Macular degeneration und photodynamic therapy

The light rays bundled by the cornea and the lens are focussed at the rear of the eye on the retina. The macula or yellow spot is the point of maximum visual acuity. It accounts for only around 2 per cent of the area of the retina. The other 98 per cent of the retina allows spatial orientation by means of the visual field perception.
Age-related macular degeneration (ARMD or AMD) is the most frequent retina disorder and can have a serious impact on sight. AMD leads to the decline of the sensory cells at the point of maximum visual acuity of the retina. Affected persons can no longer read or recognise faces and are severely restricted in their everyday lives. In Germany more than one million people are affected and thousands more are added every year. The disease usually occurs after the age of 50. One quarter of people over 75 in Germany suffer from this disorder.

Treatment is available today for certain forms of the disease. These are only effective however, if therapy begins early, so early detection is extremely important. Completely new therapy approaches are currently being developed which give rise to hopes for the future.

There are two forms of AMD: dry-type and wet-type macular degeneration.

The two forms of AMD differ in the course of the disease. In the dry form of AMD, vision declines gradually. This is the most frequent type of AMD and accounts for 85 % of cases. As a result of metabolic deposits, the so-called druses, optic cells are killed off slowly, resulting in a gradual loss of focus.

Wet-type AMD is characterised by a more rapid loss of vision. Abnormal blood vessels grow from the choroid into the area of the macula. Fluid escapes from these porous vessels into the retina leading to a swelling of the tissue. This in turn causes a distortion of the image projected onto the retina. The fluid increasingly lifts the retina from the choroid thus causing an increasing decline in vision.

The first indications of macular degeneration are optic distortions: straight lines are perceived as wavy or misshapen and faces are no longer recognised. Sufferers also report "foggy" or "blurred" vision. Signs which cannot be made out in the distance can be an initial indication of macular degeneration. Gradually the ability to focus declines, fixed objects become less and less focussed. Finally the sufferer perceives a large dark spot at the centre of his or her field of vision. If such symptoms occur, a doctor should be consulted immediately.

New form of treatment: Photodynamic therapy

As yet we do not have any way of treating the causes of dry AMD. The main therapy recommendation so far is an active and healthy lifestyle. This includes activation of the circulation, giving up smoking and a healthy, vitamin-rich diet.

In the case of the wet form of AMD, some patients respond well to a new form of treatment known as photodynamic therapy (PDT). To carry out PDT a medicament is first injected into the vein of the arm. This is deposited in the pathological neovascularisation around the macula and is activated by low-energy laser in the eye. The activated medicament destroys the newly formed abnormal vessels. If this treatment is carried out for wet AMD, regular check-ups are necessary to ensure that any new growth of abnormal vessels is detected early so that the treatment can be repeated as necessary.
Unfortunately, even photodynamic therapy cannot actually cure macular degeneration. It is usually only possible to prevent any deterioration or slow it down. If therapy is not possible, the only option is to provide suitable aids such as magnifying glasses and spectacles. The aim here is to use the healthy retina around the affected retina centre more efficiently in order to allow the sufferer to read.