Macular Degeneration
Macular Degeneration
Macular degeneration is a painless eye condition that causes a gradual loss of 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. See image below.
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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 is often wet due to bleeding and swelling of blood vessels in the retina due to diabetes and other diseases and requires treatment as soon as possible. It causes straight lines to appear crooked due to the macular swelling.
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.
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. 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.
If you have macular degeneration, your central vision will still be blurred, even when you wear glasses.
Dry age-related macular degeneration:
- you need brighter light than normal when reading,
- it is difficult to read printed or written text (because it appears blurry),
- colours appear less vibrant,
- you have difficulty recognising people’s faces, or
- your vision seems hazy, or less well defined.
If you are experiencing any of these symptoms, you should make an appointment with your ophthalmologist or optometrist (a health professional who specialises in diagnosing vision problems and eye conditions).
Wet age-related macular degeneration:
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.
- Visual distortions – for example, straight lines may start to appear wavy or crooked.
- Blind spot – this usually appears in the middle of your visual field. The longer a blind spot is left, the larger it will become. This is known as a central scotoma.
You should seek immediate medical assistance from your ophthalmologist if you, or someone that you know, experience 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.
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:
Best’s disease – a hereditary (runs in families) type of progressive macular degeneration which is also sometimes known as Best’s vitelliform macular dystrophy.
Stargardt’s disease – a condition that affects the macula (middle part of the retina) and, like Best’s disease, runs in families.
Sorsby’s dystrophy – an inherited condition that often begins at around 30-40 years of age and causes some loss of vision.
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 Retinal Pigment Epithelial (RPE) layer 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 layer 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.
Risk factors:
- Age – the older you get, the more at risk you are of developing macular degeneration. The condition usually affects people who are over 50 years of age.
- Gender – macular degeneration is more common in women than it is in men.
- Genetics – it is thought a problem with a certain gene (the information you inherit from your parents) may play a role in macular degeneration. However, the specific genetic problem has not yet been identified.
- Smoking – some studies have shown that smoking can increase your risk of developing macular degeneration.
Sunlight – if you are exposed to lots of sunlight during your lifetime, your risk of developing macular degeneration may be increased. To protect yourself, you should wear sunglasses in bright sunlight. Also wear anti-glare glasses when working or reading on digital devices.
Referral
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.
Amsler grid: (As seen above)
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.
Fluorescein angiography:
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).
Optical Coherence tomography (OCT):
Optical 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 are run by optometrists and occupational therapists. They can provide helpful advice and practical support to help minimise the affect dry AMD or any low vision has on your life. For example, things that may make it easier for you to carry out close detailed work include:
- magnifying lenses,
- large print books, and
intensive (very bright) reading lights. - Special computers to enlarge the words of a book you read.
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
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.
Anti-VEGF medication
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:
ranibizumab (brand name Lucentis),
pegaptanib (brand name Macugen), and bevacizumab (brand name Avastin).
Ranibizumab:
Until recently, many people had to pay to have anti-VEGF treatment carried out on a private basis. However, some anti-VEGF treatments, are now approved and paid by some medical aids.
Other anti-VEGF treatments:
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 which your ophthalmologist will discuss 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, lutein and ziaxanthin.
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 effects of vitamins and minerals on AMD before their effectiveness can be definitively proven.
For more information please contact:
Retina South Africa
Sharecall number: 0860595959 (SA only)
Telephone: +(27) 114501181
Email: headoffice@retinasa.org.za
