The macula is a tiny area of the retina at the back of the eye. It is only around 4mm long but it is responsible for all of our central vision, most of our color vision and the fine detail of what we see. This is because the macula has a very high concentration of photoreceptor cells, also called ‘rods and cones’ which detect light and send images to the brain.
Age-related macular degeneration is a painless condition in which the macular becomes damaged. There are two main forms, known as ‘dry’ and ‘wet’.
Wet macular degeneration is so called because tiny abnormal blood vessels grow behind the retina toward the macula. These leak blood or fluid, scarring the macula and leads to rapid loss of central vision. This condition can develop very quickly, so fast referral for treatment and urgent treatment is essential.
Dry macular degeneration is a gradual deterioration of the macula, usually over many years. In dry AMD the cells of the macula die off and are not regenerated. The term ‘dry’ does not mean the person has dry eyes, just that the condition is not ‘wet’ AMD.
Unfortunately, 10 to 15% of people with dry AMD also develop wet AMD. This is because new blood vessels grow to try to repair the damage to the macula. If you have dry AMD but notice a rapid change in vision it is vital to get an urgent assessment from your optometrist.
If macular degeneration occurs in one eye there is the possibility of it affecting the other eye within a few years. The speed of progression varies from person to person.
While AMD causes central vision loss and can have a devastating impact, it does not lead to complete blindness. You will still have your remaining peripheral vision.
Macular degeneration affects people in different ways. You may not notice any change in your vision in the early stages, especially if only one eye is affected. However, as macular cells deteriorate, you ability to see clearly will change.
- Straight lines such as door frames and lampposts may seem distorted and appear bent;
- Vision may become blurry or develop gaps;
- Objects in front of you might change shape, size, color or seem to move or disappear;
- Dark spots could appear in the center of your field of vision, like a smudge on glasses;
- Colors can appear to fade;
- You may have difficulties with glare and seeing in bright sunlight;
- You may experience problems adapting from dark to light environments;
- When reading at your normal reading distance words might disappear.
The causes of macular degeneration are not fully understood. However, scientists believe a number of factors could be involved in its development and progression. Knowing about these can help reduce the risk of developing the condition and protect your remaining sight. Unfortunately, because the exact cause of age-related macular degeneration is not known you may develop the condition even if you reduce your risk factors.
Age is the main risk factor for developing macular degeneration. As we get older cell regeneration decreases, so increasing the risk of developing the condition.
A diet lacking in fruit and vegetables may increase the risk of developing age-related macular degeneration. Antioxidants in fruit and vegetables help protect the body against the action of ‘free radicals’. These are unstable molecules which can damage cells or prevent cell repair.
A diet high in hydrogenated or saturated fats increases the risk of developing AMD. People who are clinically obese may also be at a higher risk. Excessive alcohol may also deplete antioxidant levels.
Studies indicate that some people with a family history of macular degeneration may have an increased chance of developing the condition.
More women than men are diagnosed with AMD.
Smoking reduces the protective effects of antioxidants on the eye and damages the eye’s structure. Smokers are three times more likely to develop macular degeneration than non-smokers Ex-smokers have only a slightly increased risk of developing the condition than people who have never smoked.
Macular cells are sensitive to the UV radiation and visible blue light which occurs naturally in sunlight. Cell damage from blue light may lead to deterioration of the macula. People with light colored eyes may be more prone to damage from sunlight.
While you cannot change your age or ancestry, lifestyle changes may help reduce the risk of AMD.
- Detect early signs with regular eye tests.
- Don’t smoke.
- Keep your blood pressure down. People with hypertension are 1.5 times more at risk than people with normal blood pressure.
- Wear lenses and filters which block UV and blue light and reduce glare, especially when in bright sunlight.
- Wear a hat with a brim or visor to shade eyes from direct sunlight.
- Limit alcohol intake to the recommended amount.
- Eat a diet low in saturated fats and rich in Omega 3 fatty acids (e.g. Oily fish, walnuts).
- Eat lots of fruit and green vegetables.
Research suggests that nutrition may play an important role in macular degeneration. The retina is thought to be protected from sun damage by a yellow substance called macular pigment. Some scientists feel that people with low levels of macular pigment may be at greater risk of developing AMD. The pigment is actually made up of types of antioxidants called carotenoids. The two thought to be especially important are lutein and zeaxanthin. They can only be obtained by eating food which contains them.
Lutein and zeaxanthin are found in almost all vegetables but especially in dark green leafy ones such as spinach and kale. A diet including at least 2 to 4 servings a week of vegetables high in lutein and zeaxanthin and/or taking eye health supplements may help reduce the risk of AMD. This may even help slow down the onset or progress of AMD.
Kale 21.9 Broccoli (raw) 1.9
Spinach (raw) 12.6 Leaf lettuce 1.8
Parsley (fresh) 10.2 Peas 1.7
Celery 3.6 Brussels sprouts 1.3
Onions (raw) 2.1 Sweetcorn 0.78
Eye charts to assess your vision;
Eye drops to dilate (widen) the pupils so that the back of the eye can be seen clearly. The drops may cause your vision to be temporarily blurred and sensitive to light, so consider taking someone with you;
A fluorescein angiogram may be used to help diagnosis. It is a photographic test to show the network of capillaries at the back of the eye to pinpoint the source of the trouble. To do this some dye is injected into a vein in the arm. The dye will temporarily change the color of urine, so be prepared.
Wet and dry AMD are treated differently.
There is currently no treatment for dry AMD. A patient should receive an opthalmic assessment within three months. Advice on living with the condition is essential, including what to do if your AMD reaches a stage where you struggle with daily tasks.
If wet AMD is caught early it can be treated with injections of a drug into the eye. This drug inhibits the growth of new blood vessels and can stabilize vision. A patient with suspected wet AMD should be seen at a retinal clinic within a week if possible. More than three weeks is too long. Rapid diagnosis is critical.
Around 10% of wet AMD patients do not respond to drug treatment and may be offered Photodynamic Therapy (PDT) instead. An injection is given into a vein over a 20 minute period. A cold laser beam is then directed onto the problem area of the macula to seal leaking vessels. Research continues into new drugs and therapies including stem cell transplant techniques.
Anyone with more advanced wet, dry or both forms of AMD could benefit from the following :
- Referral to a low vision clinic for equipment and advice to help cope with loss of central vision;
- Referral to an adult social care sensory impairment team for practical advice and assistance with daily living skills;
- Guidance on nutrition and lifestyle adaptations;
- Contact with support organizations such as the Macular Disease Society and societies for the visually impaired;
- Signposting to ‘Access to Work‘ and employment schemes for those still working.
Macular degeneration is a very frustrating condition which can greatly affect your day-to-day life. However, there are support and information to help you stay independent. It may be worth requesting training on getting around safely. There are also adaptations, equipment and resources available as well as practical techniques to help you make the most of your sight. Everyone’s vision is different so ‘try before you buy’ or ask an expert for advice
- Improve the general lighting in your home and workplace. Increase lighting levels and control glare with the use of low energy bulbs.
- Use adjustable, cool-to-the-touch task lighting for near tasks. Daylight bulbs can be helpful.
- Bright and contrasting colors can help differentiate between objects (e.g. Cups and crockery).
- A wide range of low vision equipment is available, such as magnifiers, to buy or borrow through local low vision services.
- Spectacles with filters which block UV and blue light help protect the eye and reduce glare.
- Computers with scanners and audio conversion can help to read books and access the internet.
- Large print books to buy or borrow.
- Audio books, newspapers and magazines.
- Liquid level indicators and talking equipment such as watches, wall clocks, microwaves and kitchen scales can help with everyday tasks.
- Tactile bumps can highlight switches and setting on appliances.
- Large face clocks and watches, large print stickers for keyboards, telephones with large numbers and brightly colored kitchen implements can also be helpful.
People with central vision loss can still see with their peripheral or side vision. You can learn skills that may help you make the best use of your remaining vision and help you to stay independent.
Eccentric Viewing is a technique that enables you to use your peripheral vision more effectively.
An Amsler grid can help you to monitor your own vision at home.
1) Hold the grid about 30cm apart, your normal reading distance. Wear your usual reading glasses if needed, but not Varifocals.
2) Cover your left eye and look at the central dot.
3) Are all the lines straight and even, or any wavy, distorted, blurred or have gaps?
4) Are any pieces of the grid missing?
5) Next, cover your right eye and repeat.
6 Are all the lines straight and even, or are any wavy, distorted, blurred or have gaps? If you see any sudden change in your vision in either eye, contact your ophthalmologist immediately.
Perform this check as often as your ophthalmologist recommends.
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