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'Twinkle' test hope for AMD

An eye

A new test may help people spot age-related macular disease (AMD) earlier

British scientists have developed a new test for age-related macular disease (AMD), the most common cause of blindness in the UK. Scientists are hoping the 'twinkle' test will lead to earlier self-diagnosis of the problem. At the moment, self help tests are unreliable so many patients delay seeking medical help, which can result in unnecessary loss of vision.

The new test, developed by a team at UCL (University College London), relies on a visual illusion known as the ‘twinkle after-effect’. The scientists have developed a way of creating a moving pattern in the region of the eye where there is vision loss. This ‘twinkle’ test has already been shown to work on healthy eyes where vision loss is artificially induced but this is the first time it has been shown to work on people with AMD.

"At present, people identified as being at risk of AMD are given a grid chart to observe on a daily basis. However, as many as 1 in 2 people will not be able to detect their vision loss using this chart, as the brain ‘fills-in’ the missing information," said researcher Michael Crossland, from the UCL institute of Ophthalmology, "The initial data on our test indicates that it is quick, accurate and resistant to the effects of filling-in."

AMD is the most common cause of severe sight problems in the UK and generally affects older people. About one in 100 people aged 65-75 have AMD severe enough to cause serious visual impairment. The condition is caused by the degeneration of cells in a part of the eye called the macula, a vital part of the retina at the back of the eye. The disease causes the loss of central vision, which affects tasks like reading, writing or driving.

There are two types of AMD, wet and dry. Dry-AMD accounts for 90 per cent of all cases and tends to be less serious. Wet AMD, however is likely to cause severe visual loss over quite a short time. Recent advances in the treatment of have meant that many people with wet-AMD can retain their vision if they start treatment early.

A group of drugs called anti-VEGF (Vascular Endothelial Growth Factor) are injected directly into the eye preventing the formation of abnormal blood vessels that cause the damage.

"Our aim is that we can adapt this system so that people can have a simple test to check their vision at home," says co-author Dr Peter Bex from Harvard Medical School. However he cautions against becoming complacent,

"Obviously these advances will take some time, so for now the best thing people can do is ensure they check their vision regularly by the means advised by their specialist."

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