Application of Near-Infrared Reflectance Spectrometry in the study of atopy. Part I. Investigation of skin spectra

An investigation into the existence of spectral differences and differences in response in terms of water and lipid content between normal and atopic skin is described. Since NIR radiation penetrates complex structured matrices down to a depth of 0.15-0.20 mm, it is evident that the method lends itself to spectral detection of skin components down to the deepest level. First the reproducibility of readings made with the instrument was tested and it was also checked whether the use of the probe caused changes in skin equilibrium due to occlusion. Analysis of the NIR spectra did not enable normal and atopic subjects to be distinguished unequivocally but provided important information on the use of NIR spectrometry in these subjects and insights into the stratum corneum. Although the responses of water and lipid structures could not be read directly from the spectra, it was possible to decompose the global spectral information into components by principal components analysis. It was possible to observe a fraction of variance associated in different ways with water.