Reproducibility and agreement of four anterior segment-optical coherence tomography devices for anterior chamber angle measurements

Purpose To compare the reproducibility and agreement of anterior chamber angle (ACA) parameters and metrics obtained by four different anterior segment-optical coherence tomography (AS-OCT) devices. Methods In this prospective study, 30 eyes from 15 normal subjects underwent anterior segment angle scanning using the Spectralis, Cirrus, and Optovue spectral domain optical coherence tomography (SD-OCT), as well as the Visante time-domain optical coherence tomography (TD-OCT). For each eye, the scan line was performed perpendicularly on the inferior (270 degrees) angle, and the inferior ACA image was acquired 2 times. Inter-instrument and intra-instrument, as well as inter-observer and intra-observer reproducibility of anterior chamber angle metrics, Schwalbe's line (SL) to scleral spur (SS) distance (TM-Span), angle opening distance (AOD), and trabecular iris space area (TISA) measurements, were evaluated by intraclass correlation coefficients (ICCs) and Bland-Altman plots with limits of agreement (LoA). Results For this cohort of 30 eyes of 15 normal subjects, the mean TM-Span, AOD, and TISA were 0.966 +/- 0.198 mm, 0.750 +/- 0.205 mm, and 0.286 +/- 0.090 mm(2) from the Spectralis; 0.929 +/- 0.113 mm, 0.717 +/- 0.120 mm, and 0.267 +/- 0.095 mm(2) from the Cirrus; 0.923 +/- 0.191 mm, 0.683 +/- 0.161 mm, and 0.265 +/- 0.072 mm(2) from the Optovue; and 0.970 +/- 0.070 mm, 0.705 +/- 0.150 mm, and 0.279 +/- 0.065 mm(2) from the Visante. The intra-instrument (ICCs > 0.838), intra-grader (ICCs > 0.910), and inter-grader (ICCs > 0.869) agreement were good. Agreement between the four instruments was also good with ICCs from 0.901 to 0.967 for TM-Span, 0.887 to 0.941 for AOD, and 0.923 to 0.961 for TISA. Conclusions Consistent and reproducible ACA measurements could be obtained from multiple AS-OCT devices including both SD- and TD-OCT instruments. These findings have relevance when considering multiple imaging devices in future studies.