Age-related macular degeneration (AMD)
Age-related macular degeneration (AMD) is an eye disease that affects approximately 600,000 individuals in the UK. As a result, AMD is the leading cause of vision loss in people aged 50 years and older. Age-related macular degeneration affects the central part of the retina called the macula. The retina is the light-sensitive nerve tissue that lines the inside of the back of the eye. It captures light and sends signals to the brain which creates an image of the world. The macula is at the centre of the retina and is responsible for seeing fine detail clearly, for example, when reading, alongside colour perception.
There are two broad subtypes of AMD. The first, dry AMD, is diagnosed in approximately 85% of patients, while the second type 鈥� wet AMD 鈥� accounts for 10 鈥� 15% of patients.
Symptoms of age-related macular degeneration (AMD)
As the macula ages, many people develop a form of AMD called 鈥榚arly鈥� AMD. This generally doesn鈥檛 cause any symptoms and does not always lead to advanced AMD (Wet AMD or Geographic Atrophy).
If it does progress to advanced AMD, you may notice symptoms such as:
- problems or changes in your central vision, with your peripheral vision remaining normal
- losing the ability to see fine details, both close-up and at a distance (for example, you may see the outline of a clock but not be able to tell what time it is)
- blurred or distorted vision
- a blind spot in your central visual field
- not being able to see as well in low light
- straight lines appearing wavy or crooked
If these symptoms are not investigated, formally diagnosed or left untreated, the central vision could get worse. This can have a significant effect on your daily life and may prevent you from working and driving, or to recognise faces.
What causes age-related macular degeneration?
AMD is caused by the gradual deterioration of the macula, primarily due to ageing and genetic factors, with a past history of smoking and nutrition throughout life being other important contributory factors.
No single exact cause of AMD exists, and its development and progression aren鈥檛 fully understood, but multiple processes are thought to contribute to its development, including oxidative stress and chronic inflammation.
In some people, the macula will show mild signs of ageing as early as 55 years old. This is known as early AMD, which slowly progresses to more advanced forms of AMD. Dry AMD is diagnosed when multiple spots of waste material, called drusen, are detected at the macula.
Wet AMD occurs usually as a late consequence of dry AMD, when abnormal blood vessels grow, these leak fluid and blood (hence the word 鈥榳et鈥�). If this condition is left untreated, it can progress quickly and cause severe damage to the macula, potentially leading to a permanent loss of central vision. However, the risk of losing all vision with AMD is usually low, as the peripheral vision remains intact.
A late and advanced form of dry AMD also exists, called geographic atrophy, where the macula tissue wastes away; the consequences on vision can be severe, but the condition generally progresses slowly.
Age-related macular degeneration diagnosis
An eye doctor will check for AMD using a comprehensive eye exam which includes:
- visual acuity tests 鈥� an eye specialist measures vision ability at various distances
- pupil dilation 鈥� eye drops are used to widen the pupil and allow a close-up microscopic examination of the retina
- OCT scanning (optical coherence tomography) 鈥� a quick but very detailed scan of the retinal structure, this is the main test for diagnosing this condition
- autofluorescence Imaging 鈥� another imaging test, involving a bright flash of light giving information about the health of the pigment layer beneath the retina
- ocular angiography 鈥� a special dye is injected into the veins and passes through the blood vessels in the retina. Pictures are then taken to allow the doctor to assess whether the blood vessels are leaking. Different dyes (fluorescein and indocyanine green) are used according to the findings. Another form of angiography can be undertaken on the OCT scanner, often all three tests are undertaken to fully understand the disease activity, and help in optimising treatment.
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Age-related macular degeneration treatments
Treatment for age-related macular degeneration will depend on the type you have.
There is currently no treatment for early AMD 鈥� your doctor will simply continue to assess the progression of the degeneration using serial OCT scanning. An Amsler grid is sometimes issued to help with self-monitoring at home.
To help prevent the development of early AMD, you should:
- refrain from smoking
- eat a balanced, nutrient-rich diet, high in dark leafy greens, yellow fruits, vegetables and oily fish
- ensure your blood pressure and cholesterol control are reviewed (and treated as necessary)
- lead a healthy lifestyle with plenty of exercise
- maintain your weight
- supplement with an AREDS2 on the advice of your specialist, only if a certain stage of macular degeneration is reached (the risk and benefits will be discussed on an individual, case-by-case basis. The AREDS2 formulation contains high doses of vitamin C, vitamin E, zinc, copper, lutein and zeaxanthin
With wet AMD, you should begin treatment as a matter of urgency, as any delay can lead to an irreversible loss of your vision.
Vision loss, however, can be prevented with regular injections of anti-vascular endothelial growth factor (VEGF) into the eye. VEGF is a chemical signal produced by diseased cells in your eye that promotes blood vessel growth (鈥榳et鈥� AMD). As a result, anti-VEGF treatment stops further growth of the blood vessels and minimises leakage from these abnormal vessels.
For this treatment to be effective, it needs to be regularly administered (on an individualised treatment regime), with regular monitoring of the treatment response by OCT scanning. You should also continuously monitor any changes in your vision and let your eye specialist know of any concerns as soon as possible, especially if the second eye is involved.
We can treat wet AMD very effectively now, providing that we catch it at an early stage. A number of different drugs are available 鈥� your specialist will discuss the best options according to your individual circumstances. Multiple new drugs are being tested, with some promising agents on the horizon, our specialists are 鈥榚arly adopters鈥� of the best medicines available.
There is no current treatment for dry AMD, though researchers are working hard at developing new treatment options. The AREDS vitamins have been shown to slow progression and cut down the risk of conversion into wet AMD, but only by a modest degree.
A number of investigational drugs are being tested for the more advanced form of dry ARMD (geographic atrophy), but none have been approved for use in the UK or Europe. We expect new treatments to become available within the next two to three years.
Visual aids may be recommended to support you as your vision changes. You may also be able to reduce the progression of vision loss by implementing the lifestyle changes recommended for early AMD. This service is offered at AOA体育平台 Eye Centre by specialist optometrists.
Otherwise, your eye specialist will continually monitor the progression of the disease.