Age-related macular degeneration: What can photodynamic therapy do?

Photodynamic therapy can slow down vision loss for some people with age-related macular degeneration, but it cannot restore lost vision.

The macula is the central part of the retina, and it is responsible for fine detail in our vision. This is because there are so many light-sensitive cells in this area of the eye. As we age, some of these cells die and leave scarring. If this loss of cells goes too far, our vision will be impaired. This condition is called age-related macular degeneration (AMD) and it is the most common cause of vision loss in people over 65 in developed countries.

There are two forms of AMD. About 8 out of 10 people have so-called dry AMD and the others (about 2 out of 10) have wet AMD. With wet AMD, new blood vessels develop in the retina and these can leak blood and fluid into the eye. This kind of AMD is also called neovascular AMD. You can read more about AMD in our Fact Sheet (URL: index.165.207.en.html).

There is as yet no effective treatment for dry AMD. Photodynamic therapy is a treatment option, though, for some people with wet AMD. This treatment is done every three or four months. It involves an injection of a light-sensitive medicine called verteporfin, which spreads through the body's blood circulation system. 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.

In order to weigh up the pros and cons of this treatment, researchers from the Cochrane Collaboration found and systematically analysed trials of photodynamic therapy. They found two trials involving almost 1,000 people with neovascular (wet) AMD. Both the trials were sponsored by the product's manufacturers.

These trials provide some evidence that regular photodynamic therapy can slow down the progress of vision loss for some people. From the trials 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.

The trials also provide some information about adverse effects. For about 2 out of every 100 people in the trials, photodynamic therapy caused new sight problems. About 3 out of every 100 people (3%) complained of temporary backache. Because sunlight can also activate the medicine in the skin, people need to avoid direct sunlight for several days after treatment. Some people who have photodynamic therapy experience sunburn.

The trials also show that this therapy cannot reverse vision loss that has already happened. According to the researchers, this means that photodynamic therapy is more suitable for earlier AMD, when there has not been a lot of damage to the sight. In Germany, the costs of photodynamic therapy for people with wet AMD are covered by health insurance.