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Giving old eyes a 'tune up' |
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Many older people develop Age-Related Macular Degeneration (AMD) as part of the body's natural aging process. |
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Sunglasses are as important for protecting children and young adults from the full sun as a shirt or hat.
Photo by Phil Scoville.
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With most people now outliving their eyeballs and many going blind in later life, the need to protect or 'tune up' the visual system is becoming acute.
In a major collaborative research program undertaken by the ARC Centre of Excellence in Vision Science (The Vision Centre), significant success is being achieved with a combination of simple therapies that will not only protect - but possibly restore - functional vision.
These therapies include light management, anti-oxidant dietary supplements, near-infra-red light and short-term oxygen therapy. All are based on a deepening understanding of the cellular and genetic processes within the eye.
Recent results in animal models show that these therapies offer great promise for treating vision loss in conditions such as age-related macular degeneration (AMD - the most common cause of blindness in old age), age-related degeneration of the retina and retinitis pigmentosa, which causes permanent blindness in much younger people.
All of the techniques work by manipulating the genetic responses in the eye's vision cells in ways that improve their resilience, boost healing and reduce damage.
"Best of all they are all harmless and easy to use, which means we should be able to achieve high compliance," said researcher, Professor Jonathan Stone from the University of Sydney and Australian National University.
A specialised team, headed by Dr Krisztina Valter, has produced world-first evidence that eyesight damage caused by exposure to very bright light can be repaired or even prevented using doses of near-infra-red light.
"When an eye cell has been damaged by overexposure to light, it usually dies from stress caused by free radicals - but when the cells are stimulated with IR light, they appear to recover significantly and to withstand future damage much better," said Krisztina. The team plans to move to clinical trials shortly.
A second form of treatment is simply to restrict the amount of light entering the eye, using dark glasses or other means.
"We have shown that restricting light in young eyes in animal models of retinal degeneration greatly reduces the amount of damage they sustain from ordinary bright daylight," added Krisztina.
"In some forms of retinal degenerations, vision cells are particularly sensitive to light and become stressed or die from normally non-damaging intensity of light," she explained.
"We have shown that protecting these retinas from light from birth can slow the degeneration. Now we are asking if it is worth limiting light exposure later in life even if the eyes were unprotected during childhood. And the answer, so far, appears to be yes.
"Sunglasses are as important for protecting children and young adults from the full sun as a shirt or hat," said Krisztina.
For younger people suffering retinitis pigmentosa, controlling the amount of light that enters the eye may slow the progression of the disease, or perhaps enable them to save one good eye for when the first has lost all sight, said Jonathan.
In a third development at The Vision Centre, Professor Silvia Bisti of the University of L'Aquila in Italy, has discovered that a dietary supplement of the herb saffron may offer major benefits for protecting and repairing damaged vision.
Saffron appears to work not only as an anti-oxidant but also to regulate genes in the vision cells of the eye, which can improve their resilience and possibly slow down diseases such as retinititis pigmentosa and age-related macular degeneration (AMD).
"We have some encouraging results which suggest it may be possible to reverse the damage of AMD - but it is very early in the research and we will know more later this year," said Silvia.
A fourth development concerns the possible use of oxygen as a short-term therapy to improve vision.
While oxidative damage is a major cause of the loss of our vision cells, it has been observed that saturating the eyes with oxygen for a very short time in a hyperbaric chamber can cause vision to improve.
"For short periods of time oxygen acts as a tonic for the photoreceptors in the eye, but for longer periods it is a toxin," said Jonathan, who is investigating this with the rest of the team.
"The combination of several of these mild treatments may, for the first time, offer a way to restore or prevent failing eyesight in old age. They are all easy and painless to administer, especially the light restriction and dietary approaches which can be applied all through life. We've learned to take care of our teeth, so we still have them in old age - now it's time to do the same for our vision."
The team plans to take the various techniques into clinical trials in Sydney and Rome in the coming year.
* The Vision Centre brings together major research programs from the Australian National University and universities of Queensland, Sydney and Western Australia.
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Many older people develop Age-Related Macular Degeneration (AMD) as part of the body's natural aging process. It is the most common cause of vision loss in Australia and is a degenerative condition affecting the central area of the retina called the macula, which is responsible for fine and reading vision.
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AMD sufferers typically experience a reduction in central vision, leaving the peripheral vision intact.
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Smoking increases the risk of severe visual loss from AMD six fold.
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Retinitis Pigmentosa (RP) is a genetic eye condition that causes the light-sensitive retina, located at the back of the eye, to degenerate slowly and progressively, according to Vision Australia. The first signs may include night-blindness, a narrowing field of vision, light and glare sensitivity.
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Saffron is a spice derived from the dried stigma of the crocus flower and has been treasured for its culinary, medicinal, dyeing and perfuming properties for centuries. By weight, it is worth more than gold.
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The Vision Centre has three research themes: Vision for Living: Eye and Brain, Vision for Action and Robotics, and Vision for Life: The challenge of degenerative diseases - which the 'tune up' story fits into.
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Oxygen therapy, delivered through the nose, is also being investigated in the context of improving poor vision caused by diabetic macular edema; fluid build up in the part of the eye responsible for central vision.
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