Open AccessAn innovative method to measure skin pigmentation
Author(s) -
Masuda Yuji,
Yamashita Toyonobu,
Hirao Tetsuji,
Takahashi Motoji
Publication year - 2009
Publication title -
skin research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.521
H-Index - 69
eISSN - 1600-0846
pISSN - 0909-752X
DOI - 10.1111/j.1600-0846.2009.00359.x
Subject(s) - melanin , human skin , irradiation , absorption (acoustics) , ultraviolet , dermatology , hemoglobin , biomedical engineering , chemistry , attenuation coefficient , materials science , optics , medicine , biology , biochemistry , physics , optoelectronics , genetics , nuclear physics , composite material
Background/purpose: It is crucial to establish an accurate method for measuring skin pigmentation in cosmetic science and clinical dermatology. Here, we report a non‐invasive precise method for measuring skin melanin content. Methods: In order to determine the concentrations of melanin and hemoglobin in skin, we used the spectrum resolution (SR) method. In brief, the absorption spectrum of the skin was calculated from the reflection spectrum using a spectrophotometer. The concentrations of melanin and hemoglobin were then determined using a multiple regression analysis, assuming that the absorption spectrum of the skin is expressed as a linear summation of the absorptions of melanin and hemoglobin according to the Lambert–Beer law. The skin changes in the volar forearm, which had been irradiated by ultraviolet rays (UV), were observed daily by the SR method. Results: A multiple regression analysis with an absorption spectrum of 500–700 nm was performed. The multiple correlation coefficient was 0.993, resulting in a satisfactory precise estimate of the concentrations of melanin. After UV irradiation, the concentration of melanin monitored by the SR method increased until 8 days and decreased gradually afterwards. Conclusions: The SR method allows the evaluation of the changes of epidermal melanin induced by UV irradiation.