Asian Journal of Physics Vol. 15, No. 1 (2006) 1-14 In vivo investigation of human skin optical clearing and blood microcirculation under the action of glucose solution Alexey N Bashkatov 1 , Alexander N Korolevich 2,3 , Valery V Tuchin 1 , Yuri P Sinichkin 1 , Elina A Genina 1 , Mikhail M. Stolnitz 1 , Nataly S Dubina 4 , Sergey I Vecherinski 4 , Michael S Belsley 2 1 Institute of Optics and Biophotonics, Department of Optics and Biomedical Physics of Saratov State University, Saratov, Russia 2 Physical Department, Minho University, Campus Gualtar, 4709 Braga, Portugal 3 B I Stepanov Institute of Physics of National Academy of Sciences of Belarus, Skarina Ave., 68, 220072 Minsk, Belarus 4 GP ”MTZ Medservice”, 220009 Minsk, Belarus We present experimental results on optical properties of the human skin controlled by administration of the 40%- glucose solution. In vivo reflectance spectra of the human skin were measured. Results of the experimental study of influence of the 40%-glucose solution on reflectance spectra of the human skin are presented. A significant decrease of reflectance of the human skin under action of the osmotic agent is demonstrated. The experiments show that administration of the glucose solution allows for effective control of tissue optical characteristics, that makes skin more transparent, thereby increasing the ability of light penetration through the tissue. Laser Doppler flowmetry has been used for study of skin blood microcirculation under the action of the glucose solution. Results of the experiments demonstrated that at the action of the glucose solution blood perfusion and blood concentration increase, however the mean blood velocity does not change. The presented results can be used in developing functional imaging techniques, including OCT and reflectance spectroscopy. A potential benefit of the optical clearing technique is the improvement of laser therapeutic techniques that rely on sufficient light penetration to a target embedded in tissue. © Anita Publication. All rights reserved. 1 Introduction Recent technological advancements in the photonics industry have led to a resurgence of interest in optical imaging technologies and real progress toward the development of non-invasive clinical functional imaging systems. Over the last decade, non-invasive or minimally invasive spectroscopy and imaging techniques have witnessed widespread exciting applications in biomedical diagnostics, for example, optical coherence tomography (OCT) [1,2], visible and near-infrared elastic-scattering spectroscopy [3,4], fluorescent [1,3,5] and polarisation spectroscopy [6,7]. Spectroscopic techniques are capable of deep-imaging of tissues that could provide information of blood oxygenation [8] and detect cutaneous, brain and breast tumours [9], whereas confocal microscopy [10], OCT [2,11-13], and multi- photon excitation imaging [10,14] have been used to show cellular and sub-cellular details of superficial living tissues. Spectroscopic and OCT techniques are applicable for blood glucose monitoring with diabetic patients [15-17]. Besides diagnostic applications optical methods are widely used in modern medicine, for example, for photodynamic therapy [18-20], and for laser surgery of different diseases [21,22]. Interest in using optical methods for physiological-condition monitoring and cancer diagnostics and therapies has been increased due to their simplicity, safety, low cost, contrast and resolution features in contrast to conventional X-ray computed tomography and ultrasound imaging [9]. The main limitations of the majority of the imaging techniques, including OCT and near-infrared (NIR) spectroscopy deal with the strong light scattering in superficial tissues [9,23-26], which cause decrease of spatial resolution, low contrast, and small penetration depth. Solution of the problem, i.e. reducing of light scattering, and thus improving of image quality and precision of spectroscopic information, can be connected with control of tissue optical properties.