Reproducibility and reliability of optical coherence tomography angiography for foveal avascular zone evaluation and measurement in different settings

Purpose:Optical coherence tomography angiography (OCTA) allows delineating the foveal avascular zone (FAZ) easily and noninvasively. The present study aims to test reproducibility and reliability of FAZ evaluation by means of OCTA in different settings. Methods:Twenty-four eyes of 24 normal subjects were investigated using AngioVue OCTA Imaging System. A series of OCTA acquisitions were taken both in basal and in different experimental settings after vasoactive stimuli. Images were evaluated separately by two operators and FAZ area was measured both manually and using the built-in automated measurement tool. Results:No differences for FAZ area were found in the repetition of basal acquisitions, neither in manual nor in automated measurement (0.215 ± 0.06 vs. 0.216 ± 0.07, and 0.268 ± 0.05 vs. 0.264 ± 0.09, first vs. second basal measurement in square millimetres for manual and automated evaluation, P = 0.25 and P = 0.35, respectively). Interoperators correlation was optimal (r2 = 0.978 [95% CI 0.981-0.976]). No differences were found among the other settings, which included first basal and then repeated (second) in the morning, after flickering light stimulus, after a Bruce treadmill stress test, after 30 minutes dark adaptation, and basal in the evening, neither in automated nor in manual measurements. Automated measurements for nonflow areas provided significantly larger diameters than manual ones. Conclusion:AngioVue OCTA Imaging System produces highly reproducible FAZ images with a high interoperators concordance level. Optical coherence tomography angiography capability to detect FAZ area seems not to be influenced by any of the vasoactive stimuli considered in the current study. Nonflow areas seem to be larger when measured automatically than manually.