Abstract
This study was conducted to investigate the size and shape of the foveal avascular zone (FAZ) determined by optical coherence tomography angiography (OCTA) and the relationship of the size and shape to the clinical findings in normal subjects. This was a cross-sectional study with seventy eyes of 70 volunteers. The size of the superficial FAZs were assessed by its area, length of perimeter, and Feret’s diameter, and the shape by the circularity, axial ratio, roundness, and solidity. The correlations between each parameter and the clinical findings were statistically determined. The coefficients of variation (CV) of the parameters of FAZ size were higher than that of the parameters of FAZ shape. The refractive error and axial length were significantly correlated with area-related factors. The central macular thickness (CMT) was significantly correlated with all parameters. Although the CMT was a critical factor that was significantly correlated with the size and shape characteristics of the FAZ, the shape might be a better factor for characterizing the FAZ than the size because of the low CV of shape-related factors and the characteristics are less affected by the other ocular factors.
Highlights
Fluorescein angiography (FA) and indocyanine green angiography (ICGA) have been important methods to evaluate retinal diseases[1,2,3]
The size of the foveal avascular zone (FAZ) determined by FA was less than 40% of that determined by Optical coherence tomography angiography (OCTA) which limits the usefulness of FA in determining the size of the FAZ9
The area of the FAZ detected by OCTA could be an indicator of retinal disorders such as diabetic retinopathy and retinal vascular occlusion[10,11,12,13,14,15,16,17]
Summary
Fluorescein angiography (FA) and indocyanine green angiography (ICGA) have been important methods to evaluate retinal diseases[1,2,3]. Optical coherence tomography angiography (OCTA) is a newly developed method that is noninvasive and does not require the intravenous injection of contrast dyes It is based on motion contrast imaging of high-resolution volumetric blood flow that can generate en face angiographic images of the capillary plexuses in the different layers of the retina and choroid in seconds[6]. The area of the FAZ detected by OCTA could be an indicator of retinal disorders such as diabetic retinopathy and retinal vascular occlusion[10,11,12,13,14,15,16,17] It is unclear whether the size of the FAZ is the single best indicator of the presence of retinal pathology or the effectiveness of a treatment protocol because it has relatively large variability[18,19,20,21,22]. The circularity and axial ratio of the FAZ in eyes with diabetic retinopathy were significantly different www.nature.com/scientificreports/
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