It is the result of the too great intensity of the light incident upon the retina, and which in normal eyeballs is adequately diminished by the absorptive power of the pigmentary material.
This condition is one marked by unsteadiness - a sort of flickering rolling - of the eyeballs, and it becomes more marked as they endeavour to adjust their accommodation to near objects.
Other individual rabbits, but belonging to no particular breed, are similarly marked, but in addition the eyeballs are black.
Some domesticated mice are entirely white with the exception that they have black eyeballs; and individuals of this type are known in which there is a reduction of pigment in the eyeballs, and since the colour of the blood is then partially visible these appear of a reddish-black colour.
Occasionally the piebald patches tend to be symmetrically arranged, and sometimes the eyeballs are pigmentless (pink) and sometimes pigmented (black).