Cure for colour blindness on the horizon

Scientists have cured colour blindness in monkeys in a world first.
As well as allowing colour-blind humans to tell red from green, the innovative technique could restore sight to the blind.

Sufferers of age-related macular degeneration – the most common cause of blindness in the elderly – are among the millions who could eventually benefit.

Researcher Jay Neitz said: ‘If we could find a way to do this with complete safety in human eyes, as we did with monkeys, there would be a lot of people who would want it.

‘We hope the technology will be useful in correcting a lot of different vision disorders.’
Professor Neitz used gene therapy – injections of genes – to allow two male squirrel monkeys called Sam and Dalton to see in full colour for the first time.

Like some humans with red-green colour blindness, the monkeys lacked a pigment that the cones – the colour-detector cells at the back of the eye – need to see red and green. As a result, they saw both red and green as shades of grey. Other colours, such as orange, blue and brown appeared washed-out.


To fix their vision, the U.S. scientists injected their eyes with millions of copies of a gene needed to make the missing pigment, the journal Nature reports.

The therapeutic genes contained the necessary DNA code to enable the light-sensing cells to distinguish between red and green – something lacking in the male monkeys.

Tests revealed the gene therapy was a success. The male monkeys now possessed the necessary photopigments to see all colours and were able to correctly pick out red from green on computer image tests.

The monkeys were treated over two years ago and their improvement in colour vision has remained stable since.

Professor Neitz’s team will continue to monitor the animals to evaluate the long-term treatment effects.

They are hopeful that a similar therapy could benefit people who are colour blind.

“This provides a positive outlook for the potential of gene therapy to cure adult vision disorders,” they said.

3 Replies to “Cure for colour blindness on the horizon”

  1. A hi-tech scheme that helped a young boy with a tumour in his skull get speedy treatment is to be rolled out across Scotland, it was announced on Monday.

    The Scottish Government has invested £6.6m in the project, which will see new IT links put in place between high street opticians and hospitals.

    The move will allow optometrists to send images of patients they suspect have serious eye problems directly to specialist doctors in hospitals. The consultant can then decide that day if the person needs a hospital appointment.

    The initiative has already been trialled in Fife, where it helped a 10-year-old boy who went for an eye test and was diagnosed with optic disc swelling.

    He was sent to Edinburgh’s Sick Kids Hospital for an MRI scan within an hour, where he was found to have a tumour in his skull and was operated on.

    Under the old system, the child could have waited weeks for a hospital appointment, leading to his condition worsening.

    It is hoped the new scheme – which should be in place across Scotland within two years – will lead to reduced waiting times and fewer unnecessary hospital appointments.

    Public Health Minister Shona Robison said: “This is fantastic news for patients and optometrists. It means that patients can be seen and treated much more quickly and efficiently.

    “It is also a reminder of how important it is to go for an eye test as they can pick up at an early stage problems that have the potential to become more serious if left untreated.”

    The new scheme was also hailed by eye specialists, with Peter Carson, the chair of Optometry Scotland, describing it as an “excellent outcome” which will result in “enhanced patient care”.

    John Legge, the director of RNIB Scotland, said: “This is a truly superb outcome for the hundreds of thousands of patients attending eyecare services across Scotland every year and consolidates Scotland’s position as the world leader in this field.”

    Meanwhile, Dr John Olson, chair of Eyecare Scotland, said: “This is indeed fantastic news.

    “More importantly, it will enable us to move from a model of two world class, but very separate, services – optometry and the hospital eye service – towards a single, truly integrated, patient-centred national system of eyecare.”

  2. Scientists have successfully translated retinal cone cells, vital for colour vision, into blind mice.

    Four years ago, the same research team transplanted rod cells, used in night vision.

    The hope for restoring vision in the blind is that transplantable cells which mature into rods or cones can be derived from human embryonic stem cells (hESCs), which can grow into any of the body”s tissues.

    “Ultimately, all blindness results from loss of cones,” New Scientist quoted Jane Sowden of University College London, as saying. Sowden”s team extracted cells for transplant from the eyes of fetal or newborn mice.

    They selected cells with activity in a gene called cone rod homeobox which commits cells to becoming rods or cones, reports New Scientist.

    Treatment was given to mice engineered to mimic a form of childhood blindness called Leber”s congenital amaurosis.

    The team injected 200,000 isolated cells into each eye, in a space between the layer of light-sensitive cells – engineered to be damaged in the recipient mice – at the rear of the retina and a supporting epithelial cell layer above.

    Within 21 days, the new cells settled into the photoreceptor layer and grew into rods and cones.

    “This is very exciting work and it would be a huge medical breakthrough to be able to restore lost photoreceptors in patients who are blind,” says Robert Lanza, chief scientific officer at Advanced Cell Technology, a company in Worcester, Massachusetts, which in 2004 successfully turned hESCs into retinal cells.

    “But it”s important to point out that this is very early-stage work, and incorporation of the cells into the retina doesn”t mean that they”re functional, which is of course the ultimate goal.”

    The report has been published in the Journal Human Molecular Genetics.

  3. The NHS is looking into if it should break with convention and recommend the use of an unlicensed treatment for patients at risk of blindness.

    Lucentis is the preferred option for wet age-related macular degeneration – but at £10,000 per patient on average it is a costly therapy.

    However, it is derived from Avastin, a cheaper drug used for bowel cancer.

    The National Institute for Health and Clinical Excellence is now reviewing whether that should be used instead.

    The move, if agreed to, would be unusual, although by no means unprecedented – similar deliberations have been given to transplant drugs.

    The official NHS advisory body normally only considers cases where the drug is licensed for the condition.

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