Study of optical clearing of blood by immersion method

Light scattering in blood caused by refractive index mismatch between erythrocyte cytoplasm and blood plasma leads to a reduction in imaging spatial resolution, imaging depth and contrast of optical imaging techniques. A possible solution to this problem is of the addition of biocompatible clearing agents, such as glucose, fructose, glycerol, dextrans etc. The basic principle of the optical clearing technique is refractive index matching between erythrocyte cytoplasm and blood plasma. Optical clearing, a technique that has been successfully demonstrated with biologic tissue, represents a promising approach to increasing the imaging depth for various techniques, for example optical coherence tomography (OCT). OCT is based on low-coherence interferometry to produce cross-sectional tomographic imaging of the internal microstructure in materials and biological tissues by measuring the echo time delay and magnitude of backscattered light. One of the main advantages of this technique is the ability to investigate turbid and highly scattering media, such as whole blood. To determine the optimal concentration of clearing agents required for blood optical clearing in order to improve light penetration depth for optical coherence tomography, clearing agents such as glucose and fructose, with various concentrations were added to blood and investigated by OCT. Changes in light attenuation and sedimentation and aggregation properties of blood depending on particular agent and its concentration were studied.