Noninvasive estimation of chronological and photoinduced skin damage using Raman spectroscopy and principal component analysis.

ABSTRACT

BACKGROUND: Skin aging can be attributed to endogenous and exogenous factors which modify the hydration and protein structure of the skin which can be measured using Raman spectroscopy. METHOD: This study included 21 healthy adult volunteers, aged 32-81 years, Raman spectra were obtained from sun-protected and sun-exposed skin, also three millimeter punch biopsies of sun-exposed skin were collected and analyzed. The Raman spectra were analyzed using principal component analysis and the results were correlated with clinical and histological findings. RESULTS: The principal component analysis of the Raman spectra shows that the first principal component (PC1) obtained from the sun-protected skin is related to the age of the subject, which can be taken as a measure of chronological aging, the second (PC2) and fourth (PC4) principal components obtained from Raman spectra of sun-exposed skin are related to the amount of solar elastosis and collagen, respectively. CONCLUSION: In this work a relationship was found between histological properties of photoaged skin and noninvasive measurements based on Raman and principal components analysis (PCA). These relationships can be used to assess noninvasively the photoinduced damage and chronological characteristics of skin.