Reproducibility and differences in area of foveal avascular zone measured by three different optical coherence...

This study was performed to compare the area of the foveal avascular zone (FAZ-area) obtained by three optical coherence tomography angiography (OCTA) instruments. This was a cross-sectional, non-interventional study of twenty-seven healthy right eyes. The superficial and deep FAZ-area was measured manually with three OCTA instruments: Triton (Topcon), RS3000 (Nidek), and CIRRUS (Zeiss). The intra-rater, inter-rater, and inter-instrument correlation coefficients (CC) were assessed. The intra-rater and inter-rater CC were significantly high for the superficial and deep FAZ-areas (P < 0.001). The inter-instrument CC (95% confidence interval) for the superficial FAZ-area was 0.920 (0.803-0.965) for Triton vs RS3000, 0.899 (0.575-0.965) for RS3000 vs CIRRUS, and was 0.963 (0.913-0.983) for CIRRUS vs Triton (P < 0.001). For the deep FAZ-area, the inter-instrument CC was 0.813 (0.633-0.910) for Triton vs RS3000, 0.694 (0.369-0.857) for RS3000 vs CIRRUS, and 0.679 (0.153-0.872) for CIRRUS vs Triton (P < 0.001). The superficial FAZ-area (mm²) was 0.264 ± 0.071 with Triton, 0.278 ± 0.072 with RS3000 and 0.257 ± 0.066 with CIRRUS. For deep FAZ-area, it was 0.617 ± 0.175 with Triton, 0.646 ± 0.178 with RS3000 and 0.719 ± 0.175 with CIRRUS. The FAZ-area from these instruments was clinically interchangeable. However, the absolute values of FAZ-area are significantly different among them. These differences must be considered in comparing the FAZ-areas from different OCTA instruments.