Age-Related Macular Degeneration (AMD) - Cause of Vision Loss in Old Age
Did you know that people who are aged 50 and older can develop problems with the sharpness of their central vision? These people are said to have AMD or Age-Related Macular Degeneration. According to the Centers for Disease Control and Prevention, there are about 1.8 million Americans aged 40 and older who had AMD in 2008 and the number is expected to rise to 2.95 million by 2020. In the UK, there are about 110,000 people who became blind because of AMD in 2008.
With such alarming statistics, we need to be aware about the basic information on AMD. This hub will focus on answering questions like: What causes AMD? Who are at risk of having AMD? What are the symptoms of AMD and what are the treatments?
What is AMD?
As mentioned above, AMD means Age-Related Macular Degeneration. It is one of the common eye problems associated with aging. In this condition, there is gradual thinning of the macula, which is a very sensitive part of the retina in the eye and is responsible for the sharpness and clarity of a person's central vision. Since the macula is responsible for the central vision, people with AMD do not experience total loss of vision. They can still see objects using their side vision.
What Causes AMD?
AMD can occur as Dry AMD or Wet AMD. The causes of these two forms of AMD needs to be differentiated.
Patients with Dry AMD experience having a blurred spot in the center of their vision in one eye only or both eyes. Depending on the degree of blurred vision (from none to severe), the patient may be categorized as being in the early, intermediate or advanced stage .
The degree of dry AMD also depends on the amount of Drusen. Drusen are small or large yellow or white deposits found under the retina often found in people starting age 60. They are seen only when a person undergoes a comprehensive dilated eye exam.
In the early stage of Dry AMD, there are only a few small to medium-sized drusen which may not cause any vision loss. In intermediate AMD, there can be many medium to large-sized drusen effecting a blurred spot in the center of the vision. In advanced AMD, there are more large-sized drusen causing a bigger and darker blurred spot in the center of the vision.
Dry AMD can progress to become Wet AMD. Wet AMD occurs when abnormal blood vessels found behind the retina grow under the macula. When these blood vessels leak, blood and fluid damage the macula and can cause retina scarring and quick loss of the central vision. The Amsler grid test confirms the condition of Wet AMD when wavy lines appear in the grid.
Who are at risk of having AMD?
People aged 50 and older are at risk of having AMD. Aside from the age factor, studies show that people who smoke, of Caucasian descent and people with family history of AMD are at risk of having AMD.
What are the symptoms of AMD?
In the early stages of Dry AMD, there are no apparent symptoms. The first observable symptom of Dry AMD is when blurry central vision occurs or when objects do not appear as bright or clear as they used to. Patients with Wet AMD see wavy lines instead of straight line or may have a blind spot.
If you are experiencing any of these symptoms, you should see your eye care professional or ophthalmologist and undergo several eye exams including visual acuity test, dilated eye exam, Amsler grid and flourescein angiogram (to detect leaking blood vessels in the eye).
How is AMD treated?
There is no cure for AMD, but there are two things that people can do in relation to AMD. People can either lower the risk of having AMD or people who have been diagnosed with AMD can slow down its progress. In regard to the latter, it is very important that AMD is detected early.
Improved Nutrition to Prevent AMD
As people age, visual sensitivity decreases thus there is loss of vision. According to studies, proper nutrition plays an important role in slowing down this decrease in visual sensitivity. A diet that is high in carotenoid, antioxidants and omega-3 fatty acids can help lower the risk of people having eye problems in old age including AMD. This translates to eating plenty of orange and green, leafy vegetables and fish to lower the risk of having AMD. Please refer to the table to see the list of foods that can help improve nutrition to prevent AMD.
According to an article by Dr. George Torrey, two particular carotenoid pigments can increase macular pigment density and reduce the risk of age-related macular degeneration. Lutein and zeaxanthin are the pigments found in the central region of the retina: lutein is dominant in the peripheral retina while zeaxanthin is dominant in the central macula. Studies showed that consuming 6 mg of lutein per day decreased the risk for macular degeneration by 43%.
Also, according to the Age-Related Eye Disease Study (AREDS), patients in the early or intermediate stages of AMD can take high doses of antioxidants and zinc to avoid having advanced AMD or severe loss of vision.
List of Foods that Can Help Prevent Macular Degeneration
Important Components in Food
Sample of Foods
Antioxidant - Vitamin C
green peppers, citrus fruits, tomatoes, broccoli, strawberries, yams, leafy vegetables, cantaloupe
Antioxidant - Vitamin E
eggs, fortified cereals, fruit, wheat germ, nuts/nut oil, vegetable oil, whole grains
omega-3 fatty acids
salmon, sardines, walnut, flaxseed oil
Carotenoid - lutein
kale, turnip greens, collard greens, spinach, brocolli, papaya, oranges, mango, red grapes, green bell pepper
Carotenoid - zeaxanthin
egg yolk, yellow corn, spinach, collards, orange juice, lettuce, orange bell pepper, mango, apricots, peaches
Treatments for People Diagnosed with AMD
On the other hand, people who have been diagnosed with AMD early can have several options to slow down its progress to advanced or wet AMD.
- Anti-VEGF injection. The VEGF or vascular endothelial growth factor is found in high levels in patients with wet AMD and promotes the increase of abnormal blood vessels in the macula. The anti-VEGF injection helps block the effects of VEGF. This treatment is also known as antiangiogenic treatment.
- Photodynamic therapy. This therapy uses a drug called verteporfin which is injected into a vein in the arm. When the drug reaches the blood vessels in the eye, the doctor shines a laser beam to activate the drug in the eye. The drug then destroys new blood vessels and slows down the progress of vision loss. This procedure is relatively quick and can be done in 20 minutes.
- Laser surgery. This treatment uses intense laser beam to destroy new blood vessels in the macula. This option is rarely used because it may destroy nearby healthy tissues.