Colour vision deficiency


Do you have difficulty telling if something is blue or yellow, and red or green? Do other people sometimes let you know that the colour you think you are seeing is wrong?

If so, these are primary signs of what is called colour vision deficiency, also known as colour blindness.

Colour blindness is not a form of blindness at all, but rather a defect in the way you see colours.

If you are colour-blind, you have difficulty distinguishing certain colours, such as blue from yellow or red from green.

It is an inherited condition that affects males more frequently than females. An estimated 8 percent of males and less than 1 percent of females have colour vision problems(1).

  • Red-green colour deficiency is the most common form of colour blindness
  • Much more rarely, a person may inherit a trait that reduces the ability to see blue and yellow hues. This blue-yellow colour deficiency usually affects men and women equally
colour vision deficiency

Colour blindness is more common than you might think! 1 in 12 men is colour-blind while only 1 in 200 women have the condition. This means that 95% of the colour-blind community are men. 98% of those with colour blindness have red-green colour blindness(2).


What causes colour blindness?

colour vision deficiency ishihara test

Colour blindness happens because of a problem with the pigments in the eye. There are two types of retinal cells, at the very back of the eyeball, which react to light: cones and rods. The cones contain pigments which react to different wavelengths of light. When all the cones have all the correct pigments, vision is fine, but with even one faulty pigment, a person might not see certain colours properly.

Should I see an ophthalmologist?

woman undergoing ishihara coulour test

If you think you suffer from colour vision deficiency, seek the advice of an eye care professional to discuss if colour-blind glasses are a good option for you. If you develop colour vision problems when you have been able to see a full range of colours so far, then you definitely should visit your doctor. 

(2) Wong, Bang. “Color blindness.” Nature Methods, vol. 8, no. 6, 2011, p. 441. Accessed 6 Aug. 2020.