Reproducibility and repeatability of foveal avascular zone measurements in healthy subjects by optical coherence tomography angiography

Abstract

Background/aims: To assess the reproducibility and repeatability of foveal avascular zone (FAZ) area measurements using optical coherence tomography angiography (OCT-A) in healthy subjects.

Methods: Sixty healthy volunteers (60 eyes) were subjected to FAZ area measurements by means of high speed and high resolution spectral-domain OCT (SD-OCT) XR Avanti with the split-spectrum amplitude decorrelation angiography algorithm by two experienced examiners in two different sessions.

Results: The mean±SD age of the subjects was 28.9±7.6 years. Overall FAZ areas measured by the first and second observer were 0.251±0.096 mm(2) and 0.252±0.096 mm(2), respectively. Within subjects, the coefficients of variations were 1.83% (95% CI 1.51% to 2.20%) and 1.86% (95% CI 1.33% to 2.43%) for the first and second observers, respectively. The coefficient of repeatability average measurements of FAZ area were 0.015 mm(2) and 0.013 mm(2) for the first and second observers, respectively. The intraclass correlation coefficient values were 0.997 (95% CI 0.995 to 0.998) and 0.998 (95% CI 0.996 to 0.999) for the first and second observers, respectively. Inter- and intraobserver concordance correlation coefficients ranged from 0.994 (95% CI 0.990 to 0.977) to 0.999 (95% CI 0.997 to 0.999) and from 0.997 (95% CI 0.995 to 0.998) to 0.996 (95% CI 0.994 to 0.998), respectively.

Conclusions: FAZ area measurements by means of OCT-A showed excellent reproducibility and repeatability in healthy eyes. OCT-A is a non-invasive diagnostic method, and its reliability makes it an interesting potential diagnostic tool for disease detection and follow-up in retinal pathologies involving foveal microcirculation.

Keywords: Anatomy; Angiogenesis; Macula; Retina.