The interaction of light with the human eye is a complex phenomenon that involves both visual and non-visual pathways. In this study, we employ the Finite-Difference Time-Domain (FDTD) method to numerically simulate how electromagnetic waves propagate through heterogeneous ocular tissues. Specifically, the objective is to compare how two different wavelengths (380, 450 and 750 nm) behave as they traverse the eye's anatomical structure, which includes a lens with a gradient refractive index (GRIN). The simulations reveal wavelength-dependent focal behavior, where shorter wavelengths exhibit sharper focusing and pronounced diffraction, while longer wavelengths show broader intensity profiles and deeper focal regions. These results are essential for understanding chromatic aberrations, optimizing optical devices for retinal imaging, and improving the design of intraocular lenses (IOLs). The proposed model, validated with anatomical parameters, enables a more accurate representation of electromagnetic wave interactions within the eye than traditional ray-based or paraxial approximations.