Age Related Macular Degeneration (ARMD)
A challenge for industrialized countries
Definition and Introduction
Age related macular degeneration, or ARMD, is an abnormally rapid and significant ageing of the central part of the eye, which forms the image. This very sensitive area transmits impulses to the brain which are needed to interpret the image. This disease causes the retinal cells, which initiate the transmission of information, to gradually disappear.
This usually begins around the age of 50, but can pass unnoticed for several years. This results in distorted and blurred vision meaning that the patient can no longer distinguish anything in great detail.
There are two forms of ARMD
Dry form (atrophic) – the most common
Wet form (exudative) – the most severe. This is often associated with a severe loss of central bilateral vision due to abnormal blood vessel growth (choroidal neovascularization).
In the most severe cases, visual acuity can decrease to 1/20 or even worse : at which point one is defined as being “legally blind” and thus the patient is eligible to receive social benefits. The patient has the impression that there’s a spot in front of their eye which obscures their field of vision. It prevents them from being able to read and recognize faces and carry out activities where the ability to see details is vital, however, ARMD causes total blindness, peripheral vision remains intact and allows the sufferer to remain independent, helped if needed by visual rehabilitation.
The precise origin of ARMD is not entirely known, but it is considered that there is a genetic link between sufferers. Thus a person is more likely to suffer from it if a member of their family has the same condition.
Age has been identified as another contributing factor to the onset of the condition. The epidemiological study on ARMD indicates that a proportion of the population affected increases with age.
Environmental factors like smoking, cardiovascular problems and diet can all contribute to the acceleration of ARMD.
The magnitude of ARMD
In industrialised countries, ARMD is the most common cause of severe loss of vision. In France, ARMD represent half of all cases in all age groups which is 150,000 people. But almost 1.5 million French people have been affected to some degree by ARMD.
The World Health Organisation estimates that the number of people affected by ARMD will double by 2020 due to ageing global population and the immergence of the disease amongst previously unaffected populations.
It is difficult to detect the illness early. The majority of people are not examined until their vision begins to decrease, and by the time it is diagnosed, the illness has already reached an advanced stage and the diagnosis is based on :
The appearance of the back of the eye
The images of retinal angiography, which allow the identification and localization of abnormal vascular processes. Optical coherence tomography is now used by most ophthalmologists to diagnose ARMD.
The current methods for the prevention and treatment of ARMD are limited. A statistical study (ARES, 2001) composed of numerous patients displayed the benefits of a treatment using antioxidants and vitamin supplements (vitamins A, C, E and zinc). If applied at the very start of the illness, it slows its progression. But at the moment, there is no treatment which has shown to be effective against dry form ARMD (atrophic).
Wet form ARMD (exudative) can benefit from laser photocoagulation treatment either directly or after an intravenous injection which allows the destruction of certain forms of neo-vessels. More recently, anti-VEGF (Vascular endothelial growth factor) has been used ; it is injected into the eye after local anaesthesia. This very expensive medication prevents the proliferation and the development of neo-vessels in the retina. They can improve vision or stabilise the loss of vision, with the condition that the patient is treated as early as possible.
Overall, these treatments can be offered to certain patients, but the long term results are not always satisfactory.
There is currently a lot of research into new products that can prevent and reduce the loss of vision caused by ARMD.
To find out more about ARMD, click here
See : Visual Impairment
In the most severe cases, orthoptic rehabilitation using magnifying optical equipment can often improve everyday life and allow sufferers to remain independent. In the best cases, the person with the visual impairment is able to find a way of reading and writing again.