Retinal microvasculature and optic disc alterations in non-pathological high myopia with optical coherence tomography angiography

Purpose This study aims to investigate the early characteristics of retinochoroidal and peripapillary perfusion in non-pathological high myopia (HM) without retinopathy and compare them to the age- and sex-matched healthy subjects using optical coherence tomography angiography (OCTA). Methods This prospective, cross-sectional study included 35 eyes of 35 patients in the non-pathological HM group (axial length (AL) >= 26 mm) and 35 eyes of 35 subjects in the control group. OCT and OCTA were used for the assessment of vessel density, foveal avascular zone, subfoveal choroidal thickness, choriocapillaris flow area, retinal nerve fiber layer thickness, and optic nerve head measurements. Results The VDs of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were significantly reduced in the HM group (47.9 +/- 3.8%; 47.3 +/- 6.6%) compared to the control group (50.8 +/- 2.6%; 54.1 +/- 4.8%) (p < 0.001). The whole vessel density (wpVD) (53.7 +/- 2.7% vs. 56.2 +/- 2.2%) and peripapillary VD (ppVD) (56.4% (range, 45.8-60.4%) vs. 58.4% (range, 52.6-62.3%)) values were significantly lower in the HM group (p < 0.005). The inside disc vessel density (iVD) was similar in both groups (62 +/- 3.3% vs. 61.4 +/- 2.7%) (p = 0.511). Conclusion The vessel densities (VDs) of SCP and DCP, wpVD, and ppVD were lower in the non-pathological HM group, but the iVD value was similar in both groups. This suggests that the main cause of VD reduction is more likely related to globe elongation rather than reduced oxygen and nutrients due to the thinning of the posterior pole (retina, sclera, and choroid). Clinicaltrials.gov registration ID NCT04631991, 11/11/2020