Comparison of the repeatability and reproducibility of corneal thickness mapping using optical coherence tomography according to tear film break-up time.

ABSTRACT

BACKGROUND: To compare the repeatability and reproducibility of corneal and corneal epithelial thickness mapping using anterior segment optical coherence tomography (AS-OCT) according to tear film break-up time (TBUT). METHODS: The included eyes were divided into three subgroups according to TBUT (group 1 TBUT ≤ 5 s, group 2 5 s < TBUT ≤ 10 s, and group 3 TBUT > 10 s). All eyes were imaged separately thrice by two operators to obtain the thickness maps (TMs) of the cornea and corneal epithelium based on spatial zones encompassing a 9-mm-diameter area. Each TM consisted of 25 areas. Intraoperator (repeatability) and interoperator (reproducibility) standard deviations (Sws), coefficients of variation (CoVs), and intraclass correlation coefficients (ICCs) among the tests were calculated and compared in all the areas. RESULTS: Altogether, 132 eyes of 67 subjects were included (50, 47, and 35 eyes in groups 1, 2, and 3; respectively). The ICCs of corneal epithelial thickness and corneal thickness were > 0.75 in most of the areas. Pairwise comparisons showed that AS-OCT exhibited lower repeatability in group 1 than in groups 2 and 3 (P < 0.05). However groups 2 and 3 showed similar results. Sws and CoVs of corneal epithelial thickness exhibited no significant interoperator differences. While no significant differences were observed in corneal thickness in most of the areas. CONCLUSIONS: TBUT significantly influences the repeatability of corneal and corneal epithelial thickness measurements. Poor tear film stability requires careful evaluation of corneal epithelial thickness.