Simulation of cellular changes on Optical Coherence Tomography of human retina

Abstract

We present a methodology to assess cell level alterations on the human retina responsible for functional changes observable in the Optical Coherence Tomography data in healthy ageing and in disease conditions, in the absence of structural alterations. The methodology is based in a 3D multilayer Monte Carlo computational model of the human retina. The optical properties of each layer are obtained by solving the Maxwell's equations for 3D domains representative of small regions of those layers, using a Discontinuous Galerkin Finite Element Method (DG-FEM). Here we present the DG-FEM Maxwell 3D model and its validation against Mie's theory for spherical scatterers. We also present an application of our methodology to the assessment of cell level alterations responsible for the OCT data in Diabetic Macular Edema. It was possible to identify which alterations are responsible for the changes observed in the OCT scans of the diseased groups.

Convergence of an explicit iterative leap-frog discontinuous Galerkin method for time-domain Maxwell’s equations in anisotropic materials

“…Moreover we developed a 2D model which simulates the light scattering by a single nucleus in the outer nuclear layer of the retina. This work was elaborated in the framework of a more general project with a real application (see [3,14]).…”

“…This work is part of a research project which aims to develop a cellular model of the human retina able to simulate different retinal/cellular conditions and how these changes are translated to an Optical Coherence Tomography scan [14]. Simulating the full complexity of the retina, in particular the variation of the size and shape of each structure, distance between them and the respective refractive indexes, requires a rigorous approach that can be achieved by solving Maxwell's equations.…”

“…This work was developed in the framework of a more general project that aims to develop a computational model to simulate the electromagnetic wave's propagation through the eye's structures in order to create a virtual optical coherence tomography scan [14].…”

Quantifying scattering coefficient for multiple scattering effect by combining optical coherence tomography with finite-difference time-domain simulation method

“…4 Different models of OCT have been established to obtain the optical properties of samples with further consideration of multiple scattering effect. 5,6 Among these works, Thrane et al were the first to propose the use of modulated interferometer signals of an OCT system, which can be expressed analytically based on the extended Huygens-Fresnel (EHF) principle, and to further consider the effect of multiple scattering. 7 In addition, EHF theory has commonly been utilized to numerically quantify optical properties from A-scan signals of OCT images.…”

Stability of a Leap-Frog Discontinuous Galerkin Method for Time-Domain Maxwell's Equations in Anisotropic Materials

“…[3,11,18]), most of the formulation of the DGTD methods present in the literature are restricted to isotropic materials ( [8,9,13]). Motivated by our application of interest described in [2,16], in the present paper we consider a model with an heterogeneous anisotropic permittivity tensor. The treatment of anisotropic materials within a DGTD framework was discussed for instance in [6] (with central fluxes) and in [10] (with upwind fluxes).…”