Central corneal thickness measurements with Fourier-domain optical coherence tomography versus ultrasonic pachymetry and rotating Scheimpflug camera.

PURPOSE: To compare the accuracy and repeatability of Fourier-domain optical coherence tomography (FD-OCT) with ultrasonic pachymetry (USP) and a rotating Scheimpflug camera for measuring the central corneal thickness (CCT).
METHODS: The CCT was measured in 30 subjects (30 normal corneas) by the same examiner using RTVue-100 FD-OCT with an anterior segment adaptor, Pentacam rotating Scheimpflug camera, and SP-2000 USP. Two examiners obtained one FD-OCT measurement from 10 eyes of 5 subjects to assess interexaminer reproducibility.
RESULTS: The mean CCT (±SD) measured by FD-OCT, USP, and the Pentacam were 530 ± 33, 544 ± 34, and 552 ± 35 μm, respectively. Significant correlations were found between FD-OCT and USP (r = 0.97; P < 0.0001), FD-OCT and Pentacam (r = 0.97; P < 0.0001), and USP and Pentacam (r = 0.96; P < 0.0001). Pairwise comparisons showed that the FD-OCT CCT measurement was significantly thinner than those of the other 2 methods (P < 0.001 for all comparisons). Regarding intraexaminer repeatability, the intraclass correlation coefficients ranged between 0.97 and 0.98. There was high repeatability of the CCT measurements with all methods. FD-OCT also had high interexaminer reproducibility (intraclass correlation coefficient = 0.98).
CONCLUSIONS: RTVue-100 FD-OCT may be a useful alternative for measuring the CCT; however, it significantly underestimates the CCT compared with the USP and the Pentacam with slight differences. Although highly correlated, the measurements are not directly interchangeable in clinical practice.