Editing Color blindness (section)

===Based on severity===
Based on clinical appearance, color blindness may be described as total or partial. Total color blindness (monochromacy) is much less common than partial color blindness.<ref>{{cite web |url=http://micro.magnet.fsu.edu/primer/lightandcolor/humanvisionhome.html |title=Human Vision and Color Perception |publisher=[[Florida State University]] |last1=Spring |first1=Kenneth R. |first2=Matthew J. |last2=Parry-Hill |first3=Thomas J. |last3=Fellers |first4=Michael W. |last4=Davidson |access-date=2007-04-05 |url-status=live |archive-url=https://web.archive.org/web/20070827191749/http://micro.magnet.fsu.edu/primer/lightandcolor/humanvisionhome.html |archive-date=2007-08-27 }}</ref>  Partial color blindness includes dichromacy and anomalous trichromacy, but is often clinically defined as mild, moderate or strong.

====Monochromacy====
{{Main|Monochromacy}}
Monochromacy is often called ''total color blindness'' since there is no ability to see color. Although the term may refer to acquired disorders such as [[cerebral achromatopsia]], it typically refers to congenital color vision disorders, namely [[Achromatopsia|rod monochromacy]] and [[blue cone monochromacy]]).<ref name=":0">{{cite web|url=http://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/|title=Types of Colour Blindness|work=Colour Blind Awareness|url-status=live|archive-url=https://web.archive.org/web/20140529052207/http://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/|archive-date=2014-05-29}}</ref><ref name=blom>
{{cite book |title       = A Dictionary of Hallucinations |first       = Jan Dirk |last        = Blom |publisher   = Springer |year        = 2009 |isbn        = 978-1-4419-1222-0 |page        = 4 |url=https://books.google.com/books?id=KJtQptBcZloC&pg=PA4 |url-status     = live |archive-url  = https://web.archive.org/web/20161227164302/https://books.google.com/books?id=KJtQptBcZloC&pg=PA4 |archive-date = 2016-12-27 }}</ref>

In cerebral achromatopsia, a person cannot perceive colors even though the eyes are capable of distinguishing them. Some sources do not consider these to be true color blindness, because the failure is of perception, not of vision. They are forms of [[visual agnosia]].<ref name=blom/>

[[Monochromacy]] is the condition of possessing only a single channel for conveying information about color. Monochromats are unable to distinguish any colors and perceive only variations in brightness. Congenital monochromacy occurs in two primary forms:
# Rod monochromacy, frequently called complete [[achromatopsia]], where the retina contains no cone cells, so that in addition to the absence of color discrimination, vision in lights of normal intensity is difficult.
# Cone monochromacy is the condition of having only a single class of cone. A cone monochromat can have good pattern vision at normal daylight levels, but will not be able to distinguish hues. Cone monochromacy is divided into classes defined by the single remaining cone class. However, red and green cone monochromats have not been definitively described in the literature. [[Blue cone monochromacy]] is caused by lack of functionality of L (red) and M (green) cones, and is therefore mediated by the same genes as red–green color blindness (on the X chromosome). Peak spectral sensitivities are in the blue region of the visible spectrum (near 440&nbsp;nm). People with this condition generally show [[nystagmus]] ("jiggling eyes"), [[photophobia]] (light sensitivity), reduced [[visual acuity]], and [[myopia]] (nearsightedness).<ref>{{cite journal | vauthors = Weiss AH, Biersdorf WR | title = Blue cone monochromatism | journal = Journal of Pediatric Ophthalmology and Strabismus | volume = 26 | issue = 5 | pages = 218–23 | year = 1989 | doi = 10.3928/0191-3913-19890901-04 | pmid = 2795409 | s2cid = 23037026 }}</ref> Visual acuity usually falls to the 20/50 to 20/400 range.

====Dichromacy====
{{main|Dichromacy}}
Dichromats can match any color they see with some mixture of just two [[primary color]]s (in contrast to those with normal sight ([[Trichromacy|trichromats]]) who can distinguish three primary colors).<ref name=":0" /> Dichromats usually know they have a color vision problem, and it can affect their daily lives. Dichromacy in humans includes protanopia, deuteranopia, and tritanopia. Out of the male population, 2% have severe difficulties distinguishing between red, orange, yellow, and green (orange and yellow are different combinations of red and green light). Colors in this range, which appear very different to a normal viewer, appear to a dichromat to be the same or a similar color. The terms protanopia, deuteranopia, and tritanopia come from Greek, and respectively mean "inability to see (''anopia'') with the first (''prot-''), second (''deuter-''), or third (''trit-'') [cone]".

====Anomalous trichromacy====
Anomalous trichromacy is the mildest type of color deficiency{{Citation needed|date=February 2025}}, but the severity ranges from almost dichromacy (strong) to almost normal trichromacy (mild).<ref>{{cite journal | vauthors = Simunovic MP | title = Colour vision deficiency | journal = Eye | volume = 24 | issue = 5 | pages = 747–55 | date = May 2010 | pmid = 19927164 | doi = 10.1038/eye.2009.251 | doi-access = free }}</ref> In fact, many mild anomalous trichromats have very little difficulty carrying out tasks that require normal color vision and some may not even be aware that they have a color vision deficiency. The types of anomalous trichromacy include protanomaly, deuteranomaly and tritanomaly.  It is approximately three times more common than [[dichromacy]].<ref>{{Cite journal |doi=10.1016/j.gde.2006.04.002|title=Genetics of variation in human color vision and the retinal cone mosaic|year=2006|last1=Deeb|first1=Samir S.|journal=Current Opinion in Genetics & Development|volume=16|issue=3|pages=301–307|pmid=16647849}}</ref> Anomalous trichromats exhibit [[trichromacy]], but the color matches they make differ from normal trichromats. In order to match a given spectral yellow light, protanomalous observers need more red light in a red/green mixture than a normal observer, and deuteranomalous observers need more green. This difference can be measured by an instrument called an [[Anomaloscope]], where red and green lights are mixed by a subject to match a yellow light.<ref>{{cite journal|doi=10.1016/0042-6989(79)90209-8|title=Optimization of a Rayleigh-type equation for the detection of tritanomaly|year=1979|last1=Moreland|first1=J.D.|last2=Kerr|first2=J.|journal=Vision Research|volume=19|issue=12|pages=1369–1375|pmid=316945|s2cid=29379397 }}</ref>