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To assess the effectiveness of plasmonic photothermal therapy (PPT) multiple intravenous strategy of gold nanorods (GNRs) administration was used before laser exposure. The model of alveolar liver cancer PC-1 was used in male outbred albino rats, which were intravenously administrated by single and multiple injections of GNRs and then were treated by PPT. The gold dosage was 400 μg (single injection group), 800 μg (double injection group), 1200 μg (triple injection group), and absorption maximum of gold nanorods suspension was at the wavelength of 808 nm. 24 hours after last injection the tumors were irradiated by the 808-nm diode laser during 15 min at power density 2.3 W/cm2. Temperature control of the tumor heating was provided by IR imager. 24 hours after the PPT the half of animals from each group was withdrawn from the experiments and the sampling tumor tissue for morphological study was performed. In survived animals the growth of tumors was evaluated during 21 days after the PPT. The antitumor effects of PPT after triple intravenous injection were comparable with those obtained at direct intratumoral administration of similar total dose of GNRs. The effectiveness of PPT depended on gold accumulation in tumor, probably, due to sufficient vascularizTation of tumor tissue.

Durability of bonded interfaces between dentin and a polymer material in resin-based composite restorations remains a clinical dentistry challenge. In the present study the evolution of bonded interfaces in biological active environment is estimated in vivo. A novel in vivo method of visual diagnostics that involves digital processing of color images of composite restorations and allows the evaluation of adhesive interface quality over time, has been developed and tested on a group of volunteers. However, the application of the method is limited to the analysis of superficial adhesive interfaces. Low-coherent optical computer tomography (OCT) has been tested as a powerful non-invasive tool for in vivo, in situ clinical diagnostics of adhesive interfaces over time. In the long-term perspective adhesive interface monitoring using standard methods of clinical diagnostics along with colour image analysis and OCT could make it possible to objectivise and prognosticate the clinical longevity of composite resin-based restorations with adhesive interfaces.

We are proposing a new method for enhancement of optical imaging of proximal interphalangeal (PIP) joints in humans at skin using optical clearing technique. A set of illuminating laser diodes with the wavelengths 670, 820, and 904 nm were used as a light source. The laser diodes, monochromatic digital CCD camera and specific software allowed for detection of the finger joint image in a transillumination mode. The experiments were carried out in vivo with human fingers. Dehydrated glycerol and hand cream with urea (5%) were used as optical clearing agents (OCAs). The contrast of the obtained images was analyzed to determine the effect of the OCA. It was found that glycerol application to the human skin during 60 min caused the decrease of contrast in 1.4 folds for 670 nm and the increase of contrast in 1.5 and 1.7 folds for 820 nm and 904 nm, respectively. At the same time, the hand cream application to the human skin during 60 min caused the decrease of contrast in 1.1 folds for 670 nm and the increase of contrast in 1.3 and 1.1 folds for 820 nm and 904 nm, respectively. The results have shown that glycerol and the hand cream with 5% urea allow for obtaining of more distinct image of finger joint in the NIR. Obtained data can be used for development of optical diagnostic methods of rheumatoid arthritis.

The wide application of optical methods in the areas of diagnostics, therapy and surgery of modern medicine has stimulated the investigation of optical properties of various biological tissues. Numerous investigations related to determination of tissue optical properties are available; however, the optical properties of many tissues have not been studied in a wide wavelength range. In this work the optical properties of parietal peritoneum in the wavelength range 350-2500 nm were measured. Measurement of the diffuse reflectance, total and collimated transmittance were performed using LAMBDA 950 (Perkin Elmer, USA) spectrophotometer with an integrating sphere, and values of absorption and scattering coefficients, and the scattering anisotropy factor were calculated by inverse Monte Carlo Method.

We are proposing a new method for enhancement of optical clearing agent delivery into the skin using fractional laser microablation of the skin surface. The Palomar Lux2940 erbium laser with the wavelength 2940 nm and pulse duration of 5 ms was used as a light source. Two regimes of laser action were used in the experiments: the first one realized microablation of skin upper layer and the second one created microchannels in skin. As optical clearing agents mineral oil and PEG-300 were used. In vivo studies were carried out with white outbred rats. Both parameters: the permeability coefficient of the agents in the tissue and the optical probing depth were measured using the OCT system at a wavelength of 930 nm. The following values of the permeability coefficient of the skin with microablation were obtained: (3.41±0.46)×10 -5 cm/s and (2.35±0.30)×10 -5 cm/s for mineral oil and PEG-300, respectively, at the use of the surface microablation and (3.32±0.09)×10 -5 cm/s and (3.61±0.34)×10 -5 cm/s for mineral oil and PEG-300, respectively, at the use of the microporation. The results have shown that the joint application of mineral oil with microablation in the first regime promotes maximal (nearly 2-folds) increasing of optical probing depth in 30 min. Obtained data can be used for development of optical diagnostic methods of skin diseases.

In this paper we have studied effect of a hyperosmotic optical clearing agent (OCA), such as polyethylene glycol, on the fluorescence intensity from a target located in subcutaneous area in the model experiments. As a fluorescence agent the nanocomposite including gold nanorods with hematophorphyrin was used. The remitted fluorescent signal traveling to the tissue surface was monitored over time as the tissue was treated with the OCA. The detected fluorescent signal increased as the scattering in tissue samples was substantially reduced. The study has shown how OCA can be used to improve the detected signal at localization of subcutaneous target tissue at the photothermal or photodynamic therapy. Immersion clearing of skin can be also useful for improvement of laser exposure efficiency due to the increasing of light penetration depth.

Measurements of optical properties of fingernail and underlying tissues using OCT are presented. Review and measurements of Raman spectra of tissue and phantom compounds were done. Updating of modeling algorithm for scattering coefficient calculation on the basis of integrating sphere measurements accounting for particle size-distribution was also done. The adequate fingernail and underlying tissue optical model at 830 nm was evaluation. Tissue phantoms potentially suitable for calibration of Raman instrumentation for glucose sensing were designed and tested on the basis of epoxy resin, TiO2-nanoparticles and micron-sized silica particles with the capillary net-work.

Result of Monte Carlo simulations of skin optical clearing is presented. The model calculations were carried out with the aim of studying of spectral response of skin under immersion liquids action and calculation of enhancement of light penetration depth. In summary, we have shown that: 1) application of glucose, propylene glycol and glycerol produced significant decrease of light scattering in different skin layers; 2) maximal clearing effect will be obtained in case of optical clearing of skin dermis, however, absorbed light fraction in skin dermis changed insignificantly, independently on clearing agent and place it administration; 3) in contrast to it, the light absorbed fraction in skin adipose layer increased significantly in case of optical clearing of skin dermis. It is very important because it can be used for development of optical methods of obesity treatment; 4) optical clearing of superficial skin layers can be used for decreasing of power of light radiation used for treatment of acne vulgaris.

The study is aimed at evaluation of diagnostic potential of plasmon-resonant nanoparticles as contrast agents for various techniques based on backward diffuse light scattering from biotissues. We consider the theoretical spectra of diffuse backscattering from a plane layer of gold nanospheres embedded into a plane layer of scattering dielectric spheres that mimic a strongly scattering sample of a biotissue. It is shown that the backscattering spectra contain information about 35-nm gold spheres provided the location depth is less than 600 mkm. The simulated color characteristics resemble the measured characteristics of a rat skin. The measured diffuse reflection spectra of 35-nm gold colloid are close to the spectra of 70/15-nm silica/gold nanoshells although the plasmon resonance wavelengths (520 and 630 nm) differ significantly.

Investigation of skin water loss and clearing agent delivery through stratum corneum is presented. Effectiveness of the method "lattice of islets of damage" for enhancement of stratum corneum permeability for water and 71% glycerol solution providing the skin clearing was investigated. Dehydration induced by both stimuli evaporation and osmotic agent action was studied by weight measurements. Measurements of refractive index dynamics of glycerol and water during its interaction with skin samples were carried out. The results have shown that proposed method allows effective transepidermal water loss and delivery of optical clearing agents.

We present experimental results of investigation of the optical properties of the human eye sclera controlled by administration of osmotically active chemical, such as 40%-glucose solution. Administration of the chemical agent induces diffusion of matter and as a result equalization of the refractive indices of collagen and ground material. Results of the experimental study of influence of the glucose solution on the absorption and scattering properties of human sclera are presented. In vitro reflectance and transmittance spectra of the human sclera samples were measured by commercially available spectrophotometer CARY-2415 in the spectral range from 400 to 1800 nm. The reduced scattering coefficient of human sclera samples is significantly decreased under action of the osmotical solution were demonstrated.

The optical properties of human stomach wall mucosa were measured in the wavelength range 400-2000 nm. The measurements were carried out using the commercially available spectrophotometer CARY-2415 with an integrating sphere. The combined method includes inverse adding-doubling method and inverse Monte Carlo method was used to determine the absorption and scattering coefficients and anisotropy factor from the measurements.

Spectral measurements of sclera reflectance during its interaction with aqueous solutions of both Cortexin and Retinalamin have been carried out. Twenty three samples includ ed in the study were human sclera and rabbit sclera in vitro . The results of the experiments have shown that penetration of Cortexin as well as Retinalamin into sclera tissue leads to the decrease of sclera reflection due to optical immersion. Estimation of diffusion coefficients of studied solutions was made on the basis of analys is of reflectance change dynamics of the sclera samples. Diff usion coefficients of Cortexin and Retinalamin in sclera tissue were estimated as 4.4 2.7 10ru 6 and 1.82 0.14 10ru 6 cm 2 /sec, respectively. Obtained values of diffusion coefficient allowed estimating time needed for total penetr ation of both agents through scleral membrane at subtenon's injection of studied agents. The results are important for treatment of partial optic atrophy observed at primary open-a ngle glaucoma and others eye diseases.

Based on the presented two-layer eye iris model, the iris diffuse reflectance has been calculated by Monte Carlo technique in the spectral range 400-800 nm. The diffuse reflectance spectra have been recalculated in L*a*b* color coordinate system. Obtained results demonstrated that the iris color coordinates (hue and chroma) can be used for estimation of melanin content in the range of small melanin concentrations, i.e. for estimation of melanin content in blue and green eyes.

Absorption properties of Indocyanine Green (ICG) dissolved in both water and 40%-ethanol for potential using in laser selective thermolysis have been researched. Correlation between magnitudes and positions of absorption bands of ICG in dependence on the kind of solvent and concentration of ICG has been studied. Interaction between ICG solutions and rat skin in vitro has been investigated. Shift of the main absorption peaks of ICG solutions in skin has been defined. Such shift is caused by ICG interaction with protein molecules of the stratum corneum and dermis. Diffusion coefficients of ICG in skin have been estimated at diffusion of aqueous solutions through dermis and at diffusion of alcohol solutions through both dermis and epidermis as (7.70±2.51)×10 -7 , (18.79±3.35)×10 -7 and (6.85±3.75)×10 -7 , respectively.

The mathematical model of clearing agent diffusion after intradermal injection has been developed. Skin was presented as multilayer medium, but one layer with proper boundary conditions is considered. Analytical solution of the boundary problem for small and large time intervals is obtained. 1 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, which causes decrease of spatial resolution, low contrast, and small penetration depth. Solution of the problem, i.e. reducing light scattering, and thus improving image quality and precision of spectroscopic information, can be connected with control of tissue optical properties. The tissue scattering properties can be significantly changed due to action of osmotically active immersion liquids, for example, glucose. The aqueous glucose solutions were used for optical clearing of skin, sclera, dura mater, etc. 2

We present experimental results on optical properties of cranial bone controlled by administration of propylene glycol and glycerol. Both transmittance and reflectance spectra of human and porcine cranial bone in vitro were measured. Measurements of total transmittance and diffuse reflectance have been performed using a spectrophotometer with an integrating sphere. The reflectance measurements have been carried out with an optical multichannel spectrometer with a fiber-optical probe. For estimation of absorption and reduced scattering coefficients of the bone the inverse adding-doubling method was used. The decrease of reflectance and increase of transmittance of the samples under action of the immersion agents was demonstrated. The experiments have shown that administration of the immersion liquids allows for effective control of tissue optical characteristics, that makes bone more transparent, thereby increasing the ability of light penetration through the tissue. The presented results can be used in developing functional imaging techniques, including OCT and reflectance spectroscopy.

The optical properties of human cranial bones were measured in the wavelength range 800-2000 nm. The measurements were carried out using the commercially available spectrophotometer with an integrating sphere. The inverse adding-doubling method was used to determine the absorption and reduced scattering coefficients from the measurements.

Based on the experimental data obtained in vivo from digital analysis of color images of human irises, the mean melanin content in human eye irises has been estimated. For registration of the color images a digital camera Olympus C-5060 has been used. The images have been obtained from irises of healthy volunteers as well as from irises of patients with open-angle glaucoma. The computer program has been developed for digital analysis of the images. The result has been useful for development of novel and optimization of already existing methods of non-invasive glaucoma diagnostics.

We present experimental results on optical properties of the human skin controlled by administration ofthe 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.

The clinical results of photodynamic therapy of maxillary sinusitis have been presented. 0.1%-Methylene Blue aqueous solution in combination with He-Ne laser irradiation (632.8 nm) has been used for treatment of patients with acute and chronic maxillary sinusitis. Efficacy of the photodynamic therapy was estimated with the use of the following criteria: the state of respiration, olfaction, duration of purulent discharge, reconstruction of transport function of ciliary epithelium, etc. The obtained results have shown that the photodynamic therapy is effective in comparison with conservative methods of treatment of the diseases.

Based on the experimental data obtained in vivo from digital analysis of color images of human irises, the mean melanin content in human eye irises has been estimated. For registration of the color images a digital camera Olympus C-5060 has been used. The images have been obtained from irises of healthy volunteers as well as from irises of patients with open-angle glaucoma. The computer program has been developed for digital analysis of the images. The result has been useful for development of novel and optimization of already existing methods of non-invasive glaucoma diagnostics.

The optical properties of human maxillary sinus mucosa were measured in the wavelength range 400-2000 nm. The measurements were carried out using the commercially available spectrophotometer with the integrating sphere. The inverse adding-doubling method has been used to determine the absorption and reduced scattering coefficients from the measurements. Diffusion of Methylene Blue in the mucous tissue has been studied in vitro and value of the diffusion coefficient of Methylene Blue in the tissue has been estimated at 20°C as (4.77±2.9)x10-7 cm2/sec.

to 1200 nm6. One of the main problem of the use of optical methods in medicine deals withhigh scattering and absorption of light by different tissue chromophores, like hemoglobin. Optical properties of blood inthe above mentioned spectral range are mainly determined by the hemoglobin content. Thus, the possibility of in vivocontrol of blood optical properties significantly increases the efficiency of existing methods of optical tissue diagnosticin visible and NIR spectral range.The optical properties control implies the change of the scattering or absorption properties of optically turbid media,including tissues and blood. Optical immersion is a rather effective method to decrease the scattering. This method is

The study of Methylene Blue penetration in both skin and subcutaneous fat is presented. Experiments have been carried out with both rat skin and human adipose tissue in vitro at room temperature. Microscopic analysis with digital imaging system has been applied for visualizing and investigation of the Methylene Blue diffusion in the epidermal, dermal and adipose tissue. Diffusion coefficient of Methylene Blue in skin in vitro has been estimated.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The near-infrared (NIR) laser radiation due to its high penetration depth is widely used in phototherapy. In application to skin appendages a high selectivity of laser treatment is needed to prevent light action on surrounding tissues. Indocyanine Green (ICG) dye may provide a high selectivity of treatment due to effective ICG uploading by a target and its narrow band of considerable absorption just at the wavelength of the NIR diode laser. The goal of this study is to demonstrate the efficacy of the NIR diode laser phototherapy in combination with topical application of ICG suggested for soft and thermal treatment of acne vulgaris. 28 volunteers with facile or back-located acne were enrolled. Skin sites of subjects were stained by ICG and irradiated by NIR laser-diode light (803 or 809 nm). Untreated, only stained and only light irradiated skin areas served as controls. For soft acne treatment, the low-intensity (803 nm, 10 - 50 mW/cm2, 5-10 min) or the medium-intensity (809 nm, 150 - 190 mW/cm2, 15 min) protocols were used. The single and multiple (up to 8-9) treatments were provided. The individual acne lesions were photothermally treated at 18 W/cm2 (803 nm, 0.5 sec) without skin surface cooling or at 200 W/cm2 (809 nm, 0.5 sec) with cooling. The results of the observations during 1-2 months after the completion of the treatment have shown that only in the case of the multiple-wise treatment a combined action of ICG and NIR irradiation reduces inflammation and improves skin state during a month without any side effects. At high power densities (up to 200 W/cm2) ICG stained acne inflammatory elements were destructed for light exposures of 0.5 sec. Based on the concept that hair follicle, especially sebaceous gland, can be intensively and selectively stained by ICG due to dye diffusion through pilosebaceous canal and its fast uptake by living microorganisms, by vital keratinocytes of epithelium of the canal and sebaceous duct, and by rapidly proliferating sebocytes, new technologies of soft and thermal acne lesions treatment that could be used in clinical treatment of acne were proposed.

SUMMARY Control oftissue optical properties is important for development ofoptical tomography, photodynamic therapyand selective photodamage of tissue components. As a scattering medium, tissue shows optical effects that arecharacteristic for turbid optical systems. Administration of the appropriate chemical agents, like solutions of glucose,glycerol,propylene glycol, etc. can effectively change scattering properties of a living tissue.1Control of skin optical properties was related to the immersion of refractive indices of scatterers and groundmatter. Skin optical properties in general are defined by dermis because of relatively big thickness of dermis (95% ofthe human skin). The dermis consists mainly of network of collagen fibers, elastic fibers, and an interstitial substanceconsisting of proteoglycans, salts, and water. Refractive indices of skin components differ from that of interstitialmaterial. The variation in refractive index causes light scattering that decreases light penetration into a tissue.Osmotic active agents (glucose, dimethyl sulfoxide, trasograph, verografin, glycerol, propilene glycol, etc.)have refractive indices higher than interstitial matter and can be used to reduce the scattering in tissues. Tissue —

Water is the most important biological liquid. On the basis of literature data we present a simple approximation of water refractive index in dependence on temperature and wavelength in the spectral range from 200 to 1000 nm. The approximation is important for different applications in biomedical optics and optics of tissues.

This practical work enables students: to obtain knowledge ofprinciple ofdigital analysis ofcolor image of biologicalobjects; to study technique for measurement of transmittance and reflectance of biological objects using their digitalimages; to study inverse Monte Carlo method for estimation oftissue optical properties; to estimate optical properties ofhuman hair by inverse Monte Carlo method and spatial digital image analysis.Digital imaging is a method whereby images are represented by a series ofnurnbers. Each number usually represents ameasure of energy reflected from a tiny elemental portion of the structure that is being imaged. In two-dimensional

We present experimental results on study of Methylene Blue penetration into skin using a method of digital analysis of color images. Experiments were carried out with a rat skin in vitro. Dependence of the penetration depth of Methylene Blue on dyeing time ofthe tissue was researched. Diffusion coefficients of Methylene Blue within the skin in vitro were estimated.

We have presented experimental data on in vivo and in vitro study on the optical clearing of the scleral tissue controlled by administration of the osmotic liquids. For example, administration of glucose induces matter diffusion and as a result equalization of the refractive indices of scleral tissue scatterers and interstitial fluid. The significant increase of transmittance and decrease of reflectance of the sclera under glucose solution action have been demonstrated. The glucose diffusion coefficient has been estimated. The results of in vitro study of polarization features of scleral optical transmittance at tissue clearing are also presented.

We present experimental results on optical properties of the rat skin controlled by administration of osmotic chemical, such as glycerol. Administration of glycerol induces matter diffusion and as a result equalization of the refractive indices of skin scatterers and interstitial fluid. The significant increase of the skin sample transmittance under action of glycerol has been demonstrated. The mean value of the glycerol diffusion coefficient has been estimated as(formula available in paper).© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A special training laboratory on optical biophysics for the undergraduate and postgraduate students specialized in biophysics, biochemical physics and medical physics in the framework of sub-specialties on biomedical optics, laser medicine, information technologies and mathematical modeling in medicine, and biomedical transducers and sensors is described. The laboratory consists of several sets of topically united practical works: (1) Electronics; (2) Coherent optics of scattering media and interferometry of random phase objects; (3) Coherent-domain optical methods in bio-medicine; (4) In vivo reflectance and fluorescence spectroscopy of human skin; (5) Educational-research setups for postgraduate students; (6) Tissue optics and spectroscopy.

Experimental results on in vivo and in vitro immersion clearing dynamics of the skin under action of the osmotic agent are presented. The significant decrease of the human skin reflectance in vivo under action of glucose solution is demonstrated. In vitro experiments with dyed immersion agents have shown that the immersion mostly penetrates into skin tissue though the dermal layer. Diffusion of the immersion agent through the stratum corneum barrier was insignificant. It was shown the hypodermic injection of the immersion agent is an effective way for the agent administration. The time-dependent contrast of the blood perfused areas in the cleared skin was estimated. The diffusion coefficient of 40%-glucose solution in skin in vivo was estimated as D equals (2.56+/- 0.13)(DOT)10-6cm2sec.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Theoretical and in vitro and in vivo experimental study of spectral and polarization characteristics of the human and rabbit eye tissues are presented. The possibility of control of optical properties of eye comea, lens and sciera is discussed and realized experimentally for glucose solution as the refractive index matching factor.

Monitoring of laser energy absorbed inside tissue is very impotent for laser thermocoagulation of tumors, laser surgery etc. Experimental results have shown that analysis of optoacoustic signal magnitude induced by short laser pulse inside tissue can give quantitative information about laser fluence absorbed by the tissue. We have investigated some tissue phantoms with absorbing objects inside. The first harmonic (1064 nm) of Q-switched Nd:YAG-laser was used for generation of optoacoustic signals.

The double-wavelength laser scanning microphotometer (DWLSM) with high spatial resolution had been developed for in vitro measuring of hair shaft and follicle absorbance. The instrument allows for determining the absorbance distribution across and along hair shaft and follicle. The instrument is based on standard universal binocular microscope. The construction of the instrument and the data processing reduces the influence of the light scattering on the hair and tissue samples.

We presented RGB video microscopic system for in vitro monitoring of optical properties of hair shaft and follicle and experimental results of study of the hair optical and geometrical properties using RGB analysis techniques.

Results of development of spectrophotometric technique for human hair testing in the laboratory and clinical conditions are presented. Hair tester, which can be used for measurements of optical parameters of in vitro hair samples at three fixed wavelengths of illuminating light, is described. Usage of CCD sensor as photodetector allows one to provide spatial-resolved analysis of the hair optical properties and to measure geometric parameters of the hair sample. Experimental results obtained with designed instrumentation and technique are presented.

We present experimental results on optical properties of the rat skin controlled by administration of osmotically active chemical, such as the 40%-glucose solution. In vivo reflectance and in vitro transmittance spectra of the rat skin were measured. Result of the experimental study of influence of the 40%-glucose solution on reflectance and transmittance spectra of the rat skin are presented. The significant increase of transmittance and decrease of reflectance of the rat skin under action of osmotical agent are demonstrated. The average value of glucose solution diffusion coefficient was estimated as

Experimental study and computer modeling of light propagation in a turbid media with different content of scattering particles were done. Latex phantoms as a model of living tissue have been investigated. Experimental results have shown saturation of transmittance and reflectance at selected wavelengths with concentration. These saturation effects are explained by changes of packing factor of scatterers and should be included in description of living tissue optical property changes due to homeostasis.

We present experimental results and computer modeling on the optical properties of the human scleral tissue. The wavelength dependence of the refractive index of collagen fibers in the human scleral tissue was estimated on the base of Mie theory. Dispersion formula describing this dependence was derived. The results are general and can be used to describe optical properties of many other fibrous tissues.

We present experimental results and computer modeling of investigation on the optical properties of the human dura mater controlled by administration of osmotically active chemical, such as mannitol and glucose solutions with various concentrations. Administration of chemical agent induces diffusion of matter and as a result equalization of the refractive indices of collagen and ground material. Results of experimental study of influence of osmotical liquids (mannitol and glucose solutions) on reflectance and transmittance spectra of the human dura mater are presented. The significant decreasing of the reflectance and increasing of the transmittance of the human dura mater samples under action of osmotical solutions were demonstrated.