Age-related macular degeneration (AMD) is the leading cause of vision loss for people over the age of 50 in the Western world. It occurs when the delicate cells of the macula – the small, central part of the retina responsible for the centre of our field of vision - become damaged and stop working.
There are two types of AMD: the ‘dry’ form and the more severe ‘wet’ form. Dry AMD is the more common, develops gradually over time and usually causes only mild loss of vision. The wet form accounts for only 10-15% of all AMD but the risk of sight loss is much greater. Because macular degeneration is an age-related process it usually involves both eyes, although they may not be affected at the same time.
Children and young people can also suffer from an inherited form of macular degeneration called macular dystrophy, Sometimes several members of a family will suffer from this condition and, if this is the case, it is very important that their eyes are checked regularly.
AMD is not painful and never leads to total blindness because it is only the central vision that is affected. This means that almost everyone with AMD will have enough side (or peripheral) vision to get around and keep their independence.
In the early stages of AMD, central vision may be blurred or distorted and things may look an unusual size or shape. This may happen quickly or develop over several months, although if only one eye is affected it may not be noticed. People with AMD may become sensitive to light or find it harder to distinguish colours. The macula enables people to see fine detail so those with the advanced condition will often notice a blank patch or dark spot in the centre of their sight. This makes activities like reading, writing and recognising faces very difficult.
The cause of AMD is unknown but several factors appear to increase the risk. These include smoking, a high-fat diet and excessive sun exposure. Risk also increases with advancing age and may be more common in those with a family history of AMD. The incidence is higher among women and those with light skin or eye colour.
Optometrists have an important role to play in detecting and monitoring AMD by checking your standard of vision and examining the macula for signs of the disease at routine eye examinations. If AMD is suspected, your optometrist may put drops into the eyes to widen the pupils and see more of the retina. Early detection is essential to treating some types of AMD. Your optometrist will advise you whether you need to be referred to a GP or hospital for medical advice. If your vision is affected, you may be given stronger glasses or special magnifiers to help you see better.
There is currently no treatment for dry AMD but the wet form can be treated in several ways. Various forms of laser treatment may be used to halt or slow the progression of abnormal blood vessels and prevent further sight loss. These are simple procedures that can be carried out on an outpatient basis. Drugs are also becoming available for treating wet AMD, whether in the early or late stages. Trials are also taking place for new types of drugs and for combination therapies using drugs and laser treatment.
There is evidence that improving your diet by eating fresh fruits and dark green, leafy vegetables may delay or reduce the severity of AMD. Some studies show that taking nutritional supplements may be effective in slowing the progression of AMD although they do not prevent its initial development nor improve vision already lost (AMD Alliance).