What is Age-Related Macular Degeneration (AMD)?
AMD is a common eye condition and a leading cause of vision loss among people age 50 and older. It causes damage to the macula, a small spot near the center of the retina and the part of the eye needed for sharp, central vision, which lets us see objects that are straight ahead. In some people, AMD advances very slowly and vision loss is mild or does not occur for a long time. In others, the disease progresses quickly and may lead to severe vision loss in one or both eyes. As AMD progresses, people may notice a blurred area near the center of vision. Over time, this blurred area may grow larger or blank spots or distortion may develop in the central vision. AMD does not cause complete blindness. However, the loss of central vision may interfere with many daily activities, such as the ability to read, drive or see faces.
Symptoms:
Gradual loss of the ability to see objects clearly
Objects appear distorted in shape and straight lines look wavy or crooked
Loss of clear color vision
Dark or empty area appears in the center of vision
Stages of AMD:
AMD is typically characterized as either “dry” atrophic or “wet” exudative. Approximately 85-90% of cases are the dry type, while 10-15% are the wet type. AMD is further broken down into three stages.
Early AMD
Early AMD is diagnosed by the presence of medium sized drusen (yellow deposits beneath the retina). This stage typically progresses slowly and central vision is usually not affected.
Intermediate AMD
People with intermediate AMD typically have large drusen, pigment changes in the retina, or both. At this stage there may be some vision loss, but there still may not be any noticeable symptoms. These changes may only be detected during a comprehensive dilated eye exam.
Late AMD
In addition to drusen, people with late AMD have vision loss from damage to the macula. There are two types of late AMD:
Geographic atrophy: Gradual breakdown of the cells in the macular and the tissue beneath the macula. These changes cause vision loss.
Neovascular AMD:
This is also called “wet” AMD. Abnormal blood vessels grow underneath the retina. These vessels can leak fluid and blood, which may lead to swelling and damage of the macula. The damage can be rapid and severe, unlike the more gradual course of geographic atrophy. It is possible to have both types of late AMD in the same eye, and either one can present first.
Risk Factors:
Genetics – people with a family history have an increased risk
Race – Caucasians are more likely to develop AMD
Smoking – doubles the risk
Age – increased risk over 50 years of age
Eating a diet high in saturated fat
Being overweight
Heart disease or high cholesterol
Diagnosing AMD:
Comprehensive dilated eye exam to obtain a better view of the back of the eye in order to look for drusen or pigmentary changes in the macula
Amsler Grid – changes in central vision may cause the lines of the grid to look distorted, wavy, or missing
Fluorescein angiogram – a fluorescent dye is injected into the arm. Pictures are taken as the dye passes through the blood vessels in the eye. This will detect new abnormal or leaky blood vessels, a complication of “wet” AMD.
Optical Coherence Tomography (OCT) – high resolution image of the retina/macula
Treatment:
Early and Intermediate AMD
There is currently no cure for AMD. As for prevention, AMD occurs less often in those who exercise regularly, avoid smoking, and eat a healthy, balanced diet including green leafy vegetables and fish. If already diagnosed with AMD, some of these habits may help prevent further vision loss.
Researchers at the National Eye Institute conducted a study called the Age-Related Eye Disease Study. They found that daily intake of certain high-dose vitamins and minerals can slow progression of the disease in people who have intermediate AMD, and those who have late AMD in one eye.
These are the recommended supplements and dosages based on the AREDS2 Research:
Vitamin C, 500 mg
Vitamin E, 400 IU
Zinc, 80 mg
Copper, 2 mg
Lutein, 10 mg
Zeaxanthin, 2 mg
Be sure to read labels carefully. Many supplements on the market have different ingredients or dosages than what was tested in the AREDS2 study. Beta-carotene should be avoided in those who smoke.
Remember this is not a cure, and will not restore vision already lost from AMD. But it may delay the onset of late AMD, or slow its progression in those who already have it.
Neovascular AMD
Injections: An injection can be used that inhibits the growth of new abnormal blood vessels. With this treatment, sometimes multiple monthly injections are required. The frequency will depend on the individual’s response to the medication.
Photodynamic Therapy: A medication is injected into the bloodstream, which is then activated with a laser into the eye. The medication is absorbed by the new growing blood vessels, and once activated by the laser, closes off the new vessels, slows their growth, and slows the rate of vision loss. Normal blood vessels are spared.
Laser surgery: Not performed as often as the other treatment options. This involves using a laser to destroy the abnormal vessels in the eye. This treatment is more likely to be used if the abnormal vessels are away from the center of the macula and in a limited area of growth. The laser can destroy surrounding healthy tissue and cause a small “blind spot” where the retina has been scarred.
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