A Comparison of Central Corneal Thickness Measurements and Measurement Repeatability Using Three Imaging Modalities

Abstract

Purpose: To compare and analyze central corneal thickness (CCT) measurements and measurement repeatability according to the corneal thickness obtained with anterior segment optical coherence tomography (AS-OCT), ultrasound pachymetry (USP), and dual Scheimpflug imaging (Galilei G4 (R)). Methods: CCT measurements obtained using AS-OCT, USP, and a dual rotating Scheimpflug camera in 120 eyes of 60 healthy subjects were compared and the repeatability was analyzed. Results: The average CCT measurements using AS-OCT, USP, and a dual rotating Scheimpflug camera were 511.23 +/- 37.16, 525.78 +/- 39.22, and 531.43 +/- 41.57 mu m, respectively. The CCT measurement using dual rotating Scheimpflug imaging was statistically significantly thicker than that measured using AS-OCT (p < 0.05). A significant linear correlation was observed among OCT, USP, and dual rotating Scheimpflug measurements (r > 0.900, p < 0.001). All three methods showed high repeatability (intraclass correlation coefficient >= 0.996) for intra-examiner CCT measurements. Conclusions: The CCT measurement results using the three methods were significantly correlated and showed high repeatability. However, the AS-OCT measurement was significantly thinner than that obtained using a dual rotating Scheimpflug camera. CCT measurement with a dual rotating Scheimpflug camera is a better alternative for USP than AS-OCT. Therefore, CCT should be interpreted in the context of the instrument used.