Age Related Macular Degeneration (ARMD)
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Age-related macular degeneration (ARMD) is the most common cause of vision loss in those over 50s and its prevalence increases with age. It is caused by degeneration of the macula, the central, and most sensitive part of the retina at the back of the eye.
The macula is the part of the retina that allows the eye to see fine details at the center of the field of vision. Degeneration results from a partial breakdown of the retinal pigment epithelium (RPE).
The RPE is the insulating layer between the retina and the choroid (the layer of blood vessels behind the retina). The RPE acts as a selective filter to determine what nutrients reach the retina from the choroid. Many components of blood are harmful to the retina and are kept away from the retina by normal RPE.
Breakdown of the RPE interferes with the metabolism of the retina, causing thinning of the retina (the “dry” phase of macular degeneration). These harmful elements may also promote new blood vessel formation and fluid leakage (the “wet” phase of macular degeneration).
This disorder results in the loss of central vision only — peripheral fields are always maintained. Although loss of ability to read and drive may be caused by macular degeneration, the disease does not lead to complete blindness.
The disease becomes increasingly common amongst people in each succeeding decade over 50. By age 75, almost 15% of people have this condition. Other risk factors are family history, cigarette smoking, and being Caucasian.
|This is an example of what a patient with advanced macular degeneration might see.
|Macular degeneration is caused by hardening of the arteries that nourish the retina. This deprives the sensitive retinal tissue of oxygen and nutrients that it needs to function and thrive. As a result central vision deteriorates. There are two main types of AMD. Dry and Wet|
|The central portion of the human retina contains a yellow pigment called the macular pigment. This pigment helps protect the sensitive receptors in the retina, particularly from the potentially harmful effects of blue light. Macular pigment can only be made in the eye from the food we eat. The density of the pigment has been shown to be linked to the type of diet and is reduced in those who smoke.|
There are two main types of AMD: the “dry” form and the “wet” form, based on the absence or the presence of abnormal growth of blood vessels under the retina. Most people with AMD have the dry form.
Currently there is no proven treatment for the dry type, but the loss of vision tends to be milder and the disease progression is rather slow. Recent research has shown that it’s progress may be slowed by altering lifestyle, for example by stopping smoking and increasing macular pigment levels.
Approximately 15% of patients with AMD have the wet form, where there is a growth of abnormal blood vessels under the retina, which can cause leakage, bleeding, and scarring, resulting in more rapid and severe vision loss. About 80% of severe vision loss is due to the wet form as compared to 20% due to the dry form.
The wet form can manifest in two types: classic or occult. Over 70% of patients with the wet form have the occult type. So far, only the classic wet type is treated with conventional laser photocoagulation to stabilize vision or to limit the growth of abnormal blood vessels. The remaining majority of patients with wet AMD cannot be treated with the laser procedure. Also, the current laser treatment does not improve vision in most treated eyes because the laser destroys not only the abnormal blood vessel but also the overlying macula. Better treatment options are obviously needed.
What happens to Vision
Some people with macular degeneration notice that straight lines in a landscape – such as telegraph poles, the sides of buildings or streets, appear wavy. Other symptoms include blurring of type or a page of print, with dark or empty spaces that may block the centre of the field of vision.
Fortunately, macular degeneration rarely results in complete blindness since side vision is usually unaffected. Although activities that require sharp vision such as reading, sewing or driving can be difficult, most people maintain their independence and should be able to get around outside and perform most household duties.
There is (currently) no known cure, but there are many indications that a good diet and healthy life style (particularly not smoking) will considerably reduce the chance of suffering from ARMD.
It is possible to carry out a simple test, to see if you might be suffering already without even knowing about it. In the early stages vision loss is only small and the brain cleverly covers up the defects so you don’t notice. The AMSLER grid is a simple visual test that you can carry out on yourself in a few minutes
Some bluring of picture and difficulty in
viewing central areas
More severe bluring and large
central part of picture missing
THE AMSLER GRID
An Amsler grid is a useful tool for monitoring your central visual field. It is an important way to detect early and sometimes subtle visual changes in a variety of macular diseases such as ARMD (age-related macular degeneration) and diabetic macular oedema. It is also helpful in monitoring changes in vision once they have been detected. With the Amsler grid, each eye is tested separately by you. This helps you to recognize visual symptoms which are in one eye only
- Test your vision with adequate lighting.
- Wear your reading glasses or look through the reading portion of your bifocals (if you normally read with spectacles).
- Hold the Amsler grid at normal reading distance (about 35cm).
- Cover one eye at a time with the palm of your hand.
- Stare at the center dot of the chart at all times.
- Do not let your eye drift from the center dot.
|Ask yourself the following questions as you check each eye separately:||
If the answer to any of these questions is “yes” (and this has not been noticed by you before), you should contact your optometrist or doctor as soon as possible for an examination.
Sometimes these changes may mean that there is leakage or bleeding in the back of the eye causing swelling of the retina.
These images are copied from the Wikipedia website
What can you do to reduce the risks
Diet (needed to build Macular Pigment)
Consuming fish (like tuna) more than once per week may be beneficial
Reduce alcohol consumption (alcohol may deplete antioxidants and carotenoids in the body)
Are you overweight? Check out your own Body Mass Index (BMI)
Gentle exercise is good for you – but don’t overdo it
A Simple ARMD risk calculator
If your macular pigment levels are also low you should consider altering your diet and/or taking supplements containing lutein and zeaxanthin. If you do not know your macular pigment levels ask your optometrist to measure it for you..
|EMail – ARMD.org.uk|
|General Enquiries and further information
Please note that the main objective of this site is to provide help and infomation of a general nature about macular disease. The site has many enquiries and we do our best to provide additional information when requested. However, we are sorry to say we cannot comment on individual cases. We suggest you consult a professional clinically qualified person for specific advice.
The University of Manchester is a registered charity and donations to support research into ARMD by Dr Ian Murray’s group may be sent to him in the Visual Sciences Lab, Faculty of Life Sciences, Moffatt Building, Manchester University, Manchester M60 1QD. Cheques should be made payable to Manchester University, together with a covering note as to the source of the donation.