Schematic eye model based on the regression of age-dependent changes of the crystalline lens

Abstract

Purpose: To construct a schematic eye model based on the regression of age-dependent changes of the crystalline lens and determine the effects on retinal image quality of refractive index, transmittance, scattering, and lens shape.

Methods: Optical simulation was performed using the optical design software CodeV. Three-dimensional eye models based on a modified Navarro model eye were used for the simulation. We used a number of published regression models in relation to the shape and optical characteristics of crystalline lens used. Refractive error and modulation transfer function (MTF) were calculated.

Results: With increasing refractive index of the lens nucleus (from 0 to +0.02), refractive errors showed a myopic shift (from 0 to -8.50 D). The amount of change increased in as the lens nucleus became steeper. However, with increasing refractive index of the lens cortex, refractive errors showed a hyperopic shift (from 0 to +2.33 D). As scattering angle increased (from 0 to 30 min arc), MTF decreased overall and the lens nucleus was affected the most. As transmittance at the center of the lens decreased (from 100 to 10%), MTF was increased at 250 c/mm and decreased at 100 c/mm, indicating the effect of apodization.

Conclusions: This schematic eye model based on regression of age-dependent changes of the crystalline lens should prove useful for the comparative evaluation of refractive correction methods and the development of new ophthalmic instruments.

Keywords: 676 refraction • 413 aging • 630 optical properties