Abstract
Purpose::
To provide a model for the spectral density of the aging ocular media.
Methods::
We analyzed the nearly complete literature on the spectral absorption of the human eye media at all available ages. The data were divided in donor material, psychophysics, and reflectometry. Five templates were defined to provide an adequate description of the spectra from 300-700 nm. All templates had a Gaussian shape, except one that describes light scatter.
Results::
Two templates were needed in all media (lens, cornea, aqueous, and vitreous). They stand for Rayleigh scatter and the absorbance of tryptophan (max = 273nm). Three additional templates for the lens represent absorbance in kynurenine derivatives like 3-hydroxy kynurenine glucoside (max = 370 nm), and absorbance in two substances found at older age (both with max = 325 nm). Aging trend functions for all templates except tryptophan were obtained separately for donor material, psychophysics, and reflectometry. All functions showed a linear slope on an age squared scale. No aging was found in the cornea, aqueous, and vitreous.
Conclusions::
The aging functions based on donor material are the most reliable given the extensive data base. With the model the spectral density of any part of the human ocular media can now be calculated at any age for all wavelengths between 300-700 nm.
Keywords: aging • crystallins • optical properties