Giving old eyes a tune-up
For the first time, it may soon be possible to improve or prevent failing eyesight in old age using a combination of simple and painless treatments.
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, says Professor Jonathan Stone of Sydney University and the Australian National University, and the ARC Centre of Excellence in Vision Science (The Vision Centre).
The Vision Centre is reporting significant success in a major collaborative research program which seeks to protect and possibly restore functional vision using simple therapies based on light, diet and oxygen.
These therapies include light management, anti-oxidant dietary supplements, healing of damaged eye cells using near-infra-red light and short-term oxygen therapy, and are all based on a deepening understanding of the cellular and genetic processes within the eye.
Recent research results in animal models show 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 (and affects about 5000 Australians).
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,” Prof Stone says.
A Vision Centre 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,” she says. 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,” Dr Valter says. “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. We have shown that protecting these retinas from light from birth can slow the degeneration. Now we are addressing the question 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, it definitely is. Sunglasses are as important for protecting children as well as young adults from the full sun as a shirt or hat.”
