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Absorption of the eye lens and macular pigment derived from the reflectance of cone photoreceptors

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Author: Zagers, N.P.A. · Norren, D. van
Type:article
Date:2004
Source:Journal of the Optical Society of America A: Optics and Image Science, and Vision, 12, 21, 2257-2268
Identifier: 238244
doi: doi:10.1364/JOSAA.21.002257
Keywords: Density (optical) · Error analysis · Least squares approximations · Light absorption · Mathematical models · Spectrum analysis · Statistical methods · Cone photoreceptors · Optical Stiles-Crawford effect · Light reflection · biological marker · visual pigment · computer assisted diagnosis · lens capsule · pathophysiology · photoreceptor · pseudophakia · reproducibility · retina cone · retina macula lutea · sensitivity and specificity · spectroscopy · validation study · Aging · Algorithms · Biological Markers · Cones (Retina) · Diagnosis, Computer-Assisted · Lens Capsule, Crystalline · Macula Lutea · Photoreceptors · Pseudophakia · Reproducibility of Results · Retinal Pigments · Sensitivity and Specificity · Spectrum Analysis

Abstract

We measured the amplitude of the directional component of the bleached fundus reflectance, the so-called optical Stiles-Crawford effect, as a function of wavelength. The directional reflectance originates from within the outer segments of the photoreceptors. Thus only two anterior absorbers are of importance: Macular pigment and the crystalline lens. Analysis of spectra obtained in pseudophakes established that the cone photoreceptors act as spectrally neutral reflectors. The reflectance spectra, expressed in density units, resembled the macular pigment density spectrum. Studying age effects in the lens of normal subjects resulted in a description of the optical density of the lens in terms of a "young" and an "aged" template. The young template represents the pigment O-β-glucoside of 3-hydroxykynurenine, which dominates the light absorption in young eyes and decreases with age. The aged template represents the pigments accumulating in the lens with age. The total optical density increased with age, but it was lower in the wavelength region 500-650 nm than was previously assumed on the basis of psychophysical studies. Analysis of the spectra also provided precise individual estimates of the optical density of macular pigment. Finally, we observed a decrease in the photoreceptor reflectivity with age, possibly reflecting a degradation of the photoreceptors. © 2004 Optical Society of America.