Measurement of optical properties of human skin in the ultraviolet wavelength range: age-related changes

Abstract

In recent years, ultraviolet (UV) light therapy has been attracting attention as a treatment method for skin diseases such as atopic dermatitis, vitiligo, and psoriasis which have been considered difficult to treat. However, regarding the research on treatment, clinical studies have been the main research focus without much in-depth consideration into the radiative properties of UV light within the skin. Therefore, it is essential to know the optical properties, scattering and absorption coefficients, of the skin in the UV wavelength range to improve the treatment strategy. Our group has been developing a non-invasive method, reflection spatial profile method (RSPM), for measuring optical properties of skin and elucidated optical property differences arising out of cancer drugs [1] . In this study, we have developed a novel system that operates in the range of UV wavelengths irradiating the skin with a structured incoherent source and detecting the reflected light with a CCD camera. Measurements are being conducted with human subjects of different age groups. Based on results obtained from the forearm and hand measurements of 76 subjects consisting of 31 males and 45 females in their 20s~30s. UV light penetration depth can be estimated from the optical properties obtained. It was found that the amount of light absorption can vary up to 1.5 times at the same depth depending on gender, age, and site.