Reduced retinal deficits in an albino mammal with a cone rich retina: a study of the ganglion cell layer at the area centralis of pigmented and albino grey squirrels.

In all albino mammals studied the central retina is underdeveloped and there is a rod deficit. Central ganglion cell density is approximately 25% below normal. This is not seen in birds, which have a come dominated retina. Here we examine the ganglion cell layer in a cone rich mammal, the squirrel Sciurus carolinensis leucotis. Central cell densities were only < 5% lower in the albinos than in pigmented squirrels. Squirrels are the only known albino mammal to survive successfully in the wild, reinforcing the notion that their visual deficits are minor. The relative immunity of these albino retinae from this deficits may be related to different patterns of cell production between rod and cone dominated eyes.