Cardinal Elements of an Aging Human Eye Model with a Gradient-Index Crystalline Lens

The human eye is an optical system with two components: the cornea and the crystalline lens, with a diaphragm (iris) in contact with the lens. Despite the accommodation process, it is well known that the biometrical data of the human eye changes with age, as does the gradient of the refractive index structure. Therefore, the paraxial properties of the human eye as an optical system evolve with aging. The ABCD matrix formalism has proved to be a good tool to characterize the optical system in the paraxial regime. However, when the optical system has a gradient index element, an ABCD matrix for this element needs to be formulated. Gathering information concerning the aging of the biometric ocular data, a model of the human eye has been created, accurate both anatomically and optically. Together with the ABCD matrix for the GRIN crystalline lens, it is possible to determine the relevant paraxial parameters for the eye model. These parameters—which also vary with the wavelength in the visible part of the electromagnetic spectrum, as the ocular media show light dispersion—help us to study and to teach how the relaxed and emmetropic human eye forms an image on the retina.

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