The mildest forms of colorblindness are hard to detect, so if you have the smallest inkling that you may be colorblind, then you almost certainly are, at least mildly. Taking an online test is fairly accurate, and a great first step to answering this question.
If you routinely see your child making color mistakes (naming the wrong color, painting the ocean purple, etc.), then there is a strong change they are colorblind. By the time a child is three years old and verbal, they should be able to complete a colorblind test at an optometrist such as the Ishihara Tracing Plates, or the HRR test.
It can happen. Generally, since the colorblind don't get any kind of special dispensation such as extra exam time, there is no harm in someone pretending to be colorblind. However, if you are concerned, then tests applied by eye doctors do have built-in mechanisms - like control plates - to detect "malingering". Best to warn them beforehand, or course.
There is no cure that is available. There are some promising possibilities, namely gene therapy, which was able to 'cure' a 'colorblind' monkey. However, the human application of these techniques for red-green colorblindness it still at least a decade away. As of 2022, clinical trials are underway for the gene therapy for the much more severe Achromatopsia.
The glasses do not cure colorblindness or allow someone to see with normal color vision. However, they may enhance color vision or make some color vision tasks easier, depending on the context. Whether someone thinks they are worth it, is dependent on so many factors. However, they have a pretty liberal money-back guarantee, so they are usually worth a try.
The common color correction glasses include EnChroma, Colorlite, Pilestone, ColorMAX and Vino Optics. Of them, EnChroma works on a significantly different principle. The others may not be significantly better than a simple pair of magenta tinted sunglasses. Of course, it is important to say that magenta-tinted sunglasses can be immensely useful to the colorblind, often more so than the 'notch filtered' glasses from EnChroma. From testimonials online, it seems there is not a clear preference for any one company, besides to say that the frame quality of EnChromas are superior, especially to Pilestones.
The easiest way to take a colorblind test is on your computer/phone. Make sure any color filters are disabled (such as blue-blocking filters), then take one of the following tests: Ishihara test, or similar. Ophthalmologists will generally be able to apply even more definitive tests such as an Anomaloscope.
The Ishihara Test is the most common test for color vision, but also one of the strictest (hardest to pass). The easiest way to beat the Ishihara Test is to get tested with a different standard like the Farnsworth Lantern, if available. Other tips:
- Practicing the Ishihara Plates beforehand can slightly increase your chances to pass.
- Some colorblind glasses or contacts can make the test easily passable, but the optometrist will certainly not allow it.
- Memorization of the answers is possible, but of limited utility since most doctors will randomize the order.
Only in a few countries are the colorblind considered to be disabled, but the topic is contentious. Those who say "no" claim that colorblindness affects daily life way less than "typical" disabilities like paraplegia or blindness. Those who say "yes" often cite the long list of restricted careers. I believe the question kind of misses the point. Whether something is a disability should not have any bearing on whether that condition is "worthy" of inclusive design. On its own, left-handedness is decidedly not a disability, but being left-handed in a society designed for the right-handed can feel like a disability when there is not sufficient inclusive design.
Most of the problems with being colorblind are little more than mild inconveniences. The biggest restriction is in the choice of careers, where color vision may be safety critical. The list of restrictive or difficult jobs is actually quite long.
Dichromat.com offers a comprehensive list of careers that are either restricted or inaccessible to the colorblind. Some examples:
- pilot/police - heavily restricted in most countries
- accountant/driver - restricted in some countries
- geologist/chemist - can be very difficult, with many jobs screening colorblind applicants
- doctor/chef - not restricted, but can be difficult or require several coping mechanisms depending on the area of expertise.
Generally, military pilots are held to very high standards when it comes to color vision, requiring not only normal color vision, but sometimes also superior color vision. Civilian pilots must be able to pass very disparate color vision standards, which ensure that the pilot can distinguish the PAPI or ATC Light Gun. When you can't pass one of the standards (such as the FaLant), then you can still be cleared to fly, but would be restricted to daytime flying, which restricts you from being a commercial pilot.
In most western countries, the colorblind have no restrictions against driving. Even Achromats can get driver's licenses with the help of Bioptic Driving in many US states. Other countries can restrict the colorblind from driving, either in full (China) or in part (India).
1 in 12 boys (~8%) and 1 in 200 girls (~0.5%) are colorblind. Girls are much less likely to be colorblind because the genetics of color vision are linked to the X-Chromosome. However, about 1 in 16 colorblind individuals are female, which is not exceedingly rare. This YouTube Video describes the genetics of colorblindness.
Tetrachromatic Vision (Tetrachromacy) is a type of color vision common in non-mammalian animals that uses 4 cones instead of the 3 cones (Trichromacy) that are typical of human color vision. All else similar, Tetrachromats have better color vision than their trichromatic counterparts, and are often described as having "super color vision". Most humans are trichromats, but a handful claim to be tetrachromats, which would give them the ability to see far more colors than the rest of us.
It is rare, but unilateral CVD, where one eye is colorblind is possible. This is generally not a congenital defect (present at birth), but rather an acquired defect due to the retinal trauma (shining lasers in your eye) or other pathology (e.g. brain tumors). If the condition is progressive (it is getting worse), than urgent attention from an ophthalmologist is necessary.
The vast majority of the colorblind have congenital CVD, which is present at birth and is stationary (does not change significantly throughout their life). Acquired CVD is acquired during your lifetime. It can be gradual or sudden and can stem from:
A practice called photobleaching, where one class of cones in your eye is 'fatigued' can lead to temporary colorblindness. This is a perennial trick on social media, where someone will shine a bright light through a closed eyelid, to selectively photobleach the red cones, and therefore experience vision similar to a protan. This has never been proven safe to do.
Excluding the more severe forms, there are three classes of colorblindness: protan, deutan and tritan. Protan/Duetan are collectively known as red-green colorblindness and are very similar. So much so that they can be difficult to reliably distinguish. Tritan is known as blue-yellow colorblindness and is very different than the other two. It is also much rarer and on average milder. Most tests do not detect blue-yellow colorblindness. Most tests for red-green colorblindness will also try to diagnose as protan or deutan, with pretty accurate results. However, the only way to confidently determine if you are a protan or deutan is with an Anomaloscope or device such as the Medmont C-100.
In Oliver Sacks' article "The Case of the Colorblind Painter", a man who became colorblind after an accident at the age of 65 became "almost suicidally depressed". For the rest of us that were born with congenital CVD, there is doubtful much of an effect on our mental health.
There is no such thing as 'perfect' color vision. Color vision can always hypothetically improve, and many animals possibly have better color vision than humans. However, the typical non-colorblind human has an upper limit to their color vision with only a little bit of variability. Of color normal humans, about 68% have average color vision, 16% have low color vision (but not yet 'color deficient'), and another 16% have superior color vision. Some people dislike the term 'normal', so sometimes 'typical' is used in stead.
The naming convention of colorblindnesses, which has existed in its current form since 1897, separates dichromats (protanopia, deuteranopia, tritanopia) from anomalous trichromats (protanomaly, deuteranomaly, tritanomaly). The severity of anomalous trichromacy can range from the extremes of normal color vision to dichromacy, so a severe anomalous trichromat has vision that much more resembles a dichromat than it does a mild anomalous trichromat of the same type. Usually, colorblind tests will define a result as being mild, moderate or severe. Not only are these not consistent terms between two tests, they also don't line up with the definitions of dichromacy and anomalous trichromacy. For example, a severe/strong deutan test result can mean either strong deuteranomaly or deuteranopia. Definitively differentiating between them is very difficult and generally relies on an ERG or genetic testing. Every other indication is only a guess of varying confidence. However, differentiating between the two is seldom necessary.
This is a difficult question, since its is difficult to fully classify all aspects of color vision. Some animals (e.g. mice) have wider visible spectra, but are dichromats instead of trichromats. Some animals have more opsins than humans (e.g. Mantis Shrimp), but likely do not have the opponent channels required to take advantage of all of these different opsins. Some animals (e.g. Cuttlefish) are able to detect the polarization of light, which we cannot do. Other animals (e.g. Blue Bottle Butterfly), appear to see more colors than the humans, but presuming they have better color vision than humans is even cautioned against by the researchers themselves. For the time being, there is no clear king of color vision.
Thanks! If you are trying to make your graphic, game, content, etc. accessible to the colorblind, it is very much appreciated. Here are some tips:
- Try viewing your creation through a colorblind simulator. Some are available through the Tools page. If you see a problem there, then the colorblind would probably also see that problem
- For colorscales or continuous colormaps, use a colorblind friendly version like Parula or Viridis.
- For groups of distinct colors (e.g. board game player colors), pick colors using the Adobe Color Accessibility Tools (Color Blind Safe).
- For video games, it is always preferred to let the user pick their preferred colors for specific elements (e.g. enemy outlines) instead of offering a global "filter" that may help, but distorts the entire game and has a high chance of being useless or making things worse.
Many users of hallucinogens report seeing colors they have never experienced before while under the influence. Anthony  used self-reported data to show that users of LSD believed their colorblindness was alleviated while under the influence. While it makes sense to believe that a user (colorblind or color normal) could experience colors that they would otherwise not be able to see naturally (e.g. impossible colors), there is no possible explanation for how LSD (or any change of neurological state) can help an individual differentiate between two colors that are normally metamers to them.