Editing Color blindness (section)

==Diagnosis==
===Color vision test===
{{main|Color vision test}}
[[Image:Ishihara compare 1.jpg|right|thumb|upright=1.4|An Ishihara test image as seen by subjects with normal color vision and by those with a variety of color deficiencies]]
The main method for diagnosing a color vision deficiency is in testing the color vision directly. The [[Ishihara color test]] is the test most often used to detect red–green deficiencies and most often recognized by the public.<ref name="Gor1998"/> Some tests are clinical in nature, designed to be fast, simple, and effective at identifying broad categories of color blindness. Others focus on precision and are generally available only in academic settings.<ref>{{cite journal | vauthors = Toufeeq A | title = Specifying colours for colour vision testing using computer graphics | journal = Eye | volume = 18 | issue = 10 | pages = 1001–5 | date = October 2004 | pmid = 15192692 | doi = 10.1038/sj.eye.6701378 | doi-access = free }}</ref>
* '''Pseudoisochromatic plates''', a classification which includes the [[Ishihara color test]] and HRR test, embed a figure in the plate as a number of spots surrounded by spots of a slightly different color. These colors must appear identical ([[Metamerism (color)|metameric]]) to the color blind but distinguishable to color normals. Pseudoisochromatic plates are used as screening tools because they are cheap, fast, and simple, but they do not provide precise diagnosis of CVD.
* '''Lanterns''', such as the [[Farnsworth Lantern Test]], project small colored lights to a subject, who is required to identify the color of the lights. The colors are those of typical signal lights, i.e. red, green, and yellow, which also happen to be colors of confusion of red–green CVD. Lanterns do not diagnose color blindness, but they are occupational screening tests to ensure an applicant has sufficient color discrimination to be able to perform a job.
[[Image:Huetestfmd15-2.jpg|right|thumb|upright=1.4|A Farnsworth D-15 test]]
* '''Arrangement tests''' can be used as screening or diagnostic tools. The [[Farnsworth–Munsell 100 hue test#100 hue test|Farnsworth–Munsell 100 hue test]] is very sensitive, but the [[Farnsworth–Munsell 100 hue test#D15 test|Farnsworth D-15]] is a simplified version used specifically for screening for CVD. In either case, the subject is asked to arrange a set of colored caps or chips to form a gradual transition of color between two anchor caps.<ref>{{cite journal | vauthors = Kinnear PR, Sahraie A | title = New Farnsworth–Munsell 100 hue test norms of normal observers for each year of age 5–22 and for age decades 30–70 | journal = The British Journal of Ophthalmology | volume = 86 | issue = 12 | pages = 1408–11 | date = December 2002 | pmid = 12446376 | pmc = 1771429 | doi = 10.1136/bjo.86.12.1408 }}</ref>
* '''[[Anomaloscope]]s''' are typically designed to detect red–green deficiencies and are based on the [[anomaloscope#Principle|Rayleigh match]], which compares a mixture of red and green light in variable proportions to a fixed spectral yellow of variable luminosity. The subject must change the two variables until the colors appear to match. They are expensive and require expertise to administer, so they are generally only used in academic settings.

===Genetic testing===
While genetic testing cannot directly evaluate a subject's color vision ([[phenotype]]), most congenital color vision deficiencies are well-correlated with [[genotype]]. Therefore, the [[genotype]] can be directly evaluated and used to predict the [[phenotype]]. This is especially useful for [[Progressive disease|progressive]] forms that do not have a strongly color deficient phenotype at a young age. However, it can also be used to sequence the L- and M-Opsins on the X-chromosome, since the most common [[allele]]s of these two genes are known and have even been related to exact [[Spectral sensitivity|spectral sensitivities]] and peak wavelengths. A subject's color vision can therefore be classified through [[genetic testing]],<ref name=GHR2019>{{Cite web|url=https://ghr.nlm.nih.gov/condition/color-vision-deficiency|title=Color vision deficiency|last=Reference|first=Genetics Home|website=Genetics Home Reference|language=en|access-date=2019-05-06|archive-date=10 January 2020|archive-url=https://web.archive.org/web/20200110053737/https://ghr.nlm.nih.gov/condition/color-vision-deficiency|url-status=live}}</ref> but this is just a prediction of the phenotype, since color vision can be affected by countless non-genetic factors such as your [[Retinal mosaic|cone mosaic]].