Assessment of inter-device agreement in quantifying choriocapillaris flow deficits in normal eyes

Abstract

Purpose : To compare choriocapillaris flow deficits (CCFD%) obtained from three different optical coherence tomography angiography (OCTA) devices in healthy subjects

Methods : Twenty-six healthy eyes of 26 subjects were included in this retrospective institutional review board (IRB) approved study. Fovea-centered OCTA scans (6 x mm) were obtained by three devices: Heidelberg Spectralis spectral domain (SD) OCT using a full spectrum probabilistic approach (FSBA) algorithm (888 x 888 pixels), Zeiss Cirrus 5000 AngioPlex (SDOCT) using the optical microangiography (OMAG) algorithm (1024 x 1024 pixels) and Zeiss Plex Elite 9000 swept source (SS) OCT using the OMAG algorithm (1024 x 1024 pixels). For CC assessment, the CC slab was positioned 4 – 20 µm from Bruch’s membrane for the Angioplex and Plex Elite, and for the Spectralis the default CC slab 10 – 30 µm from Bruch’s membrane (as segmented by the Spectralis) was used. CC slabs were binarized using Image J (Figure 1) and the CCFD% was measured using the Phansalkar radius of ~ 20 µm, adjusted for each device based on the size and resolution of the images. Repeated measures analysis of variance (ANOVA) with Tuckey’s post hoc test and Pearson correlation were used to compare the measurements.

Results : The mean age of the subjects was 47.6 ±13 years and 43% were females. The CCFD% measured by the devices varied significantly from each other (p < 0.01). The mean CCFD% measured by the Spectralis was the highest at 57% (± 13.21%), followed by the Angioplex at 25.7% (± 9%), and the Plex Elite at 7.62 (± 3.06%). There was a significant positive correlation between CCFD% measured by SS-OCTA and SD-OCTA devices (Angioplex and Plex Elite) using the OMAG algorithm (r = 0.78, p = 0). Of note, this correlation was better than the correlation between two SD-OCTA devices using different algorithms FSBA and OMAG (r = 0.389, p = 0.04) (Figure 2). The pairwise comparison showed a significant difference in the mean CCFD% between each device.

Conclusions : The correlation between swept source and spectral domain OCT devices using the same OCTA algorithm is better than between SD-OCT devices using different algorithms. However, the CC flow deficit values differ significantly across all devices and a simple conversion factor does not appear possible to interrelate results. These findings have implications for the use of multiple OCTA devices in clinical research studies.

This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.