Development of a Quantitative Method for Evaluation of Skin Radiance and Its Relationship with Skin Surface Topography

Skin radiance is an important determinant of skin beauty that almost all women desire. However, the optical reflection characteristics that create the perception of skin radiance are not fully established. The skin properties associated with radiance have received little attention. The aim of this study is to examine the optical characteristics of skin radiance and its associations with other skin properties. We established a method for evaluating skin radiance by measuring the intensities of specular and diffuse reflection components and investigated their age dependence. The results indicated high levels of both specular and diffusion reflection in radiant skin. An age-dependent decrease and a slight increase of diffuse and specular reflection, respectively, were found in the group aged 60─79 years. We examined the number of ridges and surface roughness of corneocyte cells. High specular reflectance was associated with low numbers of the ridges and surface roughness values of corneocyte cells. Because well-conditioned skin shows high numbers of ridges, smoothing the corneocyte cell surface effectively enhances the specular skin reflection value.