Objective. To compare fourier-domain optical coherence tomography (FD-OCT) and time-domain OCT (TD-OCT) in the determination of thinnest corneal thickness (TCT). Methods. This study included 55 keratoconus patients and 50 healthy volunteers. The RTVue-OCT (FD-OCT) and Visante-OCT (TD-OCT) were used for the measurement of the TCT. Three consecutive scans were performed. The comparison and agreement between the two modalities were analyzed by paired t-test, the Pearson correlation, intraclass correlation coefficient (ICC), and Bland-Altman plots. intraobserver repeatability was analyzed by the intraobserver within-subject standard deviation (S (w)), coefficient of variation (CV (w)), and ICC. Results. The TCT value of normal corneas was higher by RTVue-OCT (530.4 ± 19.7 μm) than Visante-OCT (521.5 ± 18.3 μm) (p < 0.001). For keratoconus eyes, the TCT was 425.0 ± 58.2 μm and 424.4 ± 55.7 μm (difference being 0.6 ± 10.2 μm, p = 0.604). Strong correlation (r = 0.938∼0.985) (ICC = 0.915-0.984) was observed between the two OCTs, and each OCT exhibited excellent repeatability in determining the TCT in all subjects (ICC = 0.984-0.994). Conclusions. The values of TCT obtained from RTVue-OCT and Visante-OCT were highly correlated; however, the two values were different. Both OCT instruments exhibited good intraobserver reliability. The existence of systematic differences suggested that the two instruments cannot be used interchangeably.
Wang, C., Xia, X., Tian, B., & Zhou, S. (2015). Comparison of Fourier-Domain and Time-Domain Optical Coherence Tomography in the Measurement of Thinnest Corneal Thickness in Keratoconus. Journal of Ophthalmology, 2015. https://doi.org/10.1155/2015/402925