On average about 4 per cent of children are affected by Color Vision Deficiency, or colorblindness, but within that average figure boys are color deficient in far greater numbers than girls. This is because the condition is carried through the mother on the X chromosome (females are XX).

A woman who passes the gene on to her children will usually have normal vision. When she has children either her affected X chromosome or her normal X chromosome will be passed on. So, there is only a 50/50 chance the sons of carriers will inherit some form of color vision deficiency. Since males are XY, and the Y chromosome from the boy's father is not involved in passing on the condition, boys are affected much more than girls.

For a girl to inherit colorblindness she must have two affected X chromosomes, one of which will have been passed on by her carrier mother and the other by her father who will have a color deficiency. A mother with color vision deficiency will pass on the condition to all her sons.

The affected X chromosome alters the cone-like nerve cells in the retina at the back of the eye, which enable us to see colors by day and also to discriminate fine detail. Many parents unfamiliar with colorblindness, fear that their child has, as the term implies, a confusion in identifying very strong colors across the whole range of main colors.

This is not the case, however. Two-thirds of children with Color Vision Deficiency will not be severely affected. The chemical within their red and green cones is subject to slight alteration only which causes these children to misidentify pale colors in the main. Strong colors become more of a problem under poor lighting conditions, when they become tired and if they have to name colors under pressure.

Typical of this group of children is the misnaming of pale pink and light green as white, and giving alternative names to secondary shades.

The remaining third of children will have the more severe form where one of the three (red, green and blue) chemicals found in the cone nerve cells is missing. In these instances, very strong primary colors are often confused but still only within a range of ten principal colors. Children with this degree of colorblindness will often draw using an alternative color scheme green hair or brown grass, for example.

Testing your children early for color vision deficiency is important as it helps raise awareness of both parents and teachers to the problems that colorblind children are likely to face at school. It should be pointed out that online tests, while being easily accessible and useful, cannot replace a color vision test conducted by an eye care professional.

Some parents become quite alarmed when their child fails to detect what to them seem obvious numbers, letters and symbols hidden in a circle of dots. Reassuringly, parents should be aware that there is no correspondence between these symbols and the real world.

More reassuringly still, there is a number of strategies parents can employ to instil confidence in their child. With the right sort of encouragement, a child will not view his/her colorblindness as a liability, but simply as a characteristic unique to him/herself.

Here are a few tips which will assist colorblind children gain self-assurance:

Every thing is relative, they say. With a child who has color defects don't be quick to correct color misnaming. Let the family know that the child correctly identifies what he or she perceives, and that everyone accepts these differences in color perception.

Wherever possible use denotative, rather than connotative, attributes to aid color perception. Traffic lights are a good example of the first and caution lights the second. In other words, make color a secondary attribute of the object which should be identified by its pattern, shape texture, etc.

Color Vision Deficiency apart, children have very different ideas than parents when it comes to choosing clothes. Their peers or siblings can often help them avoid glaring color mismatches which they, too, are anxious to avoid.

Teachers should be informed so that they can also employ denotative color codings and modify the tasks they set. Distinguishing colors on diagrams and maps, or putting toys away by color can be a real problem as can peer teasing if the teacher does not lead by example and accept the child's own color perception.

Timely preparation to help the child adjust to restrictions in occupation choice is advisable. There is a long list of occupations where color-critical decisions have to be made and where stringent entry restrictions apply police officers, most pilots, printers, chemists and designers to name but a few.

However, no false ceiling should be placed on a child's aspirations if he or she is one of the 2/3 majority with relatively mild color vision deficiency. Research into potential occupations is advisable when the child starts middle school.

Children with inherited color defects cannot change their perception of the world. It is often parents' and teachers' perceptions of the colorblind child which needs to change.