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特集：医療英語 > 第 9 回：A Brief Look at Age-related Macular Degeneration (加齢(性)黄斑変性症)
Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries, and the third leading cause of visual impairment globally1. It affects people over the age of 50 and can lead to a significant decrease in quality of life and independence. Tasks such as driving, walking and reading can be greatly affected.
AMD affects the central field of vision and occurs when the central (or macular) retina develops degenerative lesions. There are two forms of AMD: "dry" and "wet".
Wet AMD is characterized by choroidal neovascularization, or growth of abnormal blood vessels from the choroid underneath the macula. These abnormal blood vessels grow toward the macula and leak blood and fluid into the retina, resulting in distortion (straight lines look wavy), blind spots and loss of central vision. Eventually these abnormal blood vessels scar, which leads to permanent central vision loss.
Dry AMD is more prevalent than wet AMD and vision loss is more gradual. Most patients with dry AMD will not lose central vision, however the dry form can lead to the wet form. People suffering from the wet form, about 10% of all people with AMD, are usually those who experience the most serious loss of vision2.
The main risk factor for AMD is ageing. Researchers believe that other risk factors may include tobacco use, genetic tendencies, degree of eye pigmentation (light colored eyes are at greater risk), arterial hypertension, ultraviolet rays and eating a non-balanced diet3.
Symptoms of AMD include distorted central vision, the appearance of dark and blurry areas or white out in the central vision, and diminished color perception. If patients experience any of these symptoms it is imperative that they see an ophthalmologist as soon as possible.
Prevention and treatment options are currently limited. Lasers, dynamic phototherapy and anti-angiogenesis drugs may retard AMD's progress, but early detection is very important. A recent study, AREDS (Age-Related Eye Disease Study), conducted by The National Eye Institute of the National Institutes of Health in the United States demonstrated that vitamins C, E, beta carotene, zinc and copper can decrease the risk of vision loss in people with intermediate to advanced dry macular degeneration4. Special aids that produce enlarged images of nearby objects may help those with impaired vision.
Scientists are currently searching for better ways to detect, treat and prevent vision loss in people with AMD. For example, they are studying submacular surgery and retinal translocation, which are surgical procedures to remove the abnormal blood vessels and rotate the macular center away from the abnormal blood vessels, respectively. In other studies, scientists are investigating the possibility of transplanting healthy cells into a diseased retina and researching certain anti-inflammatory treatments.
- Please summarize the article. What is the main point of the article?
- Please describe AMD.
- How does AMD affect patients' quality of life?
- What are the symptoms of AMD?
- What are the risk factors?
- What options are available for treating AMD?
- What types of treatments are scientists currently researching?
- World Health Organization. Magnitude and causes of visual impairment. Fact sheet No. 282. November 2004 and one Accessed 23 June 2006.
- WebMD. Eye health: Macular degeneration. Accessed 23 June 2006.
- World Health Organization. Age related macular degeneration. Accessed 23 June 2006.
- National Eye Institute of the National Institutes of Health in the United States. The AREDS Formulation and Age-Related Macular Degeneration. Accessed 23 June 2006.