Fact sheet: Age-related macular degeneration

It is a normal part of ageing: with the years, our sight slowly gets weaker. But for some people, it is worse than that and they develop eye disease. One of the problems that can cause vision loss is so-called macular degeneration. It is the most common cause of sight loss in industrialised countries. There is no cure for this condition. For some people it is possible to slow down its progress.

How does the eye work?

The eye works a bit like a camera. The pupils help control how much light gets into the eye. How wide open the pupil is changes in response to light coming through the iris (the coloured part of the eye). It works like the shutter or diaphragm of the camera. The light then reaches the lens, which focuses it onto the retina. There are about 125 million light-sensitive cells in the retina. The retina sends messages along the optic nerve to the brain.


Some of the cells in the retina, called cones, are responsible for seeing colours, and the others, called rods, see black and white. But the rods and cones are not spread equally around the retina. The cones that see colour are thickest in the middle of the retina. This is a yellow spot called the macula. This is also the part of the eye that helps us see fine details. What we see with the macula is what we can concentrate most closely on.

What is macular degeneration and what causes it?

There are so many sensory cells packed into such a small space in the macula, that it is no easy task for the body to remove the by-products of metabolism. It is quite common then for these to build up into little spots called drusen. This is called maculopathy. This condition is not noticeable at first. If it progresses, though, it can start to harm the retina. Then it is possible to detect vision problems in an eye examination. Once there are problems with the vision, the condition is called age-related macular degeneration (AMD).

AMD leads to a loss of the sharpest most detailed part of our sight. The things that we want to look at closely get blurry or distorted. This is called our central vision. Central vision is important for things like reading, driving and recognising faces. You can still see more clearly around the edges of what we are looking at though.

We do not know exactly what causes AMD. Studies show that it happens to people in some families when they are still young, while in other families it does not happen even when people are much older. If a close relative already has AMD, your own risk is higher. It is also known that it happens to smokers more often and earlier than to non-smokers.

Some research suggests that AMD is the result of the very intensive metabolism activity that happens in the sensory cells of the retina. This needs a lot of oxygen. Using oxygen, though, results in a lot of so-called free radicals. Free radicals in the tissues do a bit of harm. Light encourages that process too. It is possible that for some people the ability to repair this damage cannot keep up.

This theory has not yet given us any concrete actions that can definitely prevent AMD. One of the common recommendations is to take anti-oxidant vitamins, like beta-carotene (a building block of vitamin A) and vitamin E. These vitamins, along with other dietary supplements like zinc, omega-3 fatty acids and ginkgo biloba, are all being tested by researchers to see if they might prevent AMD. But none has yet been proven to definitely work.

There are two types of AMD. About 8 out of 10 people have the type called 'dry' AMD. The other 2 out of 10 people with the condition have what is called 'wet' AMD. Drusen are the sign that someone has dry AMD. New blood vessels growing in the retina are the cause of wet AMD. This is also called neovascular AMD. If blood or fluids leak out of these vessels, it can cause damage to the retina.

What are the treatment options for AMD?

There are no treatments that have been proven to be effective for dry AMD. For people who have wet AMD there is photodynamic therapy. As long as the loss of vision has not gone too far, this treatment can slow down the progress of the condition for some people. In Germany, the costs of photodynamic therapy for people with wet AMD are covered by health insurance.

Photodynamic therapy is done every three or four months. A medicine called verteporfin reacts to light. It is injected into the veins. Then a laser is used to send a microscopic beam of light through the eye's lens. When the light from the laser reaches the medicine in the blood vessels, it reacts to destroy the unwanted blood vessels. The dose needs to be at a level that ensures the retina itself is not damaged.

Using the results of trials of photodynamic therapy, it is possible to estimate that in two years, without treatment, 64 out of every 100 people with wet AMD would have a noticeable loss of vision. But for people who had five sessions of photodynamic therapy over those two years, sight was worse in 50. Put another way: about 14 out of every 100 people (14%) benefited from the treatment. And this difference could still be seen after four years. But photodynamic therapy cannot repair damage that has already happened in the retina.

The therapy does have side effects, though. It causes new sight problems in 1 to 5 out of every 100 people (5%). About 5 out of every 100 people (5%) have temporary back pain. And because sunlight can also activate the medicine in the skin, people to need to avoid direct sunlight for several days after treatment.

There are other forms of laser treatment, but these have not been as well studied as photodynamic therapy. A new drug called pegaptanib is becoming available for people with wet AMD in many countries. This is injected into the eye every six weeks. The advantages and disadvantages of this drug are currently being carefully analysed by international researchers. Other treatment options, including drugs, radiotherapy and implants are in the experimental phase.

Are there any other ways to protect our sight?

Although it is not yet known whether or not vitamin supplements can help prevent AMD, there are several other actions that might help to protect sight. People with diabetes are at higher risk of eye problems, but the risk can be lowered with good blood glucose control and early treatment of diabetes-related eye problems.

Computer screens do not harm the eyes. While lots of reading and time at the computer might cause eye strain and headaches, it will not damage eyesight.

© IQWiG (Institute for Quality and Efficiency in Health Care)