One in seven Hong Kong people aged 40 and above will develop a degenerative eye disease that already has become the leading cause of blindness in the developed world, an opthalmologist says. Dr Alexis Yu Ka-fai, a consultant opthalmologist at the Hong Kong Adventist Eye Centre, said age-related macular degeneration (AMD) had replaced cataracts and glaucoma as the most common cause of vision loss since advanced treatments and cures rendered the other two less damaging. AMD mars central vision, meaning sufferers may see the periphery well but experience a blur or even blackening in the centre of their field of vision. This effect is caused by the degeneration of the macula, which is close to the optic nerve in the back of the eye. One in 22 sufferers lose their vision. 'Patients cannot read small print, may not be able to recognise the faces of familiar people and the numbers on buses,' Dr Yu said. 'The degeneration is mostly due to ageing, but other risk factors are heavy drinking, smoking, family history, heart disease and high blood pressure.' A survey of 202 people aged 50 and over at the St James Settlement in Wan Chai found that nearly 80 per cent sensed some form of visual deterioration but 72 per cent attributed it simply to ageing. 'Many seniors have the wrong perception that vision deterioration is part of the normal ageing process, whereas in most cases it is the result of an eye disease such as AMD,' Dr Yu said. 'As the majority of them are not aware of the prevalence of AMD and cannot recognise its symptoms, this can mean a delay in treatment which could cause irreversible vision damage.' Dr Yu urged people over 55 to visit an opthalmologist once every year or two. The disease is easy to detect and measures can be taken to prevent progressive degeneration, but there is no complete cure available. A patient who has been living with AMD in both eyes for a year said the centre of her vision was completely blurred, making it difficult to recognise even close relatives and to see at night. 'I used to love reading newspapers and playing mahjong but I can't any more since I developed AMD,' said Ms Chu, 78. Another sufferer, Mr Chow, 87, said the disease had left him fully dependent on his family: 'I can't read the route number on the bus and can't go anywhere unless my daughter-in-law goes with me.' Vitamins A, C, E and zinc were identified recently by the National Eye Institute in the United States as keys to prevention of the disease in a ground-breaking 10-year clinical study, Dr Yu said. The vitamins and zinc can effectively reduce the risk of developing moderate to severe AMD by 25 per cent. The Adventist Eye Centre (telephone 2835 0532) offers a service for people who may want more information about the disease.