Analysis of the robustness of the lens GRIN profile in a schematic model eye

In this work, an improvement of a previously-published human eye model with aging is presented. The previous eye model showed the overestimated performance of an averaged MTF at low spatial frequencies at all ages. Since that model had rotationally symmetrical corneal surfaces, these have been modeled to resemble an astigmatic element according to the recent experimental published data and have been included to produce a more accurate eye model. The gradient refractive index (GRIN) profile proposed for the crystalline lens has not been modified to test its robustness. Further, a tilt and decentration of the lens, and only a decentration for the iris, have been permitted in order to fit the average performance of the new eye model with aging. The results demonstrate that the GRIN profile for the crystalline lens fits the model well, since the decentration and/or tilt of the lens and the iris are sufficient free parameters to simulate the performance of the retinal image quality of an emmetropic human eye with aging, having an average astigmatic cornea.