Single point and imaging measurements of the optical clearing process

Abstract

Biomedical optics and photomedicine applications are challenged by the turbid nature of most biological tissue systems. This nature limits the penetration depth of light into the tissue. Optical clearing improves the penetration depth of light by the application of optical clearing agents which produce an equalization of refractive indices between tissue components and causes a decrease in tissue scattering, and thus increase in optical transmittance. In this paper we examine the effects of optical clearing agents on ex vivo porcine skin using the immersion method. We develop a simple model that can be used to compare different aspects of optical clearing agents such as the rate at which the clearing agents enters the tissue and also the reduction in scattering achieved. We examine the change in the reflected light spectrum over time as the clearing agent enters the skin. This is examined via point probe measurements and also a wide field imaging technique with a consumer-end digital camera. The consumer-end digital camera offers a cheap and simple method for analyzing optical clearing agents over a wider field, overcoming the limitations of single point measurements.