Repeatability, reproducibility, and agreement regarding measurement of choroidal vascularity index between OCT and OCT angiography

To explore the repeatability, reproducibility, and agreement in the measurement of the choroidal vascularity index (CVI) for different swept-source optical coherence tomography (OCT) devices and between OCT and OCT angiography (OCTA) images.

Two swept-source OCT imaging systems, VG200I and Topcon DRI OCT Triton, were used to capture OCT and OCTA images in triplicate. The first and third images were taken by one operator, and the second image was taken by another operator. The built-in software was used to calculate the CVI from the OCTA images (CVI-OCTA), and a custom-designed algorithm was used to calculate the CVI from the OCT images (CVI-OCT). Repeatability and reproducibility were assessed with the intraclass correlation coefficient (ICC), and agreement between devices and between OCT and OCTA were evaluated with Bland-Altman analysis.

Sixty-eight eyes from 35 adults (17 females) were included in the analysis. The average age of the participants was 23.6±2.3y, with an average spherical equivalent refraction of -3.08±2.47 D and an average AL of 25.21±1.20 mm. Both OCT devices demonstrated high repeatability and reproducibility in measuring the CVI-OCTA (all ICCs>0.894 across five choroidal regions) and CVI-OCT (all ICCs>0.838). Furthermore, the between-device agreement in measuring the CVI-OCT was good [mean difference (MD) ranging from -2.32% to -3.07%], but that in measuring the CVI-OCTA was poor (MD, 1.48% to -7.43%). Additionally, the between-imaging agreement (CVI-OCTA versus CVI-OCT) was poor for both devices (Triton, MD, 6.05% to 12.68%; VG200I, MD, 6.67% to 12.09%).

Both OCT devices and the two analytical methods demonstrate good stability. The inter-device consistency of CVI-OCT is good, while the inter-device consistency of CVI-OCTA and the consistency between the two analytical methods in the same device are both poor.