What Is Achromatopsia? Congenital achromatopsia is a rare hereditary vision disorder which affects 1 person in 33,000 in the U. S. The incidence varies in different parts of the world. Persons who have achromatopsia (sometimes called achromatopia) do not have normal "cone vision." In the retinas of normal eyes there are 6 million cone photoreceptors, located mostly at the center of the retina. There are complete and incomplete forms of achromatopsia. Persons with complete achromatopsia must re ...