
9.5 Color Vision Impairments 213
Wikipedia [29] provides a short description of all inherited or congenital color
deciencies. Color blindness may be acquired or inherited, with three types of
inherited or congenital color vision deciencies: monochromacy, dichromacy,
and anomalous trichromacy.
Monochromacy, also known as total color blindness, is the lack of ability to
distinguish colors, caused by the absence or defect of a cone. Monochromacy
occurs when two or all three of the cone pigments are missing and color vision is
reduced to one dimension.
• Rod monochromacy (achromatopsia) is an exceedingly rare, nonpro-
gressive inability to disti ...