From OMIMTotal colorblindness, also referred to as rod monochromacy or complete achromatopsia, is a rare congenital autosomal recessive disorder characterized by photophobia, reduced visual acuity, nystagmus, and the complete inability to discriminate between colors. Electroretinographic recordings show that in achromatopsia the rod photoreceptor function is normal, whereas cone photoreceptor responses are absent (summary by Kohl et al., 1998).
Genetic Heterogeneity of Total Achromatopsia
A form of achromatopsia previously designated achromatopsia-1 (ACHM1) was later found to be the same as achromatopsia-3 (ACHM3; 262300), caused by mutation in the CNGB3 gene (605080). ACHM4 (613856) is caused by mutation in the GNAT2 gene (139340); ACHM5 (613093) is caused by mutation in the PDE6C gene (600827); ACHM6 (see 610024) is caused by mutation in the PDE6H gene (601190); and ACHM7 (616517) is caused by mutation in the ATF6 gene (605537).
http://www.omim.org/entry/216900 From MedlinePlus GeneticsAchromatopsia also involves other problems with vision, including an increased sensitivity to light and glare (photophobia), involuntary back-and-forth eye movements (nystagmus), and significantly reduced sharpness of vision (low visual acuity). Affected individuals can also have farsightedness (hyperopia) or, less commonly, nearsightedness (myopia). These vision problems develop in the first few months of life.
Achromatopsia is different from the more common forms of color vision deficiency (also called color blindness), in which people can perceive color but have difficulty distinguishing between certain colors, such as red and green.
Achromatopsia is a condition characterized by a partial or total absence of color vision. People with complete achromatopsia cannot perceive any colors; they see only black, white, and shades of gray. Incomplete achromatopsia is a milder form of the condition that allows some color discrimination.
https://medlineplus.gov/genetics/condition/achromatopsia