Development and test of a compact optical device for the measurement of polarization threshold perception based on Haidinger's brushes.

Haidinger's brushes are an entoptic phenomenon consisting in the perception of a yellowish bow tie in the presence of linearly polarized white light. The pattern arises from the peculiar spatial distribution of dichroic carotenoid molecules in the macula, forming a sort of embedded radial polarizer for blue light in the fovea. We present here the latest results in the development and test of a compact and robust optical device for the measurement of the polarization threshold based on the perception of Hadinger's brushes and discuss possible applications to the early diagnosis of macular diseases.