Skin color independent assessment of aging using skin autofluorescence

M Koetsier,Gerhard Rakhorst,Reindert Graaff,Andries J Smit,Han Chunmao,Thera P Links,Erfan Nur,Helen L Lutgers

doi:10.1364/oe.18.014416

Abstract

Skin autofluorescence (AF) for the non-invasive assessment of the amount of accumulated tissue Advanced Glycation Endproducts (AGEs) increases with aging. In subjects with darker skin colors, measurements typically result in lower AF values than in subjects with fair skin colors, e.g. due to selective absorption by skin compounds. Our aim was to provide a new method for calculating skin AF, yielding values that are independent of skin color. The deviation of skin AF of healthy subjects with various darker skin types (N = 99) compared to reference values from Caucasians showed to be a function of various parameters that were derived from reflectance and emission spectra in the UV and visible range (adjusted R(2) = 80%). Validation of the new algorithm, based on these findings, in a separate dataset (N = 141) showed that results of skin AF can now be obtained to assess skin AGEs independently of skin color.

Highlights

Measuring skin autofluorescence (AF) is a non-invasive method for determining the amount of accumulated tissue Advanced Glycation Endproducts (AGEs)
For assessing correlations between age-corrected skin AF and various parameters that were derived from reflectance spectra in the UV-A and visible range, a subset of 99 subjects (33 subjects from each cohort) was chosen from the total group
The spectrum that is measured directly from the skin during illumination with the UV light source. This spectrum includes a large peak of UV light that is reflected from the skin and a small emission peak, due to autofluorescence of the AGEs and possibly other skin compounds with fluorescence emission in the same wavelenth region, such as NADH and lipofuscins

Summary

Introduction

Measuring skin autofluorescence (AF) is a non-invasive method for determining the amount of accumulated tissue Advanced Glycation Endproducts (AGEs). Skin AF is measured with the AGE Reader, from the mean emission in the 420 – 600 nm range upon UV-A excitation with a peak wavelength of 370 nm. Skin AF measurements in subjects with darker skin colors (UV-reflectance below 10%) typically result in lower values than in subjects with fair skin colors [9]. It is not expected that these subjects have a substantially lower amount of AGEs. The lower AF values are expected to be caused by different absorption of excitation or emission light by skin compounds and scattering effects, especially in the epidermis, and specular reflectance. The observed skin color dependence hinders reliable assessment of skin AGEs in subjects with darker skin color and inhibits the recognition of increased skin AF values

Objectives

Methods

Results

Conclusion