Perception is reality. For many people, their reality is a reduced ability to perceive colors in the same way that the majority of the world sees them. Also called a color vision deficiency, this condition affects about 1 in 12 males and about 1 in 20 females. Contrary to popular belief, color blindness does not refer to seeing the world in shades of grey. Color blindness simply means that a person has difficulty seeing red, green, or blue, or certain hues of these colors. Only very, very rarely will a person have an inability to see any color at all. Color blindness is considered a mild disability, as it can impact a child’s ability to learn and can disqualify adults from some jobs. However, the majority of people with a color vision deficiency adapt to their condition quite well.
Color blindness is often revealed during childhood when parents may notice that their toddler has difficulty recognizing or identifying different colors. However, color vision deficiencies may go undiagnosed all the way into adulthood. The most obvious symptom of color blindness is the ability to see some colors but not others or the inability to distinguish between different shades of certain colors. For those with mild color vision deficiencies, symptoms can be harder to recognize. The individual may notice that people around them describe objects as being a different shade than what they see. Friends and family might point out that their socks don’t match or a chosen tie doesn’t go with their shirt. Luckily, color blindness is easy to diagnose. You can even test yourself online if you suspect you may be color blind. The tests are just a set of simple visual patterns which measure how well you recognize different colors. In these tests, you look at sets of colored dots and try to find a pattern in them, such as a letter or a number. If you can’t locate the figure, you may have a form of color blindness, and should visit an eye doctor for further diagnosis.
There are a number of possible causes of color blindness. The most common color vision problems are genetic and are inherited from one or both parents. Usually, these hereditary forms of color blindness are present at birth, but despite the condition being genetic, the symptoms may not develop or be diagnosed until much later in life. Color blindness can also be caused by physical damage to the eyes or optic nerve. Glaucoma, diabetes, macular degeneration, cataracts and simple aging can all cause or contribute to color vision problems. Likewise, injury to the eyes, the optic nerve, or to the brain can affect color vision. Some medications may also have side effects which include color vision deficiencies. Consult your doctor immediately if you notice any changes to your ability to distinguish colors as this may be a symptom of underlying injury or an undiagnosed condition.
The colors we perceive are determined by the eye’s cone cells and the information they relay to the brain. People with normal vision are trichromatic, with three cone types: red, green, and blue. Each cone cell contains a light sensitive pigment which is sensitive to a short (blue), medium (green), or long (red) range of wavelengths. People with average cone cells, sensitive to all three primary wavelengths of light, are able to see the full range of colors. A color vision deficiency happens when a person is missing certain cone cells, when the cone cells aren’t functioning, or when they distort the perceived color. There are three major color vision problems; red/green, blue/yellow and monochromacy. Red/green and blue/yellow vision deficiencies occur with two levels of severity: trichromatic (when all three cone types are present) or dichromatic (only two cone types are present).
Red/green color vision deficiencies are the most common forms of color blindness. Red-green color blindness is actually split into subtypes- those that affect the green spectrum of vision and those that affect the red.
Found in about 6% of the male population, this subtype of red-green color blindness is both the mildest and the most common form of color vision deficiency. Deuteranomaly is trichromatic (meaning the individual possesses all 3 cone types) but with a reduced sensitivity to the green wavelength. People with deuteranomaly may commonly confuse reds with greens, bright greens with yellows, pale pinks with light grey, and light blues with lilac. More severe but less common, deuteranopia occurs when the green-receptor cones are missing altogether, producing dichromatic vision. A deuteranope can only perceive between two to three different hues. Deuteranopia affects about 1% of males. Both deuteranomaly and deuteranopia are hereditary and linked to gender.
This is the opposite of deuteranomaly, affecting the sensitivity of the red rather than the green cones. Less common, it affects about 1% of males. People with protanomaly may confuse black with shades of red, some blues with reds or purples, dark brown with dark green, and green with orange. Protanopia is the dichromatic form, caused by the absence of red wavelength cones. Pure reds look black; purples look like blues; oranges appear to be muddy yellows. Both conditions are hereditary and linked to gender, predominantly affecting males.
Tritanomaly is a rare color vision deficiency affecting the sensitivity of the blue cones. Affecting about 1 in 10,000 people, it occurs in both men and women. People with tritanomaly most commonly confuse blues with greens and yellows with purple or violet. The dichromatic version, tritanopia, is the total absence of blue retinal receptors. For people with this color vision deficiency, blues look greenish, yellows and oranges seem pink, and purples look deep red. Although often hereditary, this condition can also have other causes.
Monochromacy, achromatopsia, or total color blindness are conditions of having mostly defective or non-existent cones, causing a complete lack of ability to distinguish colors. People with these forms of color blindness see the world in varying shades of grey. Extremely rare, these conditions are often associated with light sensitivity and poor vision.
Some acquired color vision problems can be treated. For instance, cataract surgery may restore normal color vision. Genetically-inherited color vision deficiencies, though, cannot be treated or corrected as the problem is often associated with the eye’s cones. However, people with color vision deficiencies can learn to compensate for their condition fairly easily. If your child is color blind, make sure their teachers are aware of their limitations, and assist them with color choices at home.
There are a few ways to help make up for a color vision problem, which may be effective for some people. Wearing sunglasses or tinted glasses that block glare has been known to aid some people with color vision deficiencies in being able to differentiate between colors better. Colored contact lenses may also help some people see differences between colors. Recent developments in light filtering lenses are showing promising results in testing, providing some color blind people with a greater ability to distinguish between certain shades, and may someday be a viable option for correcting color vision deficiencies.
Most individuals, however, will develop tricks and techniques for managing their color blindness in their everyday lives. One trick is to learn to look for visual cues like context, location, and brightness, such as memorizing the order of stoplights and the shapes of traffic signs. Others may seek assistance in matching or coordinating clothing choices and stick to particular clothing combinations that they know are acceptable. Whatever ways individuals choose to compensate, the fact is, even those who suffer from significant color vision deficiency are able to live full and happy lives. Their limited color perception does little to diminish their appreciation for the bright and colorful reality they see every day.
Do you see the objects in the images below? If not, you may have a form of colorblindness. Just remember that due to color differences in screens, the accuracy of online color testing is limited. This is not meant to be an official diagnosis of colorblindness. Talk to your eye doctor if you would like to take a complete and accurate test.
You should see a bear, tree, dog, duck, and butterfly.
Test images credit to Gregor Aisch.
Updated Mar 28th, 2014