Retinal polarization effects.

Retinal photographs taken with crossed polarizers in the input and recording light paths show a cross or brush pattern overlying the macula. Experiments were done indicating that this pattern is due to the birefringence in cone-photoreceptor outer segments. Haidinger's brushes are also attributed to cone outer segments, but the effect is due to a combination of the dispersion in the birefringence and the dichroism of the outer segments. The objective, polarized-light retinal pattern is shown to be a useful clinical tool for diagnosing diseases affecting the macula.