Optical clearing of human dura mater

The changes in the optical parameters of the human dura mater in the spectral range 400-700 nm caused by the action of an aqueous solution of mannitol with a concentration of 0.16 g/ml are studied in vitro. The diffusion of mannitol into the tissue leads to a partial matching between the refractive indices of the structure-forming elements (the collagen fibrils) and the base substance of the dura mater (the interstitial fluid). As a result, the light scattering by the biological tissue in the entire spectral range under study is decreased, on the average, by a factor of 1.5-2. The immersion of the biological tissue is shown to cause a decrease in the absorption of the dura mater in the range of the blood absorption bands by a factor of 1.2-1.6. The results presented may prove to be useful in the laser therapy and optical diagnostics of brain diseases. (C) 2005 Pleiades Publishing, Inc.