Age-related macular degeneration or AMD, also known as ARMD
Age-related macular degeneration (AMD) is a common eye condition among people age 50 and older. AMD gradually destroys the macula which is responsible for sharp and central vision. Macular cells slowly break down by progression of AMD, gradually blurring central vision that is needed for tasks such as reading, watching TV, writing, driving, doing close work or recognizing faces.
Macular degeneration or AMD is becoming a major public health concern because the population is aging and an increase in incidence is expected. Vision loss has restricting and profound effects on quality of life and individuals affected become increasingly dependent on care-providers for daily activities. Additionally some people who have AMD may also experience depression.
AMD is a leading cause of adult vision loss in developed countries and currently affects a quarter of over-60s in the UK and more than half of over-75s. The total number of estimated UK cases stands at around 500,000, with 26,0000 new instances of the disease confirmed every year. However, 26,000 may represent only a fraction of cases diagnosed.
Macular degeneration or AMD accounts for more than 50% of blindness in the United States. There are more than 1.8 million Americans affected with the more advanced stages of AMD, and the number of individuals affected is expected to increase by more than 50% to almost 3 million in 2020. Dry AMD is the most prevalent form (90%) among the 1.8 million patients afflicted with the disease (Huang et al., 2008, & National Eye Institute).
It is estimated that there are over 20 million cases of AMD in the U.S. and Europe. It is also estimated that up to 17 million elderly have at least early signs of AMD called Age Related Maculopathy (ARM) [http://www.nei.nih.gov/eyedata].
Although vision loss is becoming a major public health problem, current preventive and therapy options for dry AMD are limited, and therefore, preventive interventions or new treatments are needed in reducing this increasing burden on society.
Pathology of age-related macular degeneration or AMD:
Vision loss in patients with AMD is attributable to photoreceptor death in central retina. Although the exact pathogenesis of AMD is not clear, growing scientific evidence suggest a role for retinal pigment epithelial (RPE) cell damage caused by oxidative stress and possibly inflammation (Yasukawa, 2009; Hollyfield, et al., 2008), leading to photoreceptor death (Sheu et al., 2010).
The cells in the retina are sensitive to light, and particularly susceptible to oxidative damage because of its high consumption of oxygen, the transparency of the cornea, and lens that allow continuous exposure of retina to light. This creates an intrinsic vulnerability of the retina to damage via oxidative stress.
Risk factors for developing age-related macular degeneration:
Risk factors affecting development of AMD include:
– Age greater than 50- the number one risk factor in AMD
– Caucasian race
– Family history of AMD
– Smoking
Further risk factors include:
– Extended exposure to light
– Atherosclerotic vascular disease
– Nutritional deficiency (Chakravarthy et al. 2010; Sheu et al. 2010; Cangemi 2007; Thornton et al., 2005).
AMD is a disease of aging, and the only intervention available for dry AMD is nutritional supplementation.
Prevalence of AMD among adults 40 years and older in the United States
Data from http://www.nei.nih.gov/eyedata/pbd_tables.asp
About 10 million individuals in the United States are affected with AMD pathology.
About 1.7 million individuals are affected with visual impairment due to advanced AMD.
Role of nutrition and risk of developing age-related macular degeneration:
The role of nutritional supplementation in delaying the onset or progression of ocular disease, and particularly AMD is of utmost interest to healthcare professionals and patients. There is a large body of scientific evidence for eye health benefits of nutritional supplements for reducing the risk of vision loss in AMD.
A leading clinical study called the Age-Related Eye Disease Study (AREDS) found that combination of antioxidant vitamins and minerals (vitamins C and E, beta-carotene (pro-vitamin A), zinc, and copper) can slow the progression of AMD in some people. Nutritional supplementation reduced the risk of progression to advanced AMD by 25 percent, and the risk of moderate vision loss by 19 percent. In United States nutritional supplementation with the combination of antioxidative vitamins and mineral could save more than 300,000 people from vision loss over the five year period between 2006 to 2011.
Evidence from many clinical studies for eye health benefits of nutritional supplements has created a hope and constant need for development of novel remedies and therapeutics to ameliorate dry AMD and decelerate its progress by aging.
The following recommendations promote a healthy living lifestyle, and may have an impact on development and/or progression of AMD:
– Avoid smoking
– Daily exercising
– Maintaining normal blood pressure and cholesterol levels
– Protect eye from intense light, e.g., midday sun
– Adopt a healthy lifestyle and varied diet rich in fish, green and leafy vegetables
– Taking the antioxidant and multivitamin combination
It is important to note that early and intermediate stages of AMD are usually without symptoms. Therefore, a comprehensive dilated eye exam by an eye care professional is needed for diagnosis of early AMD. The eye examination may include tests for measuring visual acuity, dilated eye exam to assess the health of retina, Amsler grid test, and fluorescein angiogram to identify wet AMD. Blurred vision and difficulty recognising faces are most common symptoms of dry AMD.
We recommend regular eye exams and following a healthy lifestyle and varied diet. Engage family and friends, or seek professional counselling if you are affected by AMD or known to be at high risk of developing AMD.
References:
– Huang et al., 2008. Invest Ophthalmol Vis Sci 49(9):3864-69.
– Bartlett H, Eperjesi F. Dietary analysis and patterns of nutritional supplement use in normal and age-related macular disease affected subjects: a prospective cross-sectional study. Nutrition Journal. 2004;3:16.
– http://www.nei.nih.gov/health/maculardegen/nei_wysk_amd.PDF
– http://www.nei.nih.gov/news/pressreleases/101206.asp
