Quantitative measurement of the degree of polarization uniformity of light backscattered by retinal layers by polarization sensitive OCT

We report on an extension of our previously presented polarization sensitive optical coherence tomography (PS-OCT) technique towards quantitative measurements and imaging of depolarization of light backscattered by the various layers of the human ocular fundus in vivo. We use a state of the art spectral domain PS-OCT instrument that measures a 3D data set within 3 seconds. For measurement of the degree of polarization uniformity, we calculate the Stokes vector of the light backscattered at each point in the imaged volume. We average the Stokes vector elements within an evaluation window that slides over an entire B-scan. From the averaged Stokes vector elements, we calculate the degree of polarization uniformity DOPU within the evaluation window and plot DOPU as a function of position. While anterior retinal layers (and layers below the retinal pigment epithelium (RPE)) show DOPU values near 1, DOPU is only similar to 0.3 - 0.5 in the RPE, with the lowest values found near the center of the fovea. The method might be useful for diagnosing the state of a tissue or for improved segmentation of the RPE.