Everything you wanted to know about the human visual system, but were afraid to ask, can be found in Adler's Physiology of the Eye. It's worth its $100 price tag.
For a survey of the physiology of animal eyes and photoreceptors, see Wolken's book. The discussion covers the full range of the animal kingdom, including types of eyes you're unlikely to have heard of.
Last modified Friday, 12-Sep-1997 14:58:46 PDT