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Colour Blindness


When a person is unable to distinguish between certain colour, he is suffering from a condition known as colour blindness. More men are found to be colour blind than women as the most common form of colour vision deficiency is encoded on ‘X’ sex chromosomes. You will find at least one man with colour blindness in a group of 10 men.

If you are suffering from mild colour blindness, you may lead a fairly normal life, without much complications. However, severe colour blindness can make things like seeing traffic signal difficult. In fact, they should keep away from professions that may require distinguishing or discriminating between colours like a cloth merchandiser, a traffic police or a pilot.

The cones are the photoreceptors which are responsible for our colour vision. They are about 6 to 7 million of cones, gathering together very closely in the centre of the retina.
The various types of colour blindness are:

  • Monochromatism: In this type there is either no cones or only one cone available.
  • Dichromatism: There are only two types of cones available. The third one is completely missing.
  • Anomalous trichromatism: All three types are available, but with shifted peaks of sensitivity for one of them, which results in a smaller colour spectrum. This type is further divided wherein a person is unable to distinguish between the shades of red, green and blue.

The symptoms of colour blindness can range from mild to severe. However, most of them who suffer from this condition show mild symptoms. The common symptoms are:

  • Unable to differentiate between certain colours.
  • Mainly it is difficult to differentiate between green, red and blue.
  • The person suffering from colour blindness cannot distinguish between the shades of same colour.

In most of the cases, someone close notices the condition. The person him/herself is unaware about the condition until someone else tells him/her.

Causes of colour blindness:

  • Considered to be a genetic condition, colour blindness can be inherited. It can either be congenital i.e. right from the birth or can be derived in childhood or adulthood.
  • Colour blindness can also be caused by brain damage, retinal damage or damage to the optic nerve due to accidents, other trauma, disease like diabetes or deficiency of Vitamin A.

Diagnosis of colour blindness is important in cases of children, and electricians, train engineers and pilots whose professions demand importance of colour discrimination. Hence, they have to pass a test for colour blindness to prove that they can easily distinguish between different colours.

Usually, special coloured cards are used in daylight for the test. However, for a more detailed diagnosis,
an instrument called anomaloscope is used. This instrument is designed in a way that it changes its colour in mixture of red and green light. The person taking the test is asked to change the mixture until it looks the same as a yellow light. The final mixture gives the hint to the examiner about the severity of the patient’s condition.

It may be sad to know that the inherited colour blindness cannot be treated. However, if you are suffering from the condition because of damage or an underlying disease, you need to see a doctor. Let your doctor figure out the true cause and treat it.

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