Age-related Macular Degeneration
Age-related macular degeneration (AMD) is the leading cause of legal blindness in people over age 55. It affects over 10 million adults in the U.S. alone.
AMD is the physical disturbance of the center of the retina called the macula. Roughly the size of the capital letter "O" in this sentence, the macula is the part of the retina that provides our most acute and detailed vision for reading, driving, and performing other activities that require fine, sharp, straight-ahead vision.
What is AMD?
Age-related macular degeneration (AMD) is a form of blindness that affects the very centre of your field of vision. As the name suggests, it is a disease of the macula, an anatomical part of the light-sensitive retina at the back of the eye responsible for central vision. AMD occurs in two forms: Wet and Dry. Wet AMD is associated with the growth of abnormal blood vessels which are fragile and often bleed. This can lead to a sudden deterioration of vision. Dry AMD occurs when the light-sensitive cells of the macula slowly break down, gradually blurring the vision in the affected eye. Usually, it takes many years to develop and generally affects both eyes. Individuals who have the Wet form or the advanced Dry form in one eye are at especially high risk of developing advanced AMD in the other eye. There is no pain, and the condition does not affect peripheral vision even in the advanced stages. However, independence is compromised, as day-to-day activities, such as reading, writing, recognising people’s faces, and driving, become increasingly difficult or impossible.
An increasing health problem
AMD is the leading cause of blindness in the Western World, with more than 15,000 cases diagnosed in the UK each year. It is the most common cause of poor sight in people over 60 and, as life expectancy extends, it is becoming increasingly prevalent. Although its exact cause is not known, it is believed to be influenced by a combination of genetic and environmental factors. Advanced AMD is associated with a permanent vision loss. Whilst there is no cure for AMD, a number of treatments are currently available for the Wet form. As yet, however, no specific treatments are available for the Dry form.
A healthy lifestyle can help
Although there is no long-term cure for AMD, it is possible to take precautions that may lower risk of onset and slow its progression 1,2. The following are suggestions to aid a healthy lifestyle.
Take recommended nutritional supplements – a tested combination of antioxidants and minerals can help protect your vision 1,2
- Eat a balanced diet, which includes sources of anti-oxidant vitamins and carotenoids, such as green leafy vegetables, fruit, and fish 3
- Stop smoking – smokers are at 2-3-fold higher risk of developing AMD as compared to non-smokers 4
- Maintain normal blood pressure 4
- Watch your weight 4
Anti-oxidants and eye health
Many studies5, 6 have shown that people who eat adequate levels of antioxidants tend to preserve their eyesight longer than those who don’t. Better understanding of the retina means that it is believed that harmful oxygen free radical molecules are important in the development of AMD and loss of vision. These molecules are produced by the interaction of light and oxygen, and cause chemical damage to the retina called “oxidative damage”.
It is widely believed that antioxidants can prevent this oxidative damage. The United States National Eye Institute tested this in a major 10-year study by the using nutritional supplements (antioxidants) provided by Bausch & Lomb. These supplements, containing high levels of beta-carotene, zinc, vitamins C and E, were shown to reduce the risk of developing advanced AMD by 25%1. A variety of nutritional supplements are now commercially available, but not all have the same formula as that which was used in the study. Prior to starting a supplement, you should check that it contains the right levels of ingredients or be guided by your doctor or eye specialist.
- Beta-carotene is an antioxdant related to vitamin A. It gives yellow and orange fruit and vegetables their colour. It canbe found in yellow, orange and green leafy vegetables and fruit such as carrots, spinach, broccoli, peppers, mango and peaches.
- Lutein occurs naturally in the human eye in both the macula and the lens and is thought to play a protective role against the development of AMD and age-related cataract formation. However, lutein must be derived from the diet as the human body cannot produce it. Lutein can be found in kale, broccoli, spinach, and egg yolk, and has only recently become commercially available. A new and important trial is currently in progress in the US to further clarify the role of lutein in AMD; however, the results will not be available for some time.
Antioxidant Vitamins and Mineral
In the 10-year trial1, the most beneficial formulation included the following vitamins and minerals in addition to beta-carotene:
- Vitamin C, a water-soluble dietary antioxidant and free radical scavenger. It is found naturally in foods such as citrus fruits and leafy green vegetables.
- Vitamin E, a fat-soluble dietary antioxidant which helps maintain cell membrane integrity and is active in the retina. It is found in plant oils such as soya, corn and olive oil, and also in nuts and cereals.
- Zinc, which acts as a co-factor in the formation of new cells and in several enzymatic pathways which limit oxidative damage. It is found in cereal, meat, and water
Check yourself for signs of AMD
AMD is usually detected during a comprehensive eye examination which involves dilating (widening) of the pupils. However, you can find out if you should be seeking medical advice with this simple test. AMD usually starts in one eye before the other, so you need to check each eye in turn.
With one eye covered look directly at the special Amsler grid above.
Do you see fuzziness or distortion or a blank patch right in the centre of your vision? If so you may have macular degeneration and you should seek further medical advice.
Either visit your GP, who will refer you if necessary to an eye specialist, or go directly to an optician, who will make further checks as part of a routine eye test.
Where can I get more information on AMD?
For additional information about AMD, you can register with your local branch of the Macular Disease Society (MDS), a UK-based self-help group for those suffering with AMD. You can contact the MDS by telephone at 0845 241 2041 or email at firstname.lastname@example.org. Alternatively, you could visit the MDS website at http://www.maculardisease.org.
The following organisations will also provide a lot of useful information and assistance:
AMD Alliance International
1 Age-Related Eye Disease Study Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta-carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Arch Ophthalmology 2001 Oct; 119(10):1417-36.
2 Pearce I; Dietary Supplements in AMD: Royal College of Ophthalmologists, Focus, Issue 30, 2004
3 The Eye Disease Case-Control Study Group. Dietary Carotenoids, Vitamins A, C and E, and advanced Age-Related Macular Degeneration. JAMA 1994 Nov; 272 (18): 1413-1420
4 Age-Related Eye Disease Study Group. Risk Factors for the incidence of advanced Age-Related Macular Degeneration in the Age-Related Eye Disease Study (AREDS): AREDS report no. 19. Ophthalmology 2005 April; 112(4): 533-539
Supported for educational purposes by Bausch & Lomb
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Photo courtesy of National Eye Institute, National Institutes of Health.