Central Corneal Thickness Measurement in Patients with Glaucoma and Glaucoma Suspects by Spectral-Domain and Swept-Source Optical Coherence Tomography Compared with the Standard Ultrasonic Method.

Purpose: To evaluate the agreement of central corneal thickness (CCT) measurements between spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT) compared with the gold standard ultrasonic corneal pachymetry (US CP). Methods: Adults with glaucoma and glaucoma suspects presenting with typical optic nerve head findings and high intraocular pressure with or without visual field damage were included. Patients underwent anterior segment (AS) SD-OCT (Spectralis, Heidelberg Engineering), AS SS-OCT (DRI-Triton, Topcon), and US CP. For both AS SD-OCT and AS SS-OCT, an 8.3 and a 3.0 mm single horizontal B-scan at the central cornea were performed and manually measured respectively. CCT was measured by three blinded different trained examiners. Intraclass correlation coefficient (ICC) and Bland-Altman plots were used for statistical analysis. Results: Twenty-six eyes from 16 patients with glaucoma and glacuoma suspects were included. The mean (SD) age was 59.1 (10.5) years, and 87% were women. The mean (SD) CCT measurements were 548.04 (33.11) µm for AS SD-OCT, 538.88 (34.84) µm for AS SS-OCT, and 537.12 (29.20) µm for US CP. The overall agreement ICC was 0.915 (95% CI, 0.785-0.964; p<0.001). The best agreement was found between AS SS-OCT and US CP (ICC = 0.929; 95% CI, 0.849-0.967; p<0.001). When comparing AS-OCT methods with US CP, a difference of less than 10 µm was found in 53.8% of the eyes examined by SS-OCT, and in 50% of the eyes examined by SD-OCT. Conclusion: OCT emerges as an effective modality for CCT measurements. This technology provides advantages such as patient comfort, B-scan trackability, and the possibility to conduct multiple glaucoma diagnostic modalities in a single device.