Assessment of retinochoroidal microvasculature in young Chinese Han and Uyghur adults with mild-moderate myopia: An OCTA study

Objective To compare the differences in retinochoroidal microvasculature between Han and Uyghur population with mild-moderate myopia using optical coherence tomography angiography (OCTA) . Method This prospective and cross-sectional study included 60 young Chinese Han and Uyghur subjects.They are divided into two groups according to their ethnics (Han group and Uyghur group). All subjects underwent ophthalmic screening examinations. Retinal and choroidal parameters were evaluated using swept-source OCTA (SS-OCTA), including retinal and choroidal thickness, vessel flow density (VFD), foveal avascular zone (FAZ) area, choroidal vascularity volume and index (CVV and CVI) and vascular length density (VLD). Results Han and Uyghur subjects had mean ages of 24.93 ± 1.70 and 25.57 ± 1.36, respectively ( p =  0.116). No significant differences were found in retinal parameters, including thickness, VFD and FAZ area between the two groups. Compared with Han population, the Uyghurs were found to have thicker choroidal thickness ( P  = 0.004), higher CVV ( P  = 0.002) and CVI ( P  = 0.003). Axial length (AL) was negatively associated with VFD-SCP, VFD-DCP, VFD-whole retina and VFD-choriocapillaris layer in Uyghur subjects based on univariate linear regression analysis. However, only VFD-choriocapillaris layer was negatively associated with AL after correction for age and gender using multifactor linear regression analysis. For the Han subjects, no retinal and choroidal parameters was found to be associated with age, gender and AL in both univariate and multifactor linear regression analysis. Conclusion Young Uyghurs with mild-moderate myopia have significantly thicker choroidal thickness, higher CVV and CVI compared to matched Han subjects, which may partially elucidate the etiological mechanisms underlying the reduced myopia prevalence observed within Uyghur cohort.