Haidinger's brushes

Haidinger's brushes

An entoptic phenomenon observed when viewing a large diffusely illuminated blue field through a polarizer. It appears as a pair of yellow, brush-like shapes, which seem to radiate from the point of fixation. The brushes are believed to be due to double refraction by the radially oriented fibres of Henle around the fovea. This phenomenon is used in detecting and treating eccentric fixation.
References in periodicals archive ?
Most participants were able to detect Haidinger's brushes to a threshold of 56% polarisation, but some were able to drop to less than a quarter, as low as 23% polarisation.
The two entoptic phenomena strongly associated with the macular pigment are Haidinger's brushes and Maxwell's spot, both of which are only seen under highly specific experimental conditions.
They found excellent agreement in a comparison of the visibility of Haidinger's brushes in light of various wavelengths to the spectral absorption of xanthophylls, a yellow carotenoid pigment, which is similar to if not identical with, the macular pigment.