Age-Related Macular Degeneration
Age-related macular degeneration (also known as AMD, ARMD & macular degeneration) is a condition that affects a tiny part of the retina called the macula which is used to control visual acuity. This condition is not painful, does not lead to a total loss in sight, however, does cause problems with your central vision.
AMD affects the vision you use when looking directly at something, for example when you are watching television or reading a newspaper. It can cause your central vision to become distorted and blurry and in time can lead to a blank patch in the centre of your vision.
Macular degeneration is the leading cause of vision loss amongst the over 50s and is thought to affect more than 500,000 people in the UK to some degree.
There are two types of AMD – “wet” AMD and “dry” AMD. They are called “wet” and “dry” due to what can be seen when your macular is examined and not because of how your eye feels.
The “dry” form accounts for around 90% of cases and occurs when there is a build-up of waste materials beneath the macular and thinning of the retina at the macula. Most people with this condition have close to normal vision or milder sight loss.
The “wet” form, also known as neovascular or exudative AMD is more serious. The “wet” form develops when the cells of the macula stop working correctly and the body begins to grow new blood vessels to fix the problem. Unfortunately, these blood vessels grow in the wrong place and leak blood and fluid into the retina, causing distortion of vision, as well as blind spots and loss of central vision. These abnormal blood vessels and their bleeding eventually form a scar, leading to a permanent loss of central vision.
Age-related macular degeneration is painless and symptoms of AMD tend to take 5-10 years to become severe. However, severe vision loss due to wet AMD can develop more quickly.
If AMD is present in just one eye you may not become aware of it until it is in its advanced stages, as your other eye will still see the things you are looking at with your central vision. Symptoms are much more noticeable when both eyes are affected.
The main early indicator is the worsening of your central vision despite using your normal glasses. In the early stages, you may need brighter light to be able to continue to read. Written words may look blurry and colours may appear less bright.
As the condition gets worse a blind spot will develop in the centre of your visual field. This blind spot tends to become larger over time as more and more rods and cones degenerate in the macula.
An early symptom of wet AMD is visual distortion. This can lead to straight lines appearing wavy or crooked.
Those suffering from severe AMD may experience visual hallucinations (see Charles Bonnet Syndrome). These hallucinations can be anything from simple patterns to more detailed pictures such as landmarks or animals. These hallucinations are not the result of a mental illness.
Diagnosis, Screening and Tests
If you develop symptoms associated with AMD, your doctor or optician will refer you to an eye specialist. This should be done as a matter of urgency, if you have wet AMD this can worsen rapidly but is treatable.
The eye specialist may ask you to look at a special piece of paper with horizontal and vertical lines to check your visual field. If you find that any section of the lines is missing or distorted than you may have AMD. A slit-lamp microscope may be used to exam the back of your eye.
Ocular coherence tomography is a test that is becoming more commonly used. This test uses special light rays to scan the retina. It can give very detailed information about the macula and will identify any abnormalities. Ocular coherence tomography is useful in determining whether AMD is the wet or dry form, and to monitor treatment.
A number of treatments are currently available for wet AMD. These treatments generally work by stopping the growth of new blood vessels. This means the treatments generally need to be given quickly once the blood vessels start to grow in your eye. If the blood vessels are left to grow for too long they may scar the retina and cause irreversible damage.
Unfortunately, there is currently no treatment for dry AMD. This is due to the fact that dry AMD doesn’t involve new blood vessels growing.
Treatments for wet AMD
The newest treatment available on the NHS for wet AMD is an anti-vascular endothelial growth factor (anti-VEGF) drug. As new blood vessels develop in your eye, your body creates a chemical that stimulates further new blood vessel growth. Anti-VEGF drugs work against these chemicals and stop the vessels from growing. By stopping this growth further damage to your sight is prevented.
The medicine used must be injected into the vitreous (the gel-like substance inside your eye). This is known as an intravitreal injection.
Prior to the injection, you will be given anaesthetic eye drops to numb the pain, an antibiotic drop to help prevent infection and another drop to dilate your pupil.
The injection should not be painful however your eye may be a little sore after the anaesthetic wears off.
The sight in the treated eye may be blurry because of the drop used to dilate your pupil, this should, however, wear off after a day. Some patients find that they have minor swirls in their vision in the days following the injection. Your eyes may water a bit after the injection and become red or irritated however this will improve after a few days.
If your eye becomes very painful, red or you notice that your vision is actually getting worse you should contact your hospital immediately to let them know.
Generally, you will need to receive more than one injection of anti-VEGF medication. Normally a course of three monthly injections is given initially and then you need to be monitored every four to eight weeks depending on what particular drug was given to check how well the treatment is working. Your ophthalmologist will advise you on how often you need to get your eyes tested. Many people require more injections than the initial three.
Usually, anti-VEGF treatments have a very high success rate and in the majority of people, symptoms stop getting worse. Around 25-30% of people report an improvement in their vision as a result of the treatment.
Anti-VEGF treatments are normally the first treatments offered to people with wet AMD. However, sometimes it is necessary to try a different treatment known as Photodynamic therapy or PDT. This is a form of laser treatment that uses a light-sensitive drug and a low energy (cold) laser to stop new blood vessels from growing.
You will receive an injection, usually in the arm, of a light-sensitive drug known as Verteporfin (Visudyne). Once this drug has travelled to the new blood vessels which grow in wet AMD, your ophthalmologist can target an extremely bright light (a cold laser) onto these blood vessels. The laser causes the drug to react which seals off any new blood vessels that may be growing.
This treatment also has to be carried out at the early stages of the blood vessel growth to ensure that the new blood vessel growth is not causing damage.
Treating dry AMD
Although there is currently no proven treatment for dry AMD some evidence suggests that high doses of vitamin A, C and E and the minerals zinc and copper when taken together may help to slow the progression of dry AMD.
A number of over the counter vitamin products are available that have been specifically designed for people with dry AMD. There is, however, no evidence that taking these vitamins will stop you from developing AMD in the first place.
One of the best ways to prevent AMD is to stop smoking. According to recent research by experts at the University of Manchester, smokers are up to four times more likely to develop macular degeneration.
Eating plenty of dark, leafy greens such as raw spinach, kale and collard greens may decrease your risk of developing advanced or wet AMD.
Taking vitamins and minerals in pill form is also a great idea for many health reasons including general eye care. Ask your doctor to recommend what vitamins and minerals are best for you based on your specific health needs.
Eating fish regularly can help to prevent macular degeneration. Research from the University of Sydney suggested that people who ate fish at least once a week were 40% less likely to have beginning stage AMD develop than those who ate fish less than once a month or not at all.
Regular exercise and maintaining a healthy weight will help to reduce your risk of developing AMD. Ensure that you are eating a balanced diet and are consuming fruit and nuts every day. It is also a good idea to reduce refined carbs in your diet. Highly refined foods such as white bread, pretzels and baked white potatoes have a high glycaemic index and cause a rapid increase in blood sugar and insulin release. Aim to eat lower glycaemic foods such as brown rice, whole grain bread and carrot juice.
It is always a good idea to wear a hat, or sunglasses with a high level of UV protection to protect your eyes from harmful UV rays.
One of the most important preventions for AMD is to have regular eye exams. If you are aged between 45 and 60 you should receive an exam once every 2-3 years. If you are over 60 you should be receiving an annual examination. Regular eye tests can help to identify AMD and monitor it to allow for proper treatment.