We have studied the polarization parameters of the human eye associated with ocular birefringence from double-pass retinal images by using an imaging linear polariscope. A series of nine images corresponding to combinations of linear independent polarization states in both generator and analyser units was recorded. Retardation and azimuthal angle obtained when considering the human eye as a linear retarder have been compared to those calculated with a Mueller matrix polarimeter. Results in young eyes show only small differences, of about 2◦ for azimuth and 6◦ for retardation, between these methods. Moreover, changes in the polarization state of the central part of double-pass images are very different from those corresponding to the tails. Although the simpler linear polariscope is mainly designed for studies in physiological optics and clinical diagnosis, it can also be used for the analysis of in vitro biological samples and crystals.