Biphasic Change in Retinal Arterial Hemodynamics Amidst Systematic Perfusion Decline With Increasing Degree of Myopia

The purpose of this study was to delineate retinal vessel hemodynamics across myopia severity using high-resolution adaptive optics scanning laser ophthalmoscopy (AOSLO) and investigate their correlation with fundus structure.

In this cross-section study, hemodynamics in intraocular branches of the central retinal artery and vein from 124 participants, including flow velocity, volumetric flow, wall shear stress (WSS), and the wall to lumen ratio (WLR) were derived from AOSLO. Associations of axial length (AL) with these parameters were evaluated, with adjustment for vessel diameter (VD) and other confounders. Partial correlation analysis assessed relationships between hemodynamics and fundus structures, including capillary density and fundus thickness.

Arterial flow velocity and WSS demonstrated a biphasic relationship with longer AL: velocity increased up to 25.13 mm (β = 1.66) and then decreased (β = -2.17), whereas WSS increased up to 24.98 mm (β = 7.53) before declining (β = -17.15). Conversely, venous flow velocity (β = -0.95) and WSS (β = -7.78) progressively declined with increasing AL. After adjustment for confounders, longer AL was associated with increasing WLR in arteries (β = 0.83) and veins (β = 0.58), alongside decreased volumetric flow (artery: β = -0.14 and vein: β = -0.09). Increased WLR showed the strongest correlation with fundus structural changes, including reduced nasal retinal capillary density (ρ = -0.36) and choroid thinning (ρ = -0.44).

This study conducted a detailed assessment of the hemodynamics of retinal vessels at different levels of myopia with AOSLO, revealing severity-dependent alterations characterized by elevated vascular resistance, reduced retinal perfusion, and biphasic arterial response. These hemodynamic alterations were closely correlated with fundus structural changes, suggesting vascular dysregulation may be a contributing factor to the pathophysiological changes associated with increasing severity of myopia.