Monochromacy and Achromatopsia
Monochromacy and Achromatopsia describes a range of conditions that include rod-Monochromacy, S-cone Monochromacy and Achromatopsia. Sometimes these are collectively referred to as types of achromatopsia, as the word “achromat” meaning “no color.” However, not all cases of achromatopsia have “no color” vision. Similar to other forms of color blindness, achromatopsia can be graded as incomplete (partial) achromatopsia or complete achromatopsia (total color blindness). Achromatopsia is often associated with light sensitivity, photophobia, and glare sensitivity. In some cases, low vision disorders such as progressive cone dystrophy or retinitis pigmentosa can cause a gradual deterioration of color vision that eventually turns into complete achromatopsia.
Trichromats, Dichromats, Monochromats are terms used in the vision science community to refer to different possible configurations of the human visual system having three (tri-), di (two) or one (mono) channel of color information. However, these terms are simplified to a great extent, because the true capability of a color vision system also depends on the degree of overlap between the channels, “perceptual noise” within the channels, and the cognitive processing capability for deciphering these signals in the visual cortex of the brain. Most cases of color blindness are considered anomalous trichromacy which means they are effectively operating at somewhere between trichromat (normal color vision with 3 channels) and dichromat (2 channels).
The EnChroma Color Blind Test is specifically designed to determine your type of red-green color blindness (deutan or protan) and level: mild deutan or protan, moderate deutan or protan, or strong deutan or protan. However there are limits to what can be tested with a self-administered online test. If you believe that you may have a color vision deficiency, EnChroma recommends getting a complete eye exam by a qualified eye care professional.