Computational assessment of blood lipid influence on hemodynamics in human retinal vessels

The study of retinal hemodynamics is pivotal for understanding both physiological and pathological conditions affecting the eye. Microcirculation in the retina exhibits unique rheological properties and flow dynamics compared to larger vessels. This computational study investigates the possible impact of elevated blood lipids on retinal vascular flow characteristics, focusing on viscosity increases and potential blockage effects. We utilized computational fluid dynamics to solve the incompressible Navier-Stokes equations for an image-based retinal vessel network under healthy conditions. Our findings reveal that arterial vessels have a higher average mainstream flow velocity than venous vessels, however, the latter experience higher wall shear stress (WSS) in those fine branch vessels, which are far away from the optical disc. Notably, vessels with more branches in the venous network are subjected to greater WSS. Then, we simulated the effect of elevated blood lipids by increasing venous viscosity by about 10-20%, which led to a proportional rise in WSS. Furthermore, we explored the potential blockage that may caused by elevated blood lipids, leading to localized increases in velocity and WSS. This study provides insights into the hemodynamic alterations induced by hyperlipidemia, highlighting the importance of considering systemic health parameters in ocular disease research and treatment.