Cso Ms39 Spectral-Domain Oct Combined With Placido Disk Corneal Topography Corneal Epithelial Thickness Mapping: Repeatability And Agreement With Heidelberg Anterion And Optovue Avanti

To assess the repeatability of Corneal Epithelial Thickness Mapping (ETM) in keratoconic (KC) eyes using a novel spectral-domain (SD) optical coherence tomography (OCT) combined with Placido disk corneal topography (MS39), and to determine the agreement of the measurements with two validated devices.

Department of Ophthalmology, University Hospital North Norway, Tromsø, Norway

Øyelegesenteret, Tromsø, Norway

Analysis of 60 KC eyes was performed. Three consecutive measurements of each eye were acquired with MS39,  Anterion SS-OCT and Avanti SD-OCT devices, and averages of the ETMs were calculated in the central 2 mm zone as well as in the 2-5 mm and 5-7 mm diameter rings. The repeatability was analyzed using pooled within-subject standard deviation (S_w). The agreement was assessed by paired t-tests and Bland-Altman plots.

The repeatability ranges of MS39, Anterion and Avanti ETM measurements in KC eyes were: S_w: 0.78 - 1.37 μm , 0.71 - 1.59 μm and S_w: 0.75 - 1.79 μm, respectively. All the values of the thickness measurements with MS39 were higher than Anterion’s with the mean differences of 2.59 ± 1.15 μm (p < 0.001), but lower than Avanti’s with mean differences of 0.99 ± 1.17 μm (p < 0.001). The 95% limits of agreement (LoA) were: for MS39 and Anterion, 0.336 - 4.844, for Avanti and MS39, –1.303 - 3.283, and for Avanti and Anterion, 1.258 - 5.922.

The repeatability of the MS39’s ETM was lower than Anterion’s but higer than Avanti’s. In terms of the agreement, the epithelium measured by the MS39 was always thicker than Anterion but thinner than Avanti, making their interchangeability unsuitable without corrections.