For comparing the birefringence of the RNFL with previously published data, we additionally calculated quantitative birefringence values based on a method described in Refs. 31 and 54. The retardation values, within the RNFL, are plotted over the A-scan depth and with a linear fit, the slope of the retardation is determined and, thereby, the birefringence. In a second step, an annular area centered at the opticnerve head, with an inner radius of approximately 1.3 mm and an outer radius of approximately 1.7 mm, is divided in four quadrants. The four quadrants are temporal (spanning an angle of 50 deg), superior (120 deg), nasal (70 deg), inferior (120 deg), and are the same quadrants as used for the temporal, superior, nasal, inferior, temporal diagrams of scanning laser polarimetry, a common tool in glaucoma diagnostics for examining the RNFL and its degradation. The used algorithm only delivers reliable data if the RNFL thickness is above a certain threshold, therefore, we decided to calculate quantitative data only for the superior and inferior quadrant. The birefringence values, within these sectors, were averaged over the respective A-scans. Birefringence values extracted for the superior and inferior region from the measurements performed in the three measured volunteers vary between and . This seems to be lower than the values that can be found in literature. Cense et al. reported in 2002 birefringence values of near the optic nerve head region and, in a later work, he presented values ranging from 1.2 to for different areas around the optic nerve head.31,54 Yamanari et al. reported values from 1.2 to around the optic nerve head and Mujat et al. reported an average birefringence of for the RNFL.51,55 Kemp et al. found values of for RNFL birefringence in the inferior region measured in an anesthetized primate.56 All values, mentioned here, were measured with PS-OCT set-ups working at a central wavelength of 840 nm. A recent paper also presents birefringence values, measured with a PS-OCT set-up, working at a central wavelength of 1060 nm.57 The values are in range of 2.94 to around the optic nerve head.