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.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann