The clue is, of course, in the name. Age-related macular degeneration (AMD) is an eye disease that affects us as we age. Most people with AMD are in their 80s, but it can affect younger people in their 50s.
AMD affects the retina, the lining covering the back of the eye. The retina contains the macular, an area of tissue that is responsible for central vision. As we age, the cells in the macular are subject to more wear and tear.
This is what causes what Alison McClune, an optometrist and spokeswoman for the Association of Optometrists, describes as a devastating loss of “the detail of your vision”.
“If you have AMD and try to read a book, for example, you’ll be able to see the book, but not the print. Or you could meet someone in the street, but not be able to make out their face.”
AMD has two forms. Dry AMD is caused primarily by wear and tear of the retina, while the wet form of AMD also causes damage to the blood vessels in the retina, making them leakier.
The changeable risk factors for AMD are smoking, high blood pressure, high cholesterol and diet
Wet AMD can be treated with drugs if caught early. But over time the leakiness can lead to scarring and once scar tissue forms, the damage and the effect on your vision is irreversible. At present there is no treatment for dry AMD.
This is why early detection and treatment of wet AMD is crucial. But more important is knowing what puts you at risk and reducing your chances of macular damage, says Winfried Amoaku, associate professor and reader of ophthalmology and visual sciences at the University of Nottingham.
“Essentially AMD happens because of the interplay between genetics and environmental factors,” he says. “The genetic factors you can’t do much about, but research tells us that other risk factors also play an important role – and those you can change.”
“The changeable risk factors for AMD are smoking, high blood pressure, high cholesterol and diet. It’s important that people know that modifying these risk factors can reduce their risk of AMD and can also slow down vision loss if you catch dry AMD early.”
Studies have found that one person in every five with AMD has high blood pressure, while another one in five will have high cholesterol. Smoking trebles your risk of developing AMD and people who smoke on average develop AMD six years earlier than former smokers, and ten years earlier than people who have never smoked.
The AMD Alliance, International, a global charity promoting AMD Awareness Week later this month, recommends a varied diet with plenty of coloured fruits and vegetables, oily fish, such as salmon, tuna or mackerel, and nuts containing omega-3 fatty acids.
There’s also evidence that being overweight – a corollary of a poor diet – is linked with the development of AMD and faster vision loss. There’s also evidence that people who have a high-fat diet also have a higher risk of AMD.
Mr Amoaku recommends his patients take nutritional supplements containing vitamins A, C and E as well as nutrients lutein and zeaxanthin, which can be bought over the counter. He says: “A good diet is essential and a good start, but you won’t do any harm if you are at risk of AMD by taking these kinds of supplements.”