIC EYES OBTAINED BY FOUR DEVICES: ANTERION, CASIA SS-1000, IOLMASTER 700, AND MS-39

To evaluate repeatability and agreement of measurements of total corneal astigmatism (TCA) in a population of keratoconic (KC) eyes, obtained by four devices: Two swept-source (SS) optical coherence tomography (OCT)-based (Anterion and Casia SS-1000), one SS-OCT combined with reflectometry (IOLMaster 700) and one spectral-domain (SD) OCT combined with Placido disk corneal topography (MS-39)

University Hospital of North Norway, Tromsø, Norway

Øyelegesenteret, Tromsø, Norway

Three consecutive measurements were acquired with each of the four devices in 136 KC eyes. TCA values were transformed to vector components (J0/J45). The repeatability was calculated using pooled within-subject standard deviation (S_w). The agreement between devices was assessed by repeated-measures ANOVA, Bland–Altman plots, and Double-angle plots for vector difference in astigmatism

The repeatability of TCA showed S_w ≤ 0.23 D for cylinder magnitude, ≤ 0.14 D for J0, and 0.12 D for J45 for all devices. There were statistically significant differences in cylinder magnitude for every pair of devices except for IOLMaster 700 vs. MS-39 and Anterion vs. MS-39. There were no statistically significant differences in J45 for any pair of devices, but there were statistically significant differences for J0 for IOLMaster 700 vs MS-39 and Anterion vs. MS-39. The smallest mean absolute vector difference in astigmatism was between the Anterion and the Casia SS-1000 (0.55 ± 0.43 D), and the largest between Anterion and MS-39 (1.36 ± 1.32 D)

All four devices showed good repeatability in measurements of TCA in KC eyes, but there were statistically significant differences in cylinder magnitude between most devices. Future studies are waranted to evaluate the use of the four devices in refractive procedures in KC eyes