Macular Microvasculature in High Myopia without Pathologic Changes: An Optical Coherence Tomography Angiography Study

PURPOSE: To investigate macular microvasculature changes using optical coherence tomography angiography (OCTA) and analyze their correlation with the structural parameters in highly myopic eyes. METHODS: We measured the area of the foveal avascular zone (FAZ) and the parafoveal vessel density in the superficial and deep retinal plexuses using OCTA. The magnification effect of the FAZ area was corrected using Bennett's formula. Retinal thickness measured at each corresponding area of the OCTA parameters, subfoveal choroidal thickness, and ocular characteristics were reviewed, and the relationships between the microvasculature measurements and the ocular structural characteristics were explored. RESULTS: Fifty-two eyes with high myopia and 52 normal sex- and age-matched controls were included in the analysis. The FAZ area was significantly larger in the myopic eyes (p = 0.023). The superficial parafoveal vascular density was significantly decreased (p = 0.007) in the myopic eyes compared with the normal eyes, whereas there was no significant difference in the deep parafoveal vascular density (p = 0.226). Regarding the retinal thickness, only the parafoveal inner retinal thickness was significantly smaller in the myopic eyes than in the normal eyes (p = 0.023). The FAZ and subfoveal choroidal thickness were significantly correlated with the axial length, and the parafoveal inner retinal thickness was significantly correlated with the superficial parafoveal vascular density (all p < 0.05). CONCLUSIONS: The FAZ was enlarged and the parafoveal vascular density was reduced in the highly myopic eyes. The decrease was prominent in the superficial capillary plexuses and well-correlated with the retinal thickness profiles. The macular microvascular network alteration may be attributed to the ocular axial elongation that occurs with myopia.