Colour blindness (also known as colour vision deficiency), is a condition in which the retinal cone cells respond to light differently than normal. Colour blindness does not mean that someone will see the world in black and white, but will mix up colours or have trouble distinguishing between certain pairs of colours.
Approximately 1 in 12 men and 1 in 200 women have some degree of colour blindness. There are a few types of colour blindness, but the most common one is known as “red-green colorblindness”.
The degree of colour blindness can range from almost normal colour perception to an almost total absence of perception of the colour in question. Colour blindness will occur when one or more of the three types of cones (the red, green and blue) in your eyes do not function properly. The three different conditions are:
- Protanomaly - a reduced sensitivity to red light
- Deuteranomaly - a reduced sensitivity to green light. This is the most common form of colour blindness
- Tritanomaly - a reduced sensitivity to blue light (it is extremely rare)
Protanomaly and deuteranomaly are grouped together and called red-green colour-blind. This leads to difficulty in telling apart reds, greens, browns and oranges, although sometimes will confuse different types of blue and purple tones.
People affected by tritanomaly have difficulty identifying differences between blue and yellow, violet and red and blue and green.