Acircularity and Circularity Indexes of the Foveal Avascular Zone in High Myopia

We explored the association between foveal avascular zone (FAZ) parameters and high myopia using optical coherence tomography angiography (OCTA). To evaluate the specific influence of high myopia on the FAZ, we divided 106 eyes of 106 patients into quartiles based on the axial length. The upper quartile was then defined as the high myopia group (n = 27), while the lower quartile was the non-high myopia group (n = 26). The FAZ parameters of these two groups were then retrospectively compared to investigate variations in FAZ size and morphology. The mean axial length and spherical equivalent were 23.96 ± 0.94 mm and -2.27 ± 1.58 diopters in the non-high myopia group and 27.42 ± 0.36 mm and -8.12 ± 2.14 diopters in the high myopia group, respectively. The areas of superficial and deep FAZ, perimeters of deep FAZ, major axis lengths of deep FAZ, minor axis lengths of superficial and deep FAZ were significantly larger in eyes with high myopia than in eyes with non-high myopia ( P < 0.05). Linear regression analyses showed that no significant correlation was observed between FAZ areas and acircularity and circularity index of FAZ in non-high myopia group, conversely, FAZ areas strongly correlated with acircularity and circularity index of FAZ in high myopia group. We found that An increase in the FAZ area in highly myopic eyes was accompanied by a significant variation in FAZ acircularity and circularity indexes. Further research should address whether these findings are associated with future disease development in highly myopic eyes.