What is colour vision deficiency?

Colour vision deficiency (CVD) or colour blindness is when the eyes are unable to detect certain colours. People with colour vision deficiency find it difficult to tell differences between colours. How difficult this might be for someone depends on the severity of the colour vision deficiency.

Cone cells are concentrated in the centre of our retina, called the macula where the light is focused by the cornea and lens. Cone cells give us our detailed vision which we use when reading, watching TV, sewing and looking at people's faces. They are also responsible for most of our colour vision.

CVD is caused when there is a problem with the cone cells. The visible spectrum is the range of colours and wavelengths that the eye can see. There are three types of cone cells which detect a range of different colours or wavelengths of light:

  • Red cone cells detect long wavelengths of light
  • Green cone cells detect medium wavelengths of light
  • Blue cone cells detect short wavelengths of light

CVD is most commonly genetic or inherited (meaning you are born with it). Inherited CVD does not improve or get worse with age. Most forms of inherited CVD do not affect the eye’s ability to see fine detail.

CVD can develop (be acquired) as the result of:

  • an underlying eye or health condition, such as optic neuritis from multiple sclerosis, or diabetes
  • a side effect of a medication
  • exposure to harmful chemicals
  • the ageing process

Depending on the cause, acquired CVD can vary, improve or get worse with time. When the cause is known, you may be able to get a better understanding of how it might change with time.

Please also see What types of colour vision deficiency are there?

Did this answer your question?

Related questions

Brought to you by