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HealthInfo Canterbury

About macular degeneration

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Macular degenerationLight goes in through the front of our eyes and on to the retina at the back. The retina contains light-sensitive cells and acts like a camera film, capturing the images we see.

The macula is the central part of the retina. It is the most sensitive part, and it allows us to see the fine detail that we need to read, recognise faces and to drive. It is also responsible for most colour vision. The picture shows what eye specialists see when they look through your pupil to the retina at the back.

The rest of the retina lets us see less defined images, and gives us our peripheral, or side, vision, helps us sense movement and helps us see at night.

What is macular degeneration?

Macular degeneration is a disease that affects the cells that feed the retina. Because of the disease, waste products build up and form yellow deposits in the macula part of your retina. These are called drusen. This can start happening without you knowing, as early macular degeneration doesn't always affect your vision. That is why it's a good idea to have regular eye test by an optometrist or eye specialist, as they can tell if this is happening.

The image on the right shows what eye specialists see when they look into the eye of someone with advanced macular degeneration.

Drusen does not always go on to cause vision loss through macular degeneration, but macular degeneration always starts with a build-up of drusen.

There are two types of macular degeneration: dry macular degeneration and wet macular degeneration.

Dry macular degeneration

This is when cells die, leaving patches of missing retina. It progresses slowly and causes a gradual loss of central vision over several years. It accounts for 33% of all cases of advanced macular degeneration. Five to 10% of people who have dry macular degeneration will develop the more aggressive wet form.

Wet macular degeneration

This occurs when blood vessels grow under the retina. These blood vessels are fragile and leak blood, which causes scarring and loss of vision. The loss of vision can be sudden, and needs immediate medical treatment.

What causes macular degeneration?

We think it is caused by genetic and environmental factors working together.

People older than 50 are at risk, and the risk increases with age. It often runs in families. People with a family history of it have a 50% chance of getting it, so it's important to get your eyes tested if your relatives have it.

Smokers have three times the risk of getting it, and they tend to get it 10 years earlier than non-smokers. It's good for everyone to stop smoking, but if you have a family history of macular degeneration and you smoke you are at high risk.

Less common types of inherited macular degeneration can affect children and young adults.

On the next page: How do I know if I have macular degeneration?

Written by Canterbury optometrists. Adapted by HealthInfo clinical advisers. November 2014.


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