Editing Color blindness (section)

===Based on affected cone===
There are two major types of color blindness: difficulty distinguishing between red and green, and difficulty distinguishing between blue and yellow.<ref>{{cite web|url=http://www.digitalspaceart.com/articles/ColorBlindness.pdf |title=Accommodating Color Blindness |first=Paul S. |last=Hoffman |access-date=2009-07-01 |url-status=dead |archive-url=https://web.archive.org/web/20080515103432/http://www.digitalspaceart.com/articles/ColorBlindness.pdf |archive-date=15 May 2008 }}</ref><ref>{{cite web|url=http://healthlink.mcw.edu/article/999211295.html |title=Severity of Colorblindness Varies |last=Neitz |first=Maureen E. |author-link= Maureen Neitz |publisher=[[Medical College of Wisconsin]] |access-date=2007-04-05 |url-status=dead |archive-url=https://web.archive.org/web/20070205055320/http://healthlink.mcw.edu/article/999211295.html |archive-date=5 February 2007 }}</ref>{{Dubious |Tritanopia|date=September 2020}} These definitions are based on the [[phenotype]] of the partial color blindness. Clinically, it is more common to use a genotypical definition, which describes which [[cone cell|cone]]/[[opsin]] is affected.

====Red–green color blindness====
Red–green color blindness includes '''protan''' and '''deutan''' CVD. Protan CVD is related to the L-cone and includes protanomaly (anomalous trichromacy) and protanopia (dichromacy). Deutan CVD is related to the M-cone and includes deuteranomaly (anomalous trichromacy) and deuteranopia (dichromacy).<ref name=pmid21774112>
{{cite journal
 | last = Wong |first = B.
 | date = June 2011
 | title = Color blindness
 | journal = Nature Methods
 | volume = 8 | issue = 6 | pages = 441
 | s2cid = 36690778 | pmid = 21774112
 | doi = 10.1038/nmeth.1618
}}
</ref><ref>{{cite journal | vauthors = Neitz J, Neitz M | title = The genetics of normal and defective color vision | journal = Vision Research | volume = 51 | issue = 7 | pages = 633–51 | date = April 2011 | pmid = 21167193 | pmc = 3075382 | doi = 10.1016/j.visres.2010.12.002 }}</ref> The phenotype (visual experience) of deutans and protans is quite similar. Common colors of confusion include red/brown/green/yellow as well as blue/purple. Both forms are almost always symptomatic of [[congenital red–green color blindness]], so affects males disproportionately more than females.<ref name=harrison>{{cite book|last1=Harrison|first1=G.A.|last2=Tanner|first2=J.M.|last3=Pilbeam|first3=D.R.|last4=Baker|first4=P.T.|title=Human Biology|pages=[https://archive.org/details/humanbiologyintr00gaha/page/183 183–187, 287–290]|location=Oxford|publisher=Oxford University Press|date=1988|isbn=978-0-19-854144-8|url=https://archive.org/details/humanbiologyintr00gaha/page/183}}</ref> This form of color blindness is sometimes referred to as ''daltonism'' after [[John Dalton (scientist)|John Dalton]], who had red–green dichromacy. In some languages, ''daltonism'' is still used to describe red–green color blindness.

[[File:ConeMosaics.jpg|thumb|upright=1.4|Illustration of the distribution of cone cells in the [[Fovea centralis|fovea]] of an individual with normal color vision (left), and a color blind (protanopic) retina. The center of the fovea holds very few blue-sensitive cones.]]
{{anchor|Protanopia}}
{{anchor|Protanomaly}}
{{anchor|Protan}}
* '''Protan''' (2% of males): Lacking, or possessing anomalous [[OPN1LW|L-opsins]] for long-wavelength sensitive cone cells. Protans have a neutral point at a [[cyan]]-like wavelength around 492&nbsp;nm (see [[spectral color]] for comparison)—that is, they cannot discriminate light of this wavelength from [[white]]. For a protanope, the brightness of red is much reduced compared to normal.<ref name="Genetics">{{cite journal|last1=Neitz|first1=Jay|first2=Maureen|last2=Neitz|title=The genetics of normal and defective color vision|journal=Vision Research|volume=51|issue=7|date=2011|pages=633–651| doi=10.1016/j.visres.2010.12.002|pmid=21167193|pmc=3075382}}</ref> This dimming can be so pronounced that reds may be confused with black or dark gray, and red traffic lights may appear to be extinguished. They may learn to distinguish reds from yellows primarily on the basis of their apparent brightness or lightness, not on any perceptible hue difference. [[shades of violet|Violet]], [[shades of purple|lavender, and purple]] are indistinguishable from various [[shades of blue]]. A very few people have been found who have one normal eye and one protanopic eye. These ''unilateral dichromats'' report that with only their protanopic eye open, they see wavelengths shorter than neutral point as blue and those longer than it as yellow.
{{anchor|Deuteranopia}}
{{anchor|Deuteranomaly}}
{{anchor|Deutan}}
* '''Deutan''' (6% of males): Lacking, or possessing anomalous [[OPN1MW|M-opsin]]s for medium-wavelength sensitive cone cells. Their neutral point is at a slightly longer wavelength, 498&nbsp;nm, a more greenish hue of cyan. Deutans have the same hue discrimination problems as protans, but without the dimming of long wavelengths. Deuteranopic unilateral dichromats report that with only their deuteranopic eye open, they see wavelengths shorter than neutral point as blue and longer than it as yellow.<ref>{{cite book |title= Contributions to color science |editor1-last= MacAdam |editor1-first=David L. |editor2-last=Judd |editor2-first=Deane B. |publisher=NBS |year=1979 |page=584 |url=https://books.google.com/books?id=jgz_iI8NAzYC&pg=PA584}}</ref>

====Blue–yellow color blindness====
Blue–yellow color blindness includes '''tritan''' CVD. Tritan CVD is related to the S-cone and includes tritanomaly (anomalous trichromacy) and tritanopia (dichromacy). Blue–yellow color blindness is much less common than red–green color blindness, and more often has acquired causes than genetic. Tritans have difficulty discerning between bluish and greenish hues.<ref>Steefel, Lorraine T., and Timothy E. Moore, PhD. "Color Blindness." ''The Gale Encyclopedia of Nursing and Allied Health'', edited by Jacqueline L. Longe, 4th ed., vol. 2, Gale, 2018, pp. 890–892. ''Gale eBooks'', Accessed 29 Dec. 2021.</ref> Tritans have a neutral point at 571&nbsp;nm (yellowish).<ref>{{Cite journal |last=Graham |first=C. H. |last2=Hsia |first2=Y. |date=1958-03-28 |title=Color defect and color theory; studies of normal and colorblind persons, including a subject color-blind in one eye but not in the other |url=https://pubmed.ncbi.nlm.nih.gov/13529033/ |journal=Science |volume=127 |issue=3300 |pages=675–682 |doi=10.1126/science.127.3300.675 |issn=0036-8075 |pmid=13529033}}</ref><ref>{{Cite web |title=SBFAQ Part 4: Color Blindness |url=https://visualexpert.com/Resources/cfaqPart4.html |access-date=2025-03-09 |website=visualexpert.com}}</ref>

{{anchor|Tritanopia}}
{{anchor|Tritanomaly}}
{{anchor|Tritan}}
* '''Tritan''' (<&nbsp;0.01% of individuals): Lacking, or possessing anomalous [[OPN1SW|S-opsins]] or short-wavelength sensitive cone cells. Tritans see short-wavelength colors ([[blue]], [[indigo]] and spectral [[Violet (color)|violet]]) as greenish and drastically dimmed, some of these colors even as [[black]]. Yellow and orange are indistinguishable from [[white]] and [[pink]] respectively, and purple colors are perceived as various [[shades of red]]. Unlike protans and deutans, the mutation for this color blindness is carried on chromosome 7. Therefore, it is not sex-linked (equally prevalent in both males and females). The OMIM gene code for this mutation is 304000 "Colorblindness, Partial Tritanomaly".<ref>{{cite web | title = Disease-causing Mutations and protein structure |url=http://www.biochem.ucl.ac.uk/bsm/humgen/chr__034.html#304000 | archive-url=https://web.archive.org/web/20050501081119/http://www.biochem.ucl.ac.uk/bsm/humgen/chr__034.html#304000 | url-status = dead | archive-date = 2005-05-01 | publisher = UCL Biochemistry BSM Group | access-date = 2007-04-02 }}</ref>
{{anchor|Tetartanopia}}
{{anchor|Tetartanomaly}}
{{anchor|Tetartan}}
* '''Tetartan''' is a hypothetical "fourth type" of color blindness, and a type of blue–yellow color blindness. Given the molecular basis of human color vision, it is unlikely this type could exist.<ref>{{Cite journal |last1=V |first1=Ionica |last2=Gastaud |first2=P |title=Test chromatique pour dépistage et étalonnage des dyschromatopsies |trans-title=Color vision test for detection and evaluation of dyschromatopsia |url=https://pubmed.ncbi.nlm.nih.gov/9033889/ |journal=Journal Français d'Ophtalmologie |date=1996 |language=fr |volume=19 |issue=11 |pages=679–688 |pmid=9033889 |access-date=13 June 2024 |archive-date=13 June 2024 |archive-url=https://web.archive.org/web/20240613193630/https://pubmed.ncbi.nlm.nih.gov/9033889/ |url-status=live }}</ref>