Modeling of the corneal layer of the rabbit's eye using Mueller matrix analysis

Abstract

The aim of this project was to theoretically model the propagation of polarized light through the corneal layer of the anterior chamber of the rabbit's eye as a Mueller matrix and to verify the model experimentally. The results will be utilized for the research conducted towards the development of a noninvasive in vivo blood glucose sensor using optical polarimetric methods. The sensitivity and performance of the noninvasive glucose sensor is greatly affected by the birefringence of the corneal layer of the eye, which varies due to the random motion of the eye induced by the respiratory and cardiac processes. Corneal birefringence changes the polarization-state of the input light as it passes through the anterior chamber of the eye. Several parameters that could possibly influence the state of polarization include the birefringence of the cornea at the point of incidence of input light, the thickness of the cornea, the orientation of the fast axis of the cornea at the point of incidence, and the wavelength of light used. The cornea was effectively modeled as a linear retarder to take into account these parameters. The optical system designed and built for the verification of the theoretical model was characterized and calibrated using a known sample, namely a birefringent quarter wave retarder with the fast axis at different orientations (to simulate the corneal layer of the eye). Once this was achieved, the system was used to obtain data on ex vivo rabbit eyes. The data was collected for different positions on each eye. The experimental results were then compared with the theoretical results and the intensity variations due to changes in the polarization-state of the input incident light were analyzed. The change in the intensity for the elements of the Mueller matrix characterizes the optical nature of the corneal layer of the rabbit eye. The experimental results were in good agreement with the theoretical results.