Clinical features of microvasculature in subzones of parapapillary atrophy in myopic eyes: an OCT-angiography study

Purpose To investigate the microvasculature in subzones of parapapillary atrophy (PPA) and their associated factors in healthy myopic eyes using optical coherence tomography (OCT) angiography. Methods The cross-sectional study included 55 healthy myopic eyes with PPA. The superficial radial peripapillary capillary (RPC) and choroidal microvascular densities were delineated and measured in alpha, beta, and gamma zone PPA using OCT angiography, respectively. The structural parameters including the width and area in each subzone and corresponding retinal nerve fiber layer thickness were further measured. Statistical analysis was performed to explore the relationship between the vascular and structural parameters. Results The mean age and mean axial length of the participants were 27.55 ± 5.72 years and 25.19 ± 1.08 mm. Among alpha, beta, and gamma zone PPA, the beta zone showed the lowest RPC density, which was negatively correlated with the area and width of beta zone ( P < 0.05). The gamma zone showed the highest RPC density, which was positively correlated with the retinal nerve fiber layer thickness of gamma zone ( P < 0.01). Compared with alpha zone, both gamma and beta zones showed marked decrease of choriocapillaris. The beta zone showed a lower choroidal microvascular density than that of gamma zone ( P < 0.01). Choroidal microvascular density in beta and gamma zones were negatively correlated with the width of beta zone and gamma zone, respectively ( P < 0.01). Conclusions Topographic differences on superficial RPC and choroidal microvasculature were found among the subzones of PPA. A microcirculatory deficiency in beta zone PPA may exist in myopic eyes.