Mechanisms of optical clearing in cellular tissue

The mechanisms of optical clearing in cellular tissue in response to application of a hyperosmotic solute were theoretically considered using the Rayleigh-Gans approximation to scattering. The effect on scattering coefficient due to changes of three input parameters including refractive index ratio, scatterer size, and scatterer volume fraction were investigated. Decreasing refractive index ratio has the greatest effect on decreasing tissue scattering coefficient, and this parameter is likely to undergo a large variation. Decreasing scatterer size can result in a slight increase or decrease in tissue scattering coefficient depending on initial scatterer size, percent decrease in radius, and wavelength. The effect of tissue scattering coefficient due to an increase in the volume fraction of scatterers depends on initial scatterer volume fraction and percent change. Scattering always decreases when initial scatterer volume fraction is greater than .5. Results of simulations illustrate the high sensitivity of changes in tissue scattering due to the initial and final states of these parameters. Improved understanding of the mechanisms of tissue clearing will require accurate experimental measurement of these input parameters.

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