Reliability and Reproducibility of Assessment of Corneal Epithelial Thickness by Fourier Domain Optical Coherence Tomography

Abstract

To analyze the intra-user reliability and inter-user reproducibility of assessment of corneal epithelial thickness by Fourier domain optical coherence tomography. In this consecutive cross-sectional case series performed at a tertiary ocular care institution, 210 eyes of 210 subjects underwent anterior segment Fourier domain optical coherence tomography (FDOCT). A caliper tool software was used to measure the corneal thickness. For the reproducibility measures, the examination was done by 2 examiners (user 1, user 2) within 30 minutes of each other. For the reliability measure, the retest was done by user 1 on the next day, within 30 minutes of the previous test's time. The total corneal thickness, epithelial thickness, and corneal thickness excluding the epithelium were measured. The mean corneal thickness of the population measured by user 1 was 519.5 ± 31.1 μm, 58.6 ± 4.2 μm, and 460.95 ± 31.4 μm for total cornea, epithelium, and non-epithelial cornea, respectively. The difference in results between user 2 and user 1 was 0.8 ± 7.2 μm, 0.23 ± 3.3 μm, and 0.7 ± 8.2 μm for total, epithelium, and non-epithelial cornea, respectively, and the difference in results between the repeated series by user 1 was 0.49 ± 5.7 μm, -0.13 ± 2.7 μm, 0.61 ± 5.4 μm total, epithelium, and non-epithelial cornea, respectively (paired t-test, P > 0.05). Intraclass correlations ranged from 0.87 to 0.99, coefficients of repeatability from 4.5 to 14.11, and coefficient of variation from 2.3% to 11.1%. Fourier domain anterior segment optical coherence tomography is reproducible and reliable for the measurement of epithelial thickness at vertex.