We have studied the effects of depolarization in the living human eye by using a spatially resolved Mueller-matrix polarimeter [Opt. Lett. 24 (1999) 64]. Results show that the degree of polarization for the central part of double-pass images is about 0.85 and 0.70 for 2 mm and 5 mm of pupil, respectively. This parameter decreases towards the tails of the image. In the plane of the pupil, the degree of polarization also depends on the analyzed area, and it has been related to the different components of the light coming back from the retina. Values of polarizance suggest that the eye presents a slight polarizing power mainly due to the existence of both circular birefringence and dichroic properties. Polarizance is also larger at the central part of double-pass images (about 0.25 on average) and decreases along the radius. In addition, it has been shown that the major retinal layer where the light is reflected does not depend on the state of polarization of the incident light.