A multi-domain model for microcirculation in optic nerve: Blood flow and oxygen transport

Abstract

Microcirculation of blood and transport of oxygen play important roles in the biological function of the optic nerve and its diseases. This work develops a multi-domain model for the optic nerve, that includes important biological structures and various physical mechanisms in blood flow and oxygen delivery. The two vascular networks are treated as five domains in the same geometric region, with various exchanges among them (such as Darcy’s law for fluid flow) and with the tissue domain (such as water leak, diffusion). The numerical results of the coupled model for a uniform case of vasculature distribution show mechanisms and scales consistent with literature and intuition. The effects of various important model parameters (relevant to pathological conditions) are investigated to provide insights into the possible implications. The vasculature distribution (resting volume fractions here) has significant impacts on the blood circulation and could lead to insufficient blood supply in certain local regions and thereby affect the delivery of oxygen. The water leak across the capillary wall will have nontrivial effects after the leak coefficients pass a threshold. The pulsatile arterial pressure leads to expected pulsatile patterns and stable spatial profiles, and the uniform case is almost the averaged version of pulsatile case. The effects of viscosity, the stiffness of blood vessel wall, oxygen demand, etc. have also been analyzed. The framework can be extended to include ionic transport or to study the retina when more biological structural information is available.