FDTD analysis of the light propagation in the cones of the human retina: an approach to the Stiles–Crawford effect of the first kind

Abstract

In this work, we analyse the propagation of light in the human retinal cones by the finite-difference time-domain method (FDTD) in cylindrical coordinates, for systems with axial symmetry or body of revolution (BOR). This work constitutes a preliminary approach to the study of the Stiles?Crawford effect of the first kind (SCE I), as a cone has been simulated, while the SCE I is a consequence of a large number of photoreceptors. The FDTD method enables a numerical resolution of Maxwell's equations. With the computational implementation of these equations we have obtained, in the cone endface, the intensity patterns for different angles with which the light strikes the input side of the photoreceptor, and different wavelengths of incident light. In view of the results, the characteristics of fibre optics presented by the retinal cones remain valid, as does the goodness of the method and of the computational cone model that we have proposed. This work demonstrates, in short, the computational validity of our cone model as well as the power and versatility of the FDTD-BOR algorithm for the analysis and comprehension of the phenomenon of light propagation in retinal photoreceptors. It therefore offers broad possibilities in the field of research on visual processes, serving as support for analysis and interpretation of experimental measurements.