Comparison of central corneal thickness with four noncontact devices: An agreement analysis of swept-source technology

Purpose: The purpose of this study was to compare the central corneal thickness (CCT) measurements of four noncontact devices in healthy eyes. Materials and Methods: In a sample of 45 healthy controls, CCT was measured using an optical biometer (IOLMaster 700) based on swept-source optical coherence tomography (SS-OCT), high-resolution rotating Scheimpflug camera system (Pentacam HR), spectral-domain OCT (SD-OCT) device with an anterior segment module (Spectralis), and noncontact pachymetry (NCP) device (Topcon TRK-2P). Agreement among the devices was analyzed using mean differences (i. e., bias) and Bland-Altman analysis with 95% limits of agreement (LoA). Results: Mean CCT measurements were 537.5 +/- 47.5 mu m for SS-OCT optical biometer, 532.3 +/- 43.8 mu m for Scheimpflug system, 521.3 +/- 44.7 mu m for SD-OCT device, and 518.0 +/- 43.1 mu m for NCP (P < 0.001). The SD-OCT device and NCP showed the closest agreement, with a bias of 2.6 mu m (95% LoA, -3.6-8.8 mu m), whereas the SS-OCT optical biometer and NCP showed the least agreement, with a bias of 18.7 mu m (95% LoA, -2.1-39.5 mu m). Bias was 16.1 mu m (95% LoA, -3.1-35.3 mu m) for SS-OCT optical biometer and SD-OCT, 5.1 mu m (95% LoA, -6.8-17.0 mu m) for SS-OCT optical biometer and Scheimpflug system, 10.9 mu m (95% LoA, -15.1-36.9 mu m) for SD-OCT device and Scheimpflug system, and 13.6 mu m (95% LoA, -5-32.2 mu m) for Scheimpflug system and NCP. Conclusions: SS-OCT optical biometer overestimates CCT measurements compared to Scheimpflug system, SD-OCT device, and NCP. Given mean differences and range variations in CCT measurements between devices, SS-OCT optical biometer and Scheimpflug system are interchangeable as are SD-OCT and NCP.