There are frustrations that go along with being colour blind that are not generally appreciated, writes CIARÁN BRENNAN.
UNTIL FOUR years ago, artist Neil Harbisson painted only in black and white - for a very good reason. He is completely colour blind. For the same reason, he plays only the piano because of its black and white keys.
Harbisson is still colour blind but today he is painting in colour thanks to a revolutionary invention - the eyeborg, a device that enables people with visual impairments, and even total blindness, to experience the world in colour. The eyeborg system hijacks Neil Harbisson's other senses by allowing him to "see" colour through his ears.
Harbisson's condition - complete colour blindness - is a very rare phenomenon, but colour blindness is a much more common condition than most people realise, particularly among men.
The term colour blindness can be very misleading, according to Dennis Overton, a teacher and spokesman for the Colour Blind Awareness and Support Group in Australia.
"The correct term is colour defective vision as some people think we are either blind or do not see any colours at all," says Overton, who has the condition. "We do see colours but not like 'normal' people see. One thing to remember is we are colour blind but not blind to colour."
Colour blindness is the reduced ability to distinguish between certain colours. In all other respects, those suffering can have perfect vision.
"They probably have the same vision as anyone else as far as sharpness is concerned. The acuteness isn't really the issue," says Avril Daly of Fighting Blindness.
It is estimated that 8 per cent of males and less than 1 per cent of females have colour vision problems, although the severity of the condition can vary.
"It tends to affect men more than women," explains Daly. "There is no real reason for it. It is the way it is handed down in the genes. The gene is carried in the X chromosome."
Although defective colour vision may be acquired as a result of another eye disorder, a head injury or disease, the vast majority of colour blind cases are hereditary.
The gene for this is carried in the X chromosome. Since males have an X-Y pairing and females have X-X, colour blindness can occur much more easily in males and is typically passed to them by their mothers.
For a male to be affected, colour blindness only has to appear on his single X chromosome, whereas for a female to inherit colour blindness it must be on both X chromosomes.
Red-green colour blindness - or deuteranopia - is the most common form and is passed down on the X chromosome. People with this condition cannot distinguish certain shades of red and green.
Blue deficiency - or protanopia - is a much more rare condition in which blue and yellow cause problems and are often seen as white or grey.
Colour vision deficiency is most commonly detected with special coloured charts called the Ishihara Test Plates. On each plate is a number composed of coloured dots. While holding the chart under good lighting, the patient is asked to identify the number. Once the colour defect is identified, more detailed colour vision tests may be performed.
There is no known cure for colour blindness at present. "Not until we can come up with some genetic tricks to alter the genes," says Overton.
"There are some tinted glasses on the market that manipulate red and green, and we have had some good and bad comments about them. It may help with the red and green but they do interfere with our perception of the other colours."
Overton says there is a perception that colour blindness is only a minor disability and therefore it does not get enough attention. While not life-threatening in any way, it can have frustrations that are not generally appreciated, he says.
"Our sunrises and sunsets are not interesting, our rainbows are plain, our fruit is not ripe, our meat is not cooked, our clothes do not go together, our paint charts are a blur, our printer/camera batteries are never low," he says. "Bus and train travel route coding and signs are a waste of time. We cannot even see when we are sunburnt."
The problem is compounded by a world in which colour is playing an increasing big part of everyday life, says Alison Daly, whether it is through the use of web pages, colour-coded statistics, maps, timetables, signposting and directions. For example, on a brown background many red and green colours are invisible to a colour blind person. For people with red/green colour blindness, a bright turquoise colour appears almost white.
It can also have an impact on career choice, particularly those where good colour vision is important, including pilots, electricians, train drivers and in the design and fashion industries.
Colour blindness can present particular problems for children, according to Overton.
"Colour plays such an important part of today's early learning process, such as reading and work books. We have contacted many Australian education authorities with regard to the issues. However, it is slow progress."
The key to helping the colour blind is awareness, he says.
"When you are designing signs, information, web pages, directions, bus routes, use the right colours or secondary clues so you can get the information to as many people as possible."