[Double refraction of crystals in the lens (spheroliths, "Christmas tree ornaments") and in the vitreous body (scintillatio nivea)].

1. The round, oval, or kidney-shaped, radially built spheroliths of the brown or morgagnian cataract show a double refraction in polarized light of about 0.160 optically positive. This is in accordance with Whewellite (calcium oxalate monohydrate). 2. In crystalline cataracts, there are crystals in polarized light with a mean double refraction of 0.046, which is in accordance with cholesterol (C27H48O). 3. In asteroid hyalinosis of the vitreous, the small bodies consisting of needle-shaped crystals arranged in a radial fashion show a small double refraction of 0.012. Therefore the crystal may be brushite (Ca HPO4 X 2 H2O).