THE GRASS IS GREEN – OR IS IT RED?

This statement by Tim Masters, Art and Culture correspondent for the BBC, points out that colour blindness is not a form of blindness at all, but rather a deficiency in the way one sees colour. There is difficulty distinguishing certain colours, or in the perception of the brightness of certain colours.

What is colour blindness (or colour vision deficiency)?

Colour blindness (or, more accurately, colour vision deficiency) is an inherited condition that affects males more frequently than females. It affects approximately 1 in 12 males, and 1 in 200 females in the world.Most colour blind people are able to see things as clearly as other people, but certain colours appear washed out and are easily confused with other colours, depending on the type of colour vision deficiency they have.

The most common form of this condition is red/green colour blindness. Although known as red/green colour blindness, this does not mean that people mix up only red and green, but that they mix up all colours which have some red or green in them. For example, they may confuse blue and purple because they can’t distinguish the red element in purple. Similar problems can arise across the whole colour spectrum affecting all reds, greens, oranges, browns, purples, pinks and greys.

More rarely, sufferers have a reduced ability to see blue and yellow hues, and this affects males and females equally. It is extremely rare for a colour blind person to be unable to see any colour at all.

The effects of colour blindness on day to day life can be mild, moderate or severe, depending on the form. It has been reported that some people leave school totally unaware that they have a problem with colour perception!

Causes of Colour Blindness

For the vast majority of people with deficient colour vision the condition is genetic and has been inherited from their mother, although some people become colour blind as a result of diseases such as diabetes and multiple sclerosis, or they may acquire the condition over time due to the aging process and medication.

Usually, a mother passes colour vision deficiency down to her son, if she is a carrier of the gene or is colour deficient herself. Her daughter may be a carrier of the gene, and will have colour deficiency only if the gene is passed on to her by both her mother and her father. Fathers with red/green colour blindness may pass the gene to their daughters but not to their sons, in which case the daughters will only be carriers, and not have the deficiency.

How does Colour Blindness Occur?

The retina at the back of the eye has light-sensitive receptors called rods and cones. There are millions more rods than cones, and they are more sensitive to light, but are incapable of perceiving colour. The 6 to 7 million cones, which are concentrated in the central area of the retina, are responsible for colour vision. Colour blindness occurs when the cones fail to respond appropriately to variations in wavelengths of light that enable people to see an array of colours.

Treatment

We live in a predominantly visual world, and colour blindness affects everyday life in different ways for different people. While it cannot be cured, there are certain strategies that can be put in place to help one cope in a colour-oriented world. Most people are able to function effectively by compensating for colour deficiencies and focusing instead on the placement of objects (e.g. in a traffic light), organising and labelling their clothing, distinguishing objects by shape and feel, or making career choices accordingly. However, having said that, a number of artists are colour vision deficient, perhaps the most famous being Vincent Van Gogh.

Learning materials at school rely very heavily on colour perception. It has been suggested that children should be screened for colour blindness as early as possible to make teachers aware of the problem and help them modify activities, to prevent poor performance and embarrassment for children at school.

With new developments in technology, phone and computer apps are being researched that may assist with colour detection.

Consult your optometrist about filters which may be available as contact lenses or glasses, which may enhance colour perception.