title: Effect of ocular shape and vascular geometry on retinal hemodynamics: a computational model.
abstract: A computational model for retinal hemodynamics accounting for ocular curvature is presented. The model combines (i) a hierarchical Darcy model for the flow through small arterioles, capillaries and small venules in the retinal tissue, where blood vessels of different size are comprised in different hierarchical levels of a porous medium; and (ii) a one-dimensional network model for the blood flow through retinal arterioles and venules of larger size. The non-planar ocular shape is included by (i) defining the hierarchical Darcy flow model on a two-dimensional curved surface embedded in the three-dimensional space; and (ii) mapping the simplified one-dimensional network model onto the curved surface. The model is solved numerically using a finite element method in which spatial domain and hierarchical levels are discretized separately. For the finite element method, we use an exterior calculus-based implementation which permits an easier treatment of non-planar domains. Numerical solutions are verified against suitably constructed analytical solutions. Numerical experiments are performed to investigate how retinal hemodynamics is influenced by the ocular shape (sphere, oblate spheroid, prolate spheroid and barrel are compared) and vascular architecture (four vascular arcs and a branching vascular tree are compared). The model predictions show that changes in ocular shape induce non-uniform alterations of blood pressure and velocity in the retina. In particular, we found that (i) the temporal region is affected the least by changes in ocular shape, and (ii) the barrel shape departs the most from the hemispherical reference geometry in terms of associated pressure and velocity distributions in the retinal microvasculature. These results support the clinical hypothesis that alterations in ocular shape, such as those occurring in myopic eyes, might be associated with pathological alterations in retinal hemodynamics.
authors.affiliation: Department of Mathematics and Sciences, State University of New York Polytechnic Institute, 100 Seymour Rd, Utica, NY, 13502, USA. dziubea@sunyit.edu.
authors.forename: Andrea
authors.initials: A
authors.lastname: Dziubek
authors.affiliation: Department of Mathematical Sciences, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA.|LABEX IRMIA, Université de Strasbourg, 67000, Strasbourg, France.|Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Guidoboni
authors.affiliation: Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
authors.forename: Alon
authors.initials: A
authors.lastname: Harris
authors.affiliation: Department of Mathematics, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA.
authors.forename: Anil N
authors.initials: AN
authors.lastname: Hirani
authors.affiliation: Department of Mathematics and Sciences, State University of New York Polytechnic Institute, 100 Seymour Rd, Utica, NY, 13502, USA.
authors.forename: Edmond
authors.initials: E
authors.lastname: Rusjan
authors.affiliation: Department of Mathematics and Sciences, State University of New York Polytechnic Institute, 100 Seymour Rd, Utica, NY, 13502, USA.
authors.forename: William
authors.initials: W
authors.lastname: Thistleton
mesh_terms: D003198:Computer Simulation; D004553:Electric Conductivity; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009716:Numerical Analysis, Computer-Assisted; D010539:Permeability; D016062:Porosity; D011312:Pressure; D015203:Reproducibility of Results; D012160:Retina / Q000033:anatomy & histology* / Q000502:physiology*; D012171:Retinal Vessels / Q000033:anatomy & histology* / Q000502:physiology*
keywords: Finite element exterior calculus; Hierarchical porous medium; Mathematical modeling; Ocular curvature; Retinal hemodynamics; Vascular network