Most people who have trouble seeing various spectrums of light have what is called inherited color blindness. The genes that code for correct cone function, which are passed down from their parents, have an error. This is why color blindness tends to run in families. The most common types of color blindness in humans fall under the heading of anomalous trichromacy.
People who are color blind can only see certain colors, depending on which type of color blindness they have. The types of red-green color blindness fall into four different categories. Protanomaly aka red-weak — Individuals have red cones and can usually see some shades of red. Deuteranomaly aka green-weak — Individuals have green cones and can usually see some shades of green.
Ultimately, the different types of red-green color blindness all result in the individual seeing a world the rest of us would describe as murky green with hints of blue and yellow. Browns, oranges and reds are easily confused, and pale shades in general are difficult to distinguish. Blue-yellow color blindness is less common.
The two types of color blindness in this category both make it difficult to tell the difference between blue and green, as well as yellow and red. There are two types of blue-yellow color blindness:. Tritanopia aka blue-blind — Individuals have no blue cones. Tritanomaly aka blue-weak — Individuals have blue cones and can usually see some shades of blue.
All six of these types of color blindness stem from one of the three cone types not functioning to some degree. Though people with anomalous trichromacy may have trouble selecting ripe fruit or reading traffic lights, most colorblind people adapt to live normal lives.
Monochromacy, on the other hand, can be quite challenging. Achromatopsia occurs in only one in every 33, people. People with monochromacy see no color at all. For these individuals, the world exists in black and white, much like an old-time television. The concomitant light sensitivity often transforms everyday tasks into difficult chores. Individuals interested in learning more should visit AchromaCorp. Color blindness is not always inherited.
It can be caused by environmental factors and can affect each eye individually to different degrees. The actual categorizations as outlined above are the same, but the foundational causes are quite different. Some ways color blindness can be acquired are:. Age — A subtle blue-yellow color blindness can develop with age. Quite simply, the lens becomes less transparent, affecting how much light reaches the cones.
Alcohol consumption — Reduced color discrimination can be symptom of alcoholism, with blue-yellow being particularly affected. Brain trauma — Head injury or stroke can sometimes though rarely result in color blindness.
Environmental chemicals — Even at low levels, carbon disulphide and lead can cause color blindness. Most people who become colorblind as opposed to those who are born with the condition retain the ability to perceive some colors, but symptoms may vary over time, and in some cases the condition can progress into more serious types of color blindness, such as monochromatism.
The non-profit Colour Blind Awareness has compiled statistics on types of color blindness the world over. In this article, we will explore what causes color blindness, the different types of color blindness, and what colorblind people see. Humans have three types of light-sensing cones in the eyes: red, blue, and green. With color blindness, also known as color vision deficiency, the pigments in these cones may be dysfunctional or missing. In these cases, the eyes have trouble differentiating between different colors.
This leads to color blindness. Although there are some nongenetic causes of this condition, the primary cause of color blindness is genetics. Color blindness results from an X-linked recessive gene that can pass down from a parent to a child on the X chromosome. Color blindness is, therefore, statistically more likely to affect males , who only need to have one X chromosome with the gene on it to have the condition.
Red-green color blindness is the most common form of the condition. This type of color blindness makes it difficult to differentiate between shades of red and green. There are four types of red-green color blindness:. Blue-yellow color blindness is less common than red-green color blindness, though red-green color blindness often accompanies it. With this type of color blindness, you have trouble differentiating between blue and green, as well as between yellow and red.
Complete color blindness is rare. This type of color blindness, also called achromatopsia, occurs when all the cones of the eye are either dysfunctional or missing. Some experts consider another type of color blindness, blue cone monochromacy, to be a form of achromatopsia since it involves a partial or total lack of color vision.
If you have complete achromatopsia, you have monochromatic vision, which makes everything look like different hues of gray. Having color blindness can make it difficult to perform everyday tasks, especially those that require color differentiation. Some daily activities that color blindness can affect include:. Some people have even benefited from using experimental treatments for their conditions.
Pale pinks with light grey 5. Mid-reds with mid-brown 6. Light blues with lilac. The most common colour confusions for tritanopes are light blues with greys, dark purples with black, mid-greens with blues and oranges with reds.
The images show how the beautiful colours of the pigments are lost to people with each type of dichromatic vision. People with monochromatic vision can see no colour at all and their world consists of different shades of grey ranging from black to white, rather like only seeing the world on an old black and white television set. Achromatopsia is extremely rare, occuring only in approximately 1 person in 33, and its symptoms can make life very difficult.
Usually someone with achromatopsia will need to wear dark glasses inside in normal light conditions. Although we are unable to advise on the diagnosis of specific cases we have undertaken further research to try and understand why so many people are being told they are totally colour blind when in reality they are much more likely to have a severe form of red-green colour blindness.
Our research has revealed that in many cases opticians have only received basic training on colour vision deficiency and some may therefore be incorrectly interpreting the results of the Ishihara tests. If you think you do have the symptoms of achromatopsia ask your optician to refer you to a specialist who can confirm your condition. By contrast in sub-Saharan Africa there are few colour blind people.
Countries such as India and Brazil have a relatively high incidence of colour vision deficients because of the large numbers of people with mixed race genes in their genetic history. To put these statistics in context, an all-boys school in the Home Counties of England with pupils would have approximately colour deficient students.
About half of those with an anomalous condition would have a moderate to severe form of deficiency. Mobile users: We are in the process of updating our website which will create temporary problems for mobile visitors.
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