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Age-related macular degeneration (AMD)

Published by Bupa's health information team, August 2008.

This factsheet is for people with age-related macular degeneration or those who would like information about it.

Age-related macular degeneration (AMD) causes your central vision to deteriorate. It is the most common cause of blindness in the Western world.

About AMD

When light travels through your pupil it is focused onto your retina, which is located at the back of your eye. The retina sends signals to your brain that are interpreted as vision. The macula is a small (about 0.5cm wide) spot in the centre of the retina that processes sharp, clear vision. When you look directly at something, the light is focused on the macula, allowing you to see fine detail and colour.

Illustration showing the different parts of the eye
The different parts of the eye

With AMD, the macula becomes damaged, leading to progressive loss of sight in the centre of your vision.

AMD is common in the Western world. It affects about 20 to 25 million people worldwide. In the UK, around 500,000 people are thought to be affected by AMD. It's the most common cause of sight loss in people over the age of 60.

There are two main types of AMD: wet and dry.

Dry AMD

Dry AMD is the most common type of the condition. Nine out of 10 people who develop AMD develop dry AMD. In dry AMD, the cells in the macula gradually get worse, usually causing a deterioration of central vision over the course of five to 10 years, although it can be slower than this in many people.

Wet AMD

Wet AMD happens when blood vessels start to grow behind the retina. These can leak and cause scarring, damaging the macula. It can lead to a more rapid and severe loss of central vision than dry AMD.

Symptoms

AMD usually affects both eyes; however it may affect one eye some time before the other. At first, this may not be obvious as the good eye can mask the deterioration in the other one.

The symptoms of AMD can progress slowly over the course of months, but sometimes they develop more quickly. Symptoms include:

AMD affects the centre of your vision; your peripheral vision - what you can see to the sides - isn't generally affected. As it develops, activities such as reading, recognising people's faces, driving, looking at small objects and watching television become progressively more difficult. However, AMD is not a painful condition, and it almost never causes complete blindness.

Causes

No one knows exactly what causes AMD. However, there are a number of factors that can make AMD more likely.

Diagnosis

AMD is sometimes detected during routine eye tests by your optometrist. He or she will check your level of vision and examine your macula using instruments to look inside your eye. He or she might use eye drops that make your pupils widen (dilate) so that it is easier to examine your macula.

If AMD is suspected he or she will advise you to see your GP, or you may be referred to an ophthalmologist (a doctor who specialises in identifying and treating eye conditions).

Some other tests you might have are listed below.

Treatment

Dry AMD

Currently there is no cure for dry AMD. The best treatment that can be offered is the use of visual aids such as advanced magnifying glasses and reading lights which will make the best use of your vision. Computers can be set up to read out text which is difficult to see or to display large text. Voice to text software can help drafting documents and email.

Studies have shown that the use of specific vitamin supplements help some people to reduce the rate the condition progresses, and these will be available from your eye specialist.

Researchers are continuing to investigate ways of treating dry AMD.

Wet AMD

There are some treatment options for wet AMD listed below.

Photodynamic therapy (PDT)

PDT doesn't restore vision, but it can help stop wet AMD from getting worse. A special light-sensitive dye is injected into your arm, which then travels to the retina. A low-power laser is then focused on the macular area of the retina, destroying the abnormal blood vessels, without affecting the surrounding tissue.

The treatment may need to be repeated every three months if the blood vessels behind the retina continue to bleed.

Laser treatment

Like PDT, laser treatment isn't a cure for wet AMD, but it can sometimes limit its progress. This is only effective in about one in 10 people with wet AMD. A laser is focused on the macula through a special contact lens. Heat from the laser destroys the blood vessels causing the AMD.

There is a risk that surrounding macular tissue is damaged in this procedure. Laser treatment has limited benefit and needs to be carried out early on in the course of the disease to be effective. Laser treatment is rarely used now. It has mostly been replaced by PDT, which carries less risk of damaging macular tissue.

Medicines

Certain drugs, known as Anti-VEGF factors, are a class of medicines originally developed to treat cancer. They work by stopping new blood vessels growing.

Injecting anti-VEGF medicines into the eye is fast becoming the standard method of treating wet AMD. It has been shown to be effective at preventing wet AMD from progressing in many cases. In some patients they have even helped restore some lost vision.

However, these treatments are only thought to be effective if they are used during the early stages of the disease, so early detection and rapid referral is essential.

Some anti-VEGF medicines are licensed for treating AMD while others aren't.Your ophthalmologist will be able to provide more information on which treatment is right for you.

Prevention

You can help reduce your chances of developing AMD by not smoking, wearing sunglasses, and eating a balanced diet with plenty of fruit and veg.

Having regular eye tests is important because they can pick up eye conditions such as AMD early when treatment may be more useful. Adults should have an eye examination every two years.

Further information

Sources

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr James Quekett BSc MB ChB MRCGP DRCOG DFFP, and by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: August 2008.