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Causes of Colour Blindness

March 22, 2018 -


Colour Blindness

Sight is one of the wonderful blessings bestowed upon living beings.We perceive the world in shades of various colours. Though seeing looks like a simple involuntary process, the mechanism behind it is quite complex. Some people suffer from an improper perception of colours. This problem is called Colour Blindness.In Below, we could come across some causes of colour blindness and its types.

Colour blindness also is known as colour vision deficiency is the decreased ability to distinguish between various colours. It is a problem that can affect routine activities. It can be hereditary or caused by physical or chemical damage to the eye, optic nerve, or parts of the brain. Colour blindness occurs more often in males than in females.

Types of Colour blindness:

The most common types of colour blindness are inherited. They are the result of defects in the genes that contain the instructions for making the photopigments found in cones. Some defects alter the photo pigment’s sensitivity to colour, for example, it might be slightly more sensitive to deeper red and less sensitive to green. Other defects can result in the total loss of a photopigment. Depending on the type of defect and the cone that is affected problems can arise with red, green, or blue colour vision.

Inherited colour blindness is the result of a genetic defect that controls the photopigments of the cones. It can be partial sensitivity to a few colours or a total loss of colour vision, depending on the type. There are 3 types of light cones in our eyes. The types of colour blindness are based on the functioning and defects of such types of light cones.


People with monochromacy see no colours at all. The accuracy may also be defective. They see the world completely in varying shades of grey.


Out of 3 types of cones, only two types are functional for dichromats. Dichromacy is further classified into:

  • Protanopia: The light cones which perceive the colour red is missing in this type. Red is perceived as black and shades of orange, yellow and green appear as yellow
  • Deuteranopia: The cones which perceive green colour are non-functional when it comes to Deuteranopia. Reds are perceived as brownish yellow and green as beige.
  • Tritanopia: Absence of cone cells that perceive blue colour is called Tritanopia. The blue colour is perceived as green and yellow is perceived as violet or light grey by people affected by this kind of colour blindness. It is an extremely rare condition.


3.Anomalous Trichromacy:

Trichromacy is the ability to see with all the 3 cones and perceiving colours as they are. Anomalous trichromacy is a faulty trichromatic vision. Trichromacy is further classified into:

  • Protanomaly: Abnormality with the cones that perceive red colour is called protanomaly. Shades of red, yellow and orange appear to be shades of green and the colours are not really bright
  • Deuteranomaly: Abnormal functioning of cones that perceive the green colour is called deuteranomaly. Yellow and green colour appear in shades of red. Distinguishing violet from the blue can be a hard task for people with deuteranomaly.
  • Tritanomaly: When cones that perceive blue light function abnormally, it is called tritanomaly. Blue shades tend to appear in shades of green; yellow and red tend to appear in shades pink. This condition is extremely rare.


How Colour Blindness affects daily activities:

Traffic lights may present a confusing problem to people with Colour blindness.Therefore, driving, in essence, becomes difficult for people with this disorder. Cooking also becomes a hard task as the consistency of certain food items is often identified by the change of colours. Similarly, selection of groceries may also be a bit challenging. When it comes to school children, reading from a few textbooks may be hard if they contain colour codes or colour keyed content. If there is a noticeable history of colour blindness in a family, it is better to get children of that family tested, as children are mostly not forthcoming with their problems.

People with colour blindness may have difficulty understanding conversations that involve colours. When someone points out a particular part, describing or criticizing its colour, it may not exactly create the right understanding if a person has colour blindness.


There is no treatment for colour blindness.Though, for people with red-green Colour blindness, special lenses may help their sight under bright lighting.



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