Optical coherence tomography angiography analysis of the foveal avascular zone: evaluation and measurement of reproducibility and reliability in different settings.

Abstract

Purpose : The foveal avascular zone (FAZ) can be easily and non-invasively analyzed by means of optical coherence tomography angiography (OCTA). The main goal of present study is to assess reproducibility and reliability of FAZ evaluation by means of OCTA in different settings.

Methods : Twenty-four eyes of 24 normal subjects were investigated by using AngioVue OCTA Imaging System. Both basal and experimental settings following vasoactive stimuli OCTA acquisitions were taken. Images were evaluated separately by two operators and built-in automated tool were used to measure FAZ area.

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). Inter-operators correlation was optimal (r²=0.978 [95% CI 0.981 to 0.976]). No differences were found among other settings, which included first basal and then repeated (second) in the morning, after flickering light stimulus, after Bruce treadmill stress test, after 30 minutes dark adaptation, and basal in the evening, neither in automated nor in manual measurements. Non-flow areas were found significantly larger using automated measurements if compared to the manual ones.

Conclusions : AngioVue OCTA Imaging System allows to obtain highly reproducible FAZ images with a high inter-operators concordance level. OCTA capability to detect FAZ area seems not to be influenced by any of the vasoactive stimuli considered in the current study. Moreover, automated measurement revealed larger non-flow areas than manual one.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.