Vision cells, not brain, to blame for colour blindness

September 21, 2012

The real culprits of colour blindness are vision cells rather than unusual wiring in the eye and brain, recent research has shown.

The discovery brings scientists a step closer to restoring full for people who are colour blind – a condition that affects close to two million Australians, says Professor Paul Martin from The and The University of Sydney.

It may also help pave the way for an answer to one of the most common causes of blindness – age-related macular degeneration (AMD), which accounts for half of the cases in Australia.

"There are millions of cones in our eyes – vision cells that pick up bright light and allow us to see colour," Prof. Martin says. "They are nicknamed red, green and blue cones because they are sensitive to different .

"We now know that in the macular region of the eye, each cone has its own 'private line' into the and the brain. Just as a painter can mix from three tubes of paint to produce a wide and vivid palette, our brain uses the 'private lines' from the three cone types to create thousands of colour sensations.

Scientists previously thought that full colour vision depends on specialised nerve wiring in the eye and brain, but animal studies show that the wiring is identical for monkeys whether they have normal or abnormal colour vision, Prof. Martin says.

"This tells us that there's nothing wrong in the brain – it's only working with the signals that it receives on the 'private lines'," he says. "So the only difference in normal and abnormal colour vision is caused by the first stage of sight, which points to faulty cones. Either they have failed to develop, or else they are picking up abnormal wavelengths.

"Now that we know faulty wiring isn't the cause, we can concentrate on fixing the cones, which are controlled by genes – and thus prone to mutation or mistakes during . There are already promising results from gene therapy as a way to restore full colour vision in colour blind monkeys."

"While we have still have some way to go, the benefits of this gene therapy – if successful – can potentially extend beyond providing complete colour vision," he says.

"If we can get these genes to work in human eyes, it means that the same approach might be possible for other visual problems – including blinding diseases such as macular degeneration."

"In macular degeneration, energy supplies to the macula can't keep up with demand. So the 'private line' system must be very energy-intensive. Gene therapy could be used to turn down the cones' energy demand, or to increase energy supply from supporting cells to cone cells," Prof. Martin says.

"Together with clinical researchers at the Save Sight Institute, we are now working hard to find out exactly how many 'private lines' there are in humans. That can point us to where energy demand is highest and we can target to the right place.

"So animal research on 'private lines' for colour has given new clues for understanding one of the most important visual diseases – macular degeneration – in humans."

Explore further: Scientists unravel the cause of rare genetic disease: Goldman-Favre Syndrome explained

Related Stories

Scientists unravel the cause of rare genetic disease: Goldman-Favre Syndrome explained

August 31, 2011
A new research report published in The FASEB Journal will help ophthalmologists and scientists better understand a rare genetic disease that causes increased susceptibility to blue light, night blindness, and decreased vision ...

Recommended for you

Newly published research provides new insight into how diabetes leads to retinopathy

December 7, 2017
An international team of scientists led by Professor Ingrid Fleming of Goethe University, Frankfurt, Germany, and including Professor Bruce Hammock of the University of California, Davis, provides new insight into the mechanism ...

Researchers use breakthrough technology to understand eclipse eye damage

December 7, 2017
In a first-of-its-kind study, Mount Sinai researchers are using adaptive optics (AO) to analyze retinal eye damage from the August solar eclipse on a cellular level. The research could help doctors develop a deeper understanding ...

Combating eye injuries with a reversible superglue seal

December 6, 2017
When a soldier sustains a traumatic eye injury on the battlefield, any delay in treatment may lead to permanent vision loss. With medical facilities potentially far away and no existing tools to prevent deterioration, medics ...

Trigger for most common form of vision loss discovered

November 27, 2017
In a major step forward in the battle against macular degeneration, the leading cause of vision loss among the elderly, researchers at the University of Virginia School of Medicine have discovered a critical trigger for the ...

Scientists engineer drug delivery device that treats glaucoma directly inside the eye

November 23, 2017
Glaucoma, which affects over 60 million people worldwide, can seem easy to treat: medicated eye drops can be used to ease the buildup of fluid in the eye that underlies the condition. If glaucoma is caught early, eye drops ...

Research reveals biological mechanism of a leading cause of childhood blindness

November 16, 2017
Scientists at the Virginia Tech Carilion Research Institute (VTCRI) have revealed the pathology of cells and structures stricken by optic nerve hypoplasia, a leading cause of childhood blindness in developed nations.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.