Age-related macular degeneration (AMD) is caused by a problem with part of the eye called the macula. The macula is the spot at the centre of your retina (the nerve tissue lining the back of your eye).

The macula is the part of your eye where incoming rays of light are focused. The macula plays an essential role in helping you see things directly in front of you and is used for close, detailed activities, such as reading and writing. 

Dry age-related macular degeneration

As you get older, the layer of tissue underneath your retina can start to thicken. This means your retina can no longer exchange nutrients and waste products as efficiently as it used to.

Waste products start to build up in your retina and form small deposits, known as drusens. A build-up of drusen, combined with a lack of nutrients, causes the light cells in your macula to become damaged and stop working.

If the light cells in your macula are damaged, your central vision will become blurry and less well-defined.

Wet age-related macular degeneration

In cases of wet AMD, tiny new blood vessels begin to grow underneath the macula.

It is thought these blood vessels form as a misguided attempt by the body to clear away the waste products from the retina.

Unfortunately the blood vessels form in the wrong place and actually cause more harm than good. They can leak blood and fluid into the eye, which can cause scarring and damage to your macula.

This then causes the more serious symptoms of wet AMD to develop, such as visual distortion and blind spots.

Increased risk

Exactly what triggers the processes that lead to AMD is unclear, but a number of things are known to increase the risk factors of developing it. These are described below.

Age

The older a person gets, the more likely they are to develop at least some degree of AMD.

Most cases start developing in people aged 50 or over and then rise sharply with age. It is estimated that one in every 10 people over 65 have some signs of AMD.

Family history

Cases of AMD have been known to run in families. If your parents or siblings develop AMD, it is thought that your risk of getting it is increased.

This would suggest certain genes you inherit from your parents may increase your risk of AMD. But exactly which genes are involved and how they are passed through families is unclear.

Smoking

Smoking is a significant risk factor for AMD. In general, people who smoke are up to four times more likely to develop AMD than those who have never smoked.

The longer you have been smoking, the greater the risk. People who smoke and who also have a family history of AMD have an even greater risk.

Gender

Women are more likely to develop AMD than men, but this could simply be because women tend to live longer than men.

Ethnicity

Studies have found rates of AMD are highest in white and Chinese people, and lower in black people. This again could be the results of genetics.

Possible risk factors

A number of other factors that may increase your risk of developing AMD have also been identified, but a link with the condition has not yet been proven.

Alcohol

It is possible that drinking more than four units of alcohol a day over the course of many years may increase your risk of having early AMD. One unit of alcohol is approximately half a pint of standard beer or lager, or one 25ml serving of spirits.

Sunlight

If you are exposed to lots of sunlight during your lifetime, your risk of developing macular degeneration may be increased. To protect yourself, you should wear UV-absorbing sunglasses if you are outside for a long time in bright sunlight.

Obesity

Some studies have reported that being obese – having a body mass index (BMI) of 30 or greater – may increase your chance of developing AMD.

High blood pressure and heart disease

There is some limited evidence that having a history of high blood pressure or coronary heart disease may increase your risk of developing AMD.

Macula

The macula is a small spot at the centre of the retina. It is the part of your eye where incoming rays of light are focused.

Retina

The retina is the nerve tissue lining the back of the eye. It senses light and colour and sends it to the brain as electrical impulses.