What is it?
As the name suggests, age-related macular degeneration (ARMD) is a condition which tends to become more common as people get older. It is a very common cause of reduced vision in Ireland but it never leads to complete blindness as only the central part of the vision is affected and not the side vision.
What causes it?
The retina at the back of the eye transmits the images or messages that we see to the brain. The retina is made up of two parts – the macula and the peripheral retina. The part of the retina responsible for seeing fine detail such as reading, interpreting different colours and making out facial features and shapes, is the macula. The macula which is affected in age-related macular degeneration.
How does it develop?
The macula is the one part of the eye, which has to work extremely hard throughout its lifetime to interpret fine detail, and it is this constant ‘wear and tear’ which causes it to deteriorate as the aging process takes place. There is some evidence to suggest that waste materials from the very active macula build up over a period of time as the mechanisms for removing them slow down with the aging process. This, in turn, causes damage to the cells.
Who is at risk?
Age-related macular degeneration usually affects the 60+ age group and is more common among women than men. Some younger people, particularly those who are very short-sighted, may also be at risk.
There are ongoing studies looking at the links between genetic inheritance (although it is hard to find the parents or grandparents of people in their 60s), light exposure, diet and smoking with the onset of AMD.
What are the symptoms?
There are two distinct types of ARMD, wet and dry, and the symptoms are as follows:
Wet ARMD:
Wet ARMD is due to the abnormal growth of blood vessels beneath the macula and their leakage. Vision will be distorted to the extent where straight lines will appear curved or tilted. This is referred to as metamorphosia. Eventually, the vision will become so distorted that the patient will be left with only a dark central area of very poor vision (known as a central scotoma).
Dry ARMD:
Dry ARMD is due to the build up of natural waste products from the retinal cells. This is a gradual process where the central vision is reduced over a period of time. It affects the ability to read and to make out other fine detail more than it affects distance vision.
Is there any treatment?
Neither tablets or eye drops are effective in the treatment of ARMD. Treatment for the dry form of the condition usually involves wearing good spectacles, particularly for fine work like reading, writing etc and perhaps using bright lights to help the patient to make out fine detail more clearly.
Some people suffering from wet ARMD may be suitable for laser treatment, but this is only successful if the condition is diagnosed in its early stages. To determine whether patients will benefit from laser treatment, an investigation called a Fluorescein Angiogram is carried out. During this procedure a dye is injected into a vein in the arm and this enables a series of photographs to be taken of the back of the eye. If this shows that a lesion is treatment, laser treatment will be performed at the earliest possible opportunity.
However, laser treatment for wet ARMD carries risks, one of which is that the lesion may continue to progress despite the treatment. Another is that the vision may deteriorate as a result of laser treatment being applied.
Does ARMD lead to blindness?
While there may be a significant reduction in vision as a result of ARMD, it does not lead to complete blindness. Because the peripheral (or side) vision is never affected, most patients can continue to remain mobile and to lead an independent existence. However, ARMD patients can be registered as being partially blind on the recommendation of their ophthalmologist, and can therefore quality for certain State benefits.
Can it be avoided?
Since it is an age-related condition, there is little that any of us can do to avoid the risk of developing ARMD (except to avoid old age itself!). However, it is a wise precaution for everyone in the 40+ age group to undergo a thorough eye check-up at least once a year. This advice particularly applies to those who are aged 60 years and over, which is the high-risk category for age-related macular degeneration.
Recent studies have suggested that certain dietary supplements may delay the onset of AMD. However, you should always consult a doctor before taking any supplements.