In 1942, Sloan first distinguished typical and atypical achromatopsia, differentiated mainly on the inheritance patterns. In 1953, Weale theorized that the atypical achromatopsia must stem from cone-monochromatism, but estimated a prevalence of only 1 in 100 million. In the early 1960's, the inheritance of atypical achromatopsia led to a name change to x-linked achromatopsia, and at the same time, several studies demonstrated that Blue cone monochromats retain some Blue yellow color vision. A significant discovery was announced in 1989 (and 1993) by Nathans et al. who identified the genes causing Blue cone monochromacy.
