Wide-angle optical model of the eye.

There are two approaches to the design of a wide-angle optical model of the eye. One approach is based upon data on biological and physical characteristics of the eye (cornea, crystalline lens) collected from the literature or from in vivo or in vitro measurements. From these data a model is built whose configuration is as close as possible to that of a living eye. Then the visual function of the model is calculated and checked for its conformity with the living eye. The second design approach starts with measurements of the optical performance of a living eye. Then the unknown parameters (asphericity of the cornea, distribution of the thicknesses of the individual layers of the crystalline lens, their curvatures and refractive indices, and sphericity of the layers) can be calculated by fitting the curve of the corresponding optical performance calculated from the model to the curve measured in vivo. Using this approach, we measured the axial spherical aberrations in 50 emmetropic volunteers (100 eyes), calculated the best fit to all the measurements, and used it as the average curve of axial spherical aberrations of an emmetropic eye. In this paper we present the results and calculations and discuss the validity of this approach.