Repeatability and Reproducibility of Foveal Avascular Zone Area Measurement on Normal Eyes by Different Optical Coherence Tomography Angiography Instruments

Purpose: To compare the foveal avascular zone (FAZ) area measurements produced by different optical coherence tomography angiography (OCTA). Methods: Healthy enrolled volunteers underwent OCTA using 2 different devices: Spectralis HRA+OCTA (Heidelberg Engineering, Heidelberg, Germany) and RS-3000 Advance (Nidek, Gamagori, Japan). Two graders measured FAZ in both superficial (SCP) and deep (DCP) retinal capillary plexuses. The SCP and DCP en face images were visualized automatically segmenting 2 separate slabs defined by the arbitrary segmentation lines created by the software of each OCT device. One grader repeated each measure twice. Results: Fifty-nine eyes were included. The mean FAZ was 0.33 ± 0.09 mm² at the SCP and 0.57 ± 0.17 mm² at the DCP measured with RS-3000 versus 0.30 ± 0.08 and 0.35 ± 0.08 mm², respectively, measured with Spectralis. The measurements of the 2 devices were significantly different (p < 0.0001). The intraoperator agreement was excellent at the SCP (intraclass correlation coefficient, ICC: 0.97 with Spectralis and 0.96 with RS-3000). At the DCP, it was good with Spectralis and fair with RS-3000 (ICC: 0.85 and 0.64, respectively). The interoperator agreement was excellent for Spectralis and good for RS-3000 at the SCP (ICC: 0.97 and 0.93, respectively). It was good at the DCP with both devices (ICC: 0.74 with RS-3000 and 0.81 with Spectralis). Conclusions: FAZ measurements obtained with different OCTA devices differ. These findings should be considered in follow-up studies of patients with retinal vascular diseases.