Tritanopia is a very rare color vision disturbance in which there are only two cone pigments present and a total absence of blue retinal receptors. Blues appear greenish, yellows and oranges appear pinkish, and purple colors appear deep red. It is related to chromosome 7. Unlike protanopia and deuteranopia, tritanopia and tritanomaly are not sex-linked traits and can be acquired rather than inherited and can be reversed in some cases. The disease is Orphanet rare-disease nomenclature identifier Orphanet_88629 (Tritanopia). Also known as: Blue colour blindness, Congenital tritanopia, Tritan colour blindness, blue color blindness.