Study Objective: The retina is one of the most metabolically active tissue with highest oxygen consumption per weight. An intricate and multi-layered (i.e. plexus) network of capillary blood vessels nourish the retinal cells while minimally interfering with transmitted light. Different plexus nourish different layers of nerve cells and photoreceptors. During retinal diseases, such as diabetic retinopathy and age-related macular degeneration, different plexus are known to be affected differently. Yet, how the microcirculatory blood flow and hemodynamics differs in different capillary plexus remains unknown. The objective is to use a high-fidelity computational modeling study to predict how blood cell flow and capillary hemodynamics varies across different retinal plexus.Hypothesis: Microcirculatory blood flow and hemodynamics differ among different retinal vascular plexus which eventually leads to varying degree of vasculopathy in retinal diseases.Methodology: A high-fidelity 3D computational model is used to predict blood cell flow and capillary hemodynamics in three vascular plexus, namely, superficial (SVP), intermediate (ICP) and deep (DCP) plexus, of the macula of the human retina. The model is first principle-based fluid/structure interaction model and accurately resolves flow and deformation of each red blood cell (RBC) and vascular geometry and topology of as obtained from in vivo images. Each tissue area simulated are ~500X500 μm2 and contains more than a hundred vessels with diameter from 5--30 μm. The model accurately predicts diverse hemodynamic parameters in 3D space and time, such as RBC velocity and distribution, pressure and wall shear stress (WSS) in every vessel with submicron resolution.Data and Summary Results: Model predictions are used to compare hemodynamics in three vascular plexuses. The mean blood velocity is predicted to be highest in SVP and lowest in DCP. This happens due to longer path the RBCs need to take to reach DCP. Also, several vessels in DCP have very low flow rate: these vessels are located relatively far from the supplying arterioles diving from ICP. Quite surprisingly, the DCP vessels also found to have higher hematocrit. Additionally, higher WSS is predicted in SVP, while blood viscosity is predicted to be higher in DCP.Conclusions: Significant differences are predicted in RBC distribution, WSS, and blood velocity among three vascular plexus in the human retina. These differences tend to explain why retinal vasculopathy manifests differently across three plexus. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Krishnan et al. (Fri,) studied this question.