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Colour Blindness: Finding the Full Spectrum

Everything we read is awash with colour and movement – maps, brochures, web pages, iPads, signage, retail shelves and cinema screens – everything. It’s highly stimulating for most of us but for the one million Australians and 200 million people worldwide who are colour blind, it can be frustrating, confusing… even dangerous. New research into the condition of colour blindness could eventually make this a problem of the past.

Researchers at the University of Washington have worked with squirrel monkeys to identify the missing visual pigment gene that leads to the condition of colour blindness. Importantly, they’ve found a way to overcome the problem and in doing so, restore full sight.

The missing gene called L-opsin is crucial when it comes to distinguishing reds from greens. While female squirrel monkeys are well endowed with L-opsin, none of the males of the species is lucky enough to have it.

Until now.

By stimulating highly realistic colour blindness, the filters make it possible to find problematic colour schemes in almost any situation

Having surmised that the female version of L-opsin could enable the males of the species to see the full colour spectrum, the researchers identified a harmless virus that could transport the missing pigment gene to the back of the retinas.

They trained two adult male squirrel monkeys nicknamed Dalton and Sam, to recognise specific patterns of blue and yellow dots against a grey screen then introduced the gene.

While the effects were not immediate, five months later the

duo began to pay attention to patterns of green and red dots used to test their vision. The scientists concluded that the squirrel monkeys were able to see the full colour spectrum. Two years on, the monkeys have experienced no further changes in their vision and no noticeable side effects.

Universal Colour Codes

It’s all great news for the future of people who suffer from colour blindness but in the meantime, 200 million people worldwide need help to manage every day tasks. As a population, we rely on our ability to differentiate colour. If we can’t do that, we have to ask for help, or find other differences that may be more difficult to pick – or rely on.

For this reason, scientists in Japan have been working to develop a universal system of colours to ensure that people with colour blindness have a clear picture of what they’re seeing and doing.

Colour Universal Design (CUD) is intended to become a universal colour code that people with colour blindness can rely upon. However, the development of the system has been difficult because people with normal vision, who are not colour blind, do not have an intuitive understanding of the difficulties posed by colour blindness.

Unique Colour Filter Glasses

With this in mind, in 2007 Shigeki Nakauchi, a scientist at Japan’s University of Technology created unique colour filterglasses that replicate colour blindness. The filter, which is marketed as ‘Variantor’ eye glasses and ‘Pancake’ glass loupes, modifies the optical spectrum to reproduce colour blind characteristics. By stimulating highly realistic colour blindness, the filters make it possible to find problematic colour schemes in almost any situation. As a result, the filter is now being widely used for colour combination tests in industry and in public facilities for printing material, public signs, and textbooks.

In recognition of this important development, Shigeki Nakauchi has been awarded the 2011 Award for Science and Technology (Development Category) by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) for the ‘Development of a filter to understand what the world looks like to colour deficient people for use in Colour Universal Design (CUD)’. Masashi Yamaguchi, from the International Affairs Division at Toyohashi University of Technology told mivision that the prestigious award is only given in recognition of inventions three years after their release to the market. The winning invention must be widely used in society and must improve the everyday lives and socio-economic conditions of people worldwide. While colour filter-glasses are doing just that, researchers hope the procedure developed to cure squirrel monkeys of colour blindness can one day be used on people – and eventually make Shigeki Nakauchi’s innovation obsolete.

A Congenital Disease

Colour blindness is mainly a congenital disease caused by corrupted chromosomes. Interestingly, it was the trigger that started scientists mapping the human genome. Scientists, who observed that full coloursighted mothers passed colour blindness on to their sons, determined that red-green colour blindness must therefore be assigned to the X sex chromosone. That was back in 1911.

Since then, researchers have discovered that the corrupt chromosome affects one of the three different cone cells behind the retina. These cone cells react to light, help see detail and pick up red, green and blue light respectively. Each type of cone is tuned to perceive predominantly long wavelengths, which are reddish, middle wavelengths (greenish), or short wavelengths (bluish). By combining the messages from each set of cone cells, full sighted people get a wide range of colours. A person who is red-green colour blind lacks one or more of these types of cone cells.

While red green colour blindness is directly linked to the sex chromosome, about five per cent of colour blind people have blue colour blindness. Blue colour blindness is equal in males and females, because the genes for it are located on a different chromosome. This condition is not always inherited – it can be due to a change in the chromosome during development or over a person’s life. “The researchers identified a harmless virus that could transport the missing pigment gene to the back of the retinas”