A polychromatic double-pass setup was developed to study the effects of wavelength and polarization onretinal image quality. The results show that the central part of the images was similar for all wavelengths(543, 633 and 780 nm) and polarization states. However, the image tails increased signiﬁcantly whenusing infrared light for all the polarization states used. For the set of subjects involved in the study, oculardiattenuation presented individual differences, however signiﬁcant changes were not found across thedifferent wavelengths. Moreover the Stokes vectors providing the maximum intensity transmittance varied across subjects and corresponded to elliptically polarized light. These non-negligible diattenuationeffects might affect the performance of clinical devices which only take into account ocular birefringence.