Macular degeneration is a painless eye condition that causes you gradually to lose your central vision (the ability to see what is directly in front of you). You use your central vision during activities such as reading, writing and driving.
Macular degeneration occurs when the part of your eye that is responsible for central vision (the macula) is unable to function as effectively as it used to.
Macular degeneration doesn’t affect your peripheral vision (your outer vision, sometimes known as “side vision”), so the condition won’t make you completely blind.
Types of macular degeneration
There are two types of macular degeneration, dry and wet.
Dry macular degeneration affects your eyes gradually. Although there is no treatment for dry macular degeneration, there are ways you can learn to cope with it.
Wet macular degeneration is more serious than dry macular degeneration, and can develop very quickly. It requires treatment as soon as possible.
Who is affected by macular degeneration?
Macular degeneration most commonly affects people over 50 years of age. Macular degeneration in older people is referred to as age-related macular degeneration.
Approximately 2% of people over 50 years of age have age-related macular degeneration. In people over 65 years of age, the number rises to 8%, with about 20% of those over 85 years of age having the condition. In fact, in older people, age-related macular degeneration is the most common cause of visual impairment.
Macular degeneration is more common in women than in men, although the reasons for this are not fully understood.
In rare cases, young people can also be affected. This is usually caused by a genetic condition.
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Macular degeneration is not a painful condition. In fact, some people do not even realise that they have the condition until their symptoms become more severe.
The main symptom of macular degeneration is blurring of your central vision. Your peripheral vision (outer vision) is not affected.
If you have macular degeneration, your central vision will still be blurred, even when you wear glasses.
Dry age-related macular degeneration
If you have dry age-related macular degeneration (AMD), it may take between five and 10 years before you find that your symptoms are significantly affecting your daily life.
Sometimes, if only one of your eyes is affected by dry AMD, your healthy eye will compensate for any blurring or loss of vision, which means that it will take longer before your symptoms become more noticeable.
You may have dry AMD if you find that:
If you are experiencing any of these symptoms, you should make an appointment with your GP or optometrist (a health professional who specialises in diagnosing vision problems and eye conditions).
Wet age-related macular degeneration (AMD)
If you have wet age-related macular degeneration (AMD), you may also experience other symptoms as well as blurred central vision. In wet AMD, the symptoms appear more suddenly than they do in dry AMD.
The typical symptoms of wet AMD are described below.
You should seek immediate medical assistance if you, or someone that you know, experiences any sudden changes in their vision, such as those described above.
It may be a sign you have wet AMD, which needs to be treated as soon as possible.
If you require immediate medical attention, you will either need to book an emergency appointment with an optometrist, or visit your local hospital’s accident and emergency (A&E) department. It is very important for you to seek medical attention as soon as possible to reduce the risk of the condition causing any permanent damage to your vision
The back of your eye is made up of a layer of light sensitive tissue which is known as the retina.
The retina passes nerve impulses to your optic nerve (the nerve which connects your eye to your brain). The optic nerve sends impulses to your brain so that they can be converted into an image.
The macula is at the centre of your retina, and it is the part of your eye where incoming rays of light are focused.
Therefore, the macula is a very important part of your retina, because it plays an essential role in helping you to see the things that are directly in front of you. The macula is used for close, detailed activities, such as reading and writing.
The retinal pigment epithelium (RPE) is a layer of tissue that surrounds the outer surface of your retina. The RPE passes nutrients to your retina, and helps remove waste products from your eye.
Macular degeneration in younger people
In very rare cases, macular degeneration affects younger people. It is possible to have macular degeneration from birth. In younger people, the condition is almost always caused by an inherited genetic disorder. There are a number of different inherited disorders which can cause macular degeneration, including:
Inherited conditions such as these are very rare, and age-related macular degeneration is a far more common form of the condition.
Dry age-related macular degeneration
As you get older, the RPE that covers your retina starts to get thinner as it begins to break down. This means that your retina can no longer exchange nutrients and waste products as efficiently as it used to.
Waste products start to build up in your retina and form small deposits, which are known as drusens. A build up of drusens, plus a lack of nutrients, cause the light cells in your macula to become damaged and stop working.
If the light cells in your macula are damaged, your central vision becomes blurry and less well defined.
Wet age-related macular degeneration (AMD)
Wet AMD often starts in the same way as dry AMD, as the RPE begins to break down. However, with wet AMD, tiny new blood vessels begin to grow underneath the macula.
It is thought that these vessels may grow in order to help the retina to get rid of the waste products that build up when the RPE deteriorates. However, the exact cause for the growth of these abnormal blood vessels is not known.
The new blood vessels can leak blood, or fluid, into your eye, causing the more serious symptoms that are often associated with wet AMD, such as visual distortion and blind spots.
A number of risk factors may increase your risk of developing macular degeneration. Some of these factors are listed below.
If you are experiencing the symptoms of macular degeneration, you should either visit your GP, or make an appointment with an optometrist at your local opticians.
If your optometrist or GP suspects that you have macular degeneration, you will be referred to an ophthalmologist (a doctor who specialises in diagnosing and treating eye conditions). The ophthalmologist will be able to carry out a series of tests in order to help confirm a diagnosis of macular degeneration.
The ophthalmologist will first carry out a routine check of your eyes. They will look at the back of your eyes, where your retina and macula are located, using a magnifying device which has a light attached to it. This will allow your ophthalmologist to look for any initial abnormalities around your retina.
One of the first tests that your ophthalmologist will probably carry out when trying to confirm a diagnosis of macular degeneration involves asking you to look at a special grid, known as an Amsler grid. The grid is made up of vertical and horizontal lines.
If you have macular degeneration, it is likely that some of the lines will appear faded, broken or distorted. By telling your ophthalmologist which lines are distorted, or broken, it will give them a better idea of the extent of damage to your macula.
As the macula deals with your central field of vision, the lines nearest to the centre of the grid are most likely to appear distorted. You can see an example of an Amsler grid by visiting the Macular Disease Society website (see useful links).
If your ophthalmologist suspects that you have wet age-related macular degeneration (AMD), they may carry out a fluorescein angiography. This is a special type of test which can help to confirm the type of AMD that you have.
During a fluorescein angiography, the ophthalmologist will inject a special dye into a vein in your arm. They will use a magnifying device to look into your eyes, and take a series of pictures of your eye using a special camera.
These images will allow your ophthalmologist to see if any of the dye is leaking from the blood vessels behind your macula (which is the cause of wet AMD).
Coherence tomography uses special rays of light to scan your retina and produce an image of it. This can provide your ophthalmologist with detailed information about your macula. For example, it will tell them whether your macula is thickened, or abnormal in any way, which may be an indication of macular degeneration.
Dry age-related macular degeneration There is currently no cure for dry age-related macular degeneration (AMD). With dry AMD, the deterioration of vision is very slow. You will not go completely blind as a result of dry AMD, and your peripheral vision (outer vision) should not be affected.
There is help available to help make tasks such as reading and writing easier. Getting practical help may help improve your quality of life, and make it easier for you to carry out your daily activities.
You may be referred to a low vision clinic. These clinics can provide helpful advice and practical support to help minimise the affect dry AMD has on your life. For example, things that may make it easier for you to carry out close detailed work include:
Wet age-related macular degeneration
There are a number of treatments that can help to stop the progression of wet AMD. It is very important that wet AMD is treated as soon as possible, in order for the treatment to be effective. Once sight has been lost, it cannot usually be restored. Some of the treatments available for this type of AMD are outlined below.
Photodynamic therapy is a treatment which was developed in the 1990s. It involves having a light-sensitive medicine called verteporfin injected into a vein in your arm. The medicine is able to identify the abnormal blood vessels in your macula (the part of your eye responsible for central vision), and attaches itself to the proteins in the vessels.
The next stage is to have a laser shone through your eye – this usually takes around one minute. This activates the verteporfin, which works by destroying the abnormal vessels in your macula, without harming any of the other delicate tissue in your eye. This stops the vessels from leaking blood or fluid, therefore stopping the damage the vessels are causing to the macula.
Photodynamic therapy is not suitable for everyone. It will depend on where the blood vessels in your eyes are growing, and how severely they have affected your macula. You may need to have this treatment every few months to ensure the growing blood vessels are kept under control.
Anti-VEGF medication is a newer type of treatment which can also help to stop the progression of wet AMD.
VEGF stands for ‘vascular endothelial growth factor’. It is one of the chemicals responsible for the new blood vessels which form in the eye as a result of wet AMD. Anti-VEGF medicines work by blocking this chemical, stopping it from producing the blood vessels.
The anti-VEGF medication has to be injected into your eye using a very fine needle. You will be given a local anaesthetic so the procedure should not be painful. The procedure may have to be carried out every few weeks in order for the treatment to be effective.
There are currently three anti-VEGF medications used in this type of treatment:
Until recently, many people had to pay to have anti-VEGF treatment carried out on a private basis. However, the anti-VEGF treatments, ranibizumab has been approved by the National Institute for Health and Clinical Excellence (NICE) for use on the NHS.
In order to qualify for ranibizumab on the NHS, you must meet several criteria related to your current visual acuity (ability to see), and how severely the condition is affecting you. You can view the necessary criteria for NHS ranibizumab treatment by visiting the NICE website. See the ‘selected links section for more information about this.
The NHS will cover the cost of the first 14 injections in each eye being treated. If your specialist finds that you need more treatments after the 14 injections, the manufacturer of ranibizumab has agreed to cover the cost of the treatment. However, if your condition worsens, or does not show any signs of improvement, after having treatment with ranibizumab, your treatment will be stopped.
Other anti-VEGF treatments:
The availability of other anti-VEGF medication currently depends on your local Primary Care Trust (PCT), who will usually assess each case on an individual basis.
Recent guidance issued by NICE has stated that the anti-VEGF treatment, pegaptanib, is not recommended for use by the NHS for people with wet AMD. If you are already receiving pegaptanib treatment on the NHS, your treatment will only be stopped when your specialist feels that it is appropriate to do so.
If you cannot get anti-VEGF treatment on the NHS, it is widely available on a private basis. However, this means that you will have to pay for the treatment, which can be expensive.
Anti-VEGF medication is primarily used to stop wet AMD from getting worse. However, in some cases, anti-VEGF medicines have also been shown to restore some of the sight which may have been lost as a result of macular degeneration. It is important to be aware that your sight will not be restored completely, and not everyone will experience an improvement.
Anti-VEGF treatment does not normally cause any side effects. However, you may experience the following symptoms following your injections:
In a very small number of cases, this procedure can also result in more serious complications, such as:
Your ophthalmologist will discuss the risks with you before this type of treatment is carried out.
Vitamins and minerals
Some research has found that high doses of certain vitamins may help to slow down the progression of AMD. The research found that vitamins A, C, E and beta-carotene helped, as did the minerals zinc and copper.
The research suggests that you should try taking these supplements if you are at a high risk of developing advanced AMD, where your eyesight is severely affected.
Although these vitamin and mineral supplements can be purchased from pharmacies and other retailers, you should only take those which are recommended to you by your GP or ophthalmologist. High doses of these vitamins and minerals can result in side effects, and if not taken at the correct dosage, may do more harm than good.
There also needs to be more scientific research carried out into the affects of vitamins and minerals on AMD before their effectiveness can be definitively proven.
Dr. van Wyk’s talk on Carte Blanche about Age related macular degeneration:
Beeld artikel: ‘Sien jy skielik swakker?’ 2010-08-23