FOVEAL AVASCULAR ZONE VOLUME

Purpose: To propose a new clinical evaluation index, foveal avascular zone (FAZ) volume, and analyze its statistical significance. Methods: A semiautomatic method is proposed to measure the FAZ volume in optical coherence tomography angiography images as follows: The region of interest was flattened and annotated axially. The labeled pixels in the restored region of interest were counted as the FAZ volume. Linear regression and the independent samples t -test were performed for the statistical analysis. Results: Sixty-one normal, 64 high myopia, and 42 diabetic retinopathy eyes were imaged using optical coherence tomography angiography. For normal eyes, the FAZ volume correlates inversely with central macular thickness (superficial: P = 0.004; deep: P < 0.001) and positively with area ( P < 0.001). For high myopia eyes, the deep plexus FAZ ( P = 0.34) and total FAZ ( P = 0.38) volumes show no significant difference, whereas the superficial plexus FAZ volume is significantly larger than control ( P < 0.001). For diabetic retinopathy eyes, the superficial plexus FAZ ( P = 0.001), deep plexus FAZ ( P = 0.014), and total volumes ( P = 0.002) are significantly larger than control. Conclusion: The FAZ volume is proposed for depicting the 3D structure of the FAZ. It shows greater sensitivity for vascular alteration that makes it meaningful for clinical analysis.