What Is Age-Related Macular Degeneration & What Causes It? | AMD & Low Vision Awareness Month

Age-related macular degeneration, or AMD, is a serious eye disease that can lead to vision loss. According to the American Academy of Ophthalmology (AAO), age-related macular degeneration is the number one cause of vision loss in people over 50.
 
There are two types of AMD: Wet and dry. Both wet and dry AMD involve damage to the part of the eye called the macula, which is the central portion of the retina.
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The macula plays a critical role in central vision. Central vision allows you to see objects in your direct line of sight. We need central vision to do everyday activities, such as drive, read, and recognize faces. The macula collects the images you see and transmits them to the optic nerve, which sends signals to the brain. The brain then interprets the images.
 
In dry age-related macular degeneration, the macula breaks down and thins. Dry age-related macular degeneration is much more common and affects about 80 percent of people who have AMD.
 
A second and less common type of age-related macular degeneration, referred to as wet AMD, can also develop. The cause of wet AMD is the growth of abnormal vessels beneath the retina. The blood vessels actually do more harm than good, leaking fluid or blood, which scars the macula.
 
If the macular deteriorates or is damaged, it affects its ability to receive images correctly. At first, symptoms may not be present. As the condition progresses, however, vision is affected. For example, in wet AMD, the scaring of the macular leads to blind spots and distorted vision. Vision may also become blurry, wavy, and eventually, central vision can be lost completely.
 
As the part of the retina responsible for side vision is not affected by AMD, people with AMD may maintain their side vision. However, side vision may not be as clear with AMD as without. Individuals who have advanced macular degeneration are considered legally blind.
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Stages of Age-Related Macular Degeneration

There are three stages of AMD: Early AMD, intermediate AMD, and late AMD. Each of these has their own sets of characteristics and symptoms.
 
In early AMD, most people do not have any vision loss. As a result, many people with this stage of the disease may not even be aware they have AMD. Early symptoms do not usually develop, but an ophthalmologist can diagnose the condition through an eye exam, which is why regular comprehensive eye exams are so important.
 
People who have intermediate AMD may have some vision loss, but it may be subtle. Specific eye tests that identify pigment changes in the retina can help diagnose the disease.  
 
By the time late AMD develops, people with the condition have noticeable vision loss. Some people do not seek a diagnosis until they reach this stage.
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What Causes Age-Related Macular Degeneration?

​In dry AMD, which is most common, the tissue of the macula may become thin and deteriorate. Although the breakdown of the macular occurs slowly over time, eventually it affects vision. 
 
The exact reason some people develop age-related macular degeneration is not known. According to the American Macular Degeneration Foundation (AMDF), AMD does appear to develop due to a combination of genetic and environmental factors, such as lifestyle choices.
 
What researchers have been able to identify are certain factors that increase your chances of developing AMD. Risk factors include:

• Age: Age is one of the biggest risk factors for AMD. Most people diagnosed are over the age of 65.
• Smoking: Cigarette smoking or routinely being exposed to secondhand smoke puts you at an increased risk for developing AMD. Plus, the longer you smoke the greater your risk becomes. The good news is cigarette smoking is a risk you can control. If you smoke, consider talking with your doctor about ways to help you quit.
• Family history: Having a family member, such as a parent or sibling, with a history of AMD increases your risk. Researchers have discovered genes linked to developing the disease.
• High blood pressure: High blood pressure is associated with several eye diseases, and macular degeneration may be one of them. Although additional research is needed to consider high blood pressure as a definitive risk for AMD, some studies show a link.
• Race: It appears AMD occurrence may be higher in people of certain races. According to the National Eye Institute, age-related macular degeneration occurs more frequently in people who are Caucasian than in people of Hispanic or African American decent.

• Ultraviolet light: Excess exposure to ultraviolet light can be harmful to the eyes. According to AMDF, exposure to ultraviolet light from the sun may increase a person’s risk of developing certain eye diseases, including AMD.

 
As with most eye diseases, including AMD, early diagnosis is helpful to possibly slow the progression. Having regular eye exams is key to identifying age-related macular degeneration before symptoms are noticable. If you have any questions about AMD, your risk, or having a complete eye exam with one of our eye doctors, please call our office at 508-746-8600 to schedule an appointment.