Identification of anterior chamber angle parameters with a portable SD-OCT device compared to a non-portable SD-OCT

Abstract

The aim of this study is to compare a portable spectral domain optical coherence tomography (SD-OCT) device with a non-portable SD-OCT for the identification of anterior chamber angle parameters based on location of Schwalbe's line (SL) and to measure their reproducibility. 99 eyes from 46 normal, healthy participants underwent imaging of the inferior iridocorneal angle with the iVue and Cirrus SD-OCT under well-controlled low-light conditions. SL-angle opening distance (SL-AOD) and SL-trabecular iris space area (SL-TISA) were measured by masked, certified graders at the Doheny Image Reading Center using customized Image J grading software. Inter- and intrainstrument, as well as inter- and intraobserver reproducibility of SL-AOD and SL-TISA measurements were evaluated with intraclass correlation coefficients (ICCs) and Bland-Altman plots with limits of agreement. The mean SL-AOD was 0.814 ± 0.315 mm with the iVue and 0.797 ± 0.294 mm with the Cirrus. The mean SL-TISA was 0.247 ± 0.112 mm with iVue and 0.259 ± 0.113 mm with Cirrus. Interinstrument correlation coefficients (r) were 0.93 (P < 0.0001), 0.92 (P < 0.0001), and 0.92 (P < 0.0001) for SL_AOD and SL_TISA, respectively. Intraclass correlation coefficient showing the degree of agreement among SL-AOD and SL-TISA was 0.923 (95 % confidence interval 0.885-0.948) and 0.921 (95 % confidence interval 0.883-0.947) for both devices. The agreement for intrainstrument (ICCs > 0.95), intragrader (ICCs > 0.93), and intergrader (ICCs > 0.96) was excellent. Excellent agreement between the two devices was also documented with Bland-Altman analysis. Both instruments provide consistent and reproducible measurements of anterior chamber angle metrics.

Comparison of iridocorneal angle parameters measured by spectral domain optical coherence tomography and ultrasound biomicroscopy in dogs

“…In addition to intra-observer reproducibility, the interobserver reproducibility of the ICA parameters for SD-OCT was excellent in this study. Previous studies also reported excellent inter-observer reproducibility for AOD and TISA measured using SD-OCT. 3,10,18 In contrast, the inter-observer reproducibility of UBM in our study was good. In previous UBM studies, failure to obtain reproducible ICA and AOD measurements between two examiners has been reported.…”

Investigation of the variability of anterior chamber scan protocol with Cirrus high definition optical coherence tomography

“…Pan et al reported that ICC of AOD from Schwalbe's line for image acquisition by Cirrus was 0.99, and ICCs for inter‐observer and intra‐observer variability for image grading were >0.94. In accordance with the results from the previous studies, we found that ICCs of inter‐observer and intra‐observer variability for image acquisition were >0.98 and for image grading were >0.9 with this new version of Cirrus OCT. Two previous studies have also reported that Cirrus also provided good agreement with other SD‐OCTs such as iVue from Optovue and Spectralis from Heidelberg Engineering in the evaluation of ACAs. Although a low measurement variability has been reported for the previous version of anterior segment imaging of Cirrus OCT, asking the patient to look at an external fixation light located at the side of the machine can likely alter the ACA profile more than if the patient had been in his or her primary gaze position .…”

“…Leung et al and Li et al evaluated ACA measurements by the Visante OCT and reported that inter‐observer and intra‐observer variability in angle measurements was low and ICCs were ≥0.95. In previous studies, low inter‐observer and intra‐observer variability of angle measurement by the previous version of Cirrus OCT have been reported. Pan et al reported that ICC of AOD from Schwalbe's line for image acquisition by Cirrus was 0.99, and ICCs for inter‐observer and intra‐observer variability for image grading were >0.94.…”

Prospective evaluation of optical coherence tomography for disease detection in the Casey mobile eye clinic

“…Prior studies have found high reproducibility of the angle assessment using iVue OCT as well as between different OCT machines. 16 OCT evaluation of the angle could be a useful screening tool because it does not require a skilled ophthalmologist to perform the gonioscopy exam and its non-contact nature improves patient acceptance and comfort. It can be beneficial in populations with a higher prevalence of angle closure where screening for occludable angles and subsequent referral for treatment such as laser peripheral iridotomy could effectively prevent blindness.…”