Colour blindness is a condition which usually described as a deficiency which hinders the sufferer from differentiating between colours that the general population can distinguish. The gene that causes it id dominant in males and it is rarely a developed condition. Females are only susceptible to colour blindness if both mother and father are a carrier of the gene. In the UK it effects between seven and eleven per cent of males although statistics are not wholly clear as many sufferers of colour blindness are never diagnosed.
An optician can make a diagnosis for it with a series of simple tests. As a rule, opticians will carry out colour blindness tests as a matter of routine when carrying out sight test on children. Adults would probably need to ask for a test to be carried out as tests for it are not usually included as pert of routine eye tests for those past teenage years.
The most common deficiency found in those that suffer from colour blindness is the inability to differentiate between the colours green and red. A more rare form is an inability to clearly define the colour blue; this is apparent in less that 5% of it sufferers and can be found just as often in females as it is in males.
The test used to test for signs of it was developed in 1917 by Dr. Shinobu Ishihara. The Ishihara test consists of a series of plates each of which incorporate an image of seemingly randomly placed dots of varying size and shades. A person with normal colour vision would be able to see a number within the image, which would be in a contrasting shade to the background. Someone who suffers from it would either not be able to see the number at all or would have difficulty in spotting amongst the other coloured dots. There are thirty-eight plates, or images, which are used in the test, each varying in difficulty.
For pre school children it was deemed that the test was not sufficient as in order to make a diagnosis, opticians would need to be sure that the child knew their numbers competently enough to be able to get an accurate reading. A test was developed for children ages three to six that is consistent with the original Ishihara Colour Test but uses easily recognisable images shapes like stars, circles and squares to determine whether the child is able to differentiate between colours.
Anyone who suspects that their child or themselves is suffering from it should make an appointment with an optician to go through a quick and easy series of tests. Although there is no treatment for it, changes can be made to make life easier for sufferers. Printing on paper that is not white or changing the settings on a computer monitor can make small tasks that used to be difficult a whole lot easier.