Age Related Macular Degeneration


About AMD
Symptoms of AMD
Kinds of AMD
The Importance of Frequent Vision Testing

Age-related macular degeneration (AMD) is the leading cause of severe vision loss among older adults in the Western world, affecting over 25 million people in the USA alone, primarily the elderly. The worldwide incidence of the disease grows from 1 in 10 people over the age of 60 to more than 1 in 4 people over the age of 75. There are close to 2 million with vision loss due to advanced AMD and more than 600,000 that are legally blind due to the disease in North America. According to the AMD Alliance, macular degeneration is more common than Parkinson’s disease, Alzheimer’s disease, Breast Cancer and Prostate cancer combined.

Age-related macular degeneration is a disease that damages the macula, the central portion of the area at the back of the eye called the retina. The macula allows for central vision and also lets you see color and fine detail—all of which are important to daily activities such as reading and driving. The macular damage caused by AMD causes central vision loss. In most cases, patients will retain peripheral vision and be able to see shapes, light and movement.

Image courtesy of the NEI.

Symptoms of AMD
Symptoms of Age-related macular degeneration (AMD) can include:

•A spot or hazy section blocking the center of someone`s vision
•Distortion or waviness when looking at an image
•Distortion of lines on the Amsler Grid
Changes in vision should trigger immediate evaluation from an eye doctor. For patients over the age of 50 with a family history of AMD or smokers – routine yearly eye exams are a must. Detection of the early signs of AMD is essential to help preserve as much of their vision as possible.

The majority of people with AMD have central scotomas. Scotomas are retinal areas with reduced light sensitivity compared to sensitivity results of normal sighted subjects. Scotomas are specified by the retinal location in that central scotomas are retinal areas with reduced light sensitivity involving the fovea, while paracentral scotomas are retinal areas with reduced light sensitivity within the central 20° of the visual field but not involving the fovea.

Kinds of Age-related macular degeneration
There are 2 kinds of age-related macular degeneration (AMD): dry and wet. Dry AMD is more common, representing approximately 90% of all AMD cases, and is generally not as damaging to vision as the wet form. Dry AMD can convert into wet AMD at any time.

AMD is also classified into different categories:

Category 1:Few small (< 63 micrometers [µm]) or no drusen
Category 2:Early AMD, having many small drusen or a few intermediate-sized (≥ 63 µm and <125 µm) drusen.
Category 3:Extensive intermediate drusen or at least one large (≥125 µm) drusen.
Category 4:Advanced AMD in 1 eye, either Geographic Atrophy (GA) in the center or neovascular AMD
In dry AMD, yellowish, fatty deposits called drusen collect in the macula. Serious vision loss is rarely caused by dry AMD; however as many as 20% of Dry AMD patients will progress to wet AMD. There are no approved treatments for dry AMD, although vitamins, antioxidants and zinc supplements may slow its progression. Most dry AMD patients have no symptoms, and an eye doctor may need to conduct a variety of eye exams to aid in diagnosis.

Genetic risk for AMD may predict the therapeutic benefit of vitamins and nutritional supplements. A longitudinal Dutch study has determined that individuals with the CFH and ARMS2 risk alleles benefit from diets rich in nutrients known to slow the progression of AMD while progression in those without genetic risk factors appears to be independent of diet.

Wet AMD occurs when abnormal blood vessels grow under the retinal center. These may be very fragile and leak blood and fluid. This process can damage the macula or create a retinal scar.

Due to the rapid onset of macular damage, a noticeable blurring or even loss of central vision are frequently the first symptoms noted. The vision loss may be permanent because abnormal blood vessels and scar tissue are actually destroying normal retinal tissue. Once lost, these light-sensitive cells in the retina cannot be replaced.

If a person has wet AMD in one eye, there is a 35% chance of contralateral wet AMD within 5 years. The most important action to preserve vision is to establish a schedule of regular retinal re-evaluation by an eye care professional.

The Importance of Frequent Vision Testing
The best defenses against vision loss due to AMD are:

•Regular eye exams
•Awareness of its warning signs
•Ongoing vision monitoring through self-examination
With eye exams & awareness, it is important to self-monitor for signs of AMD. Early vision changes often affect only 1 eye and occur gradually over time. One simple home-based test uses the “Amsler grid.”

The grid is placed 12 inches away at eye level in good lighting .

•Corrective lenses are worn if required. One eye is covered and vision is directed for 1 minute at the grid’s center dot
•A positive test is characterized by the perception of deviation in the regularity of the pattern
•Each eye should be tested separately
A positive test must elicit prompt eye evaluation.

While a useful adjunct, regular use of the Amsler grid cannot detect nascent vision loss and is not a substitute for regular eye exams and appropriate retinal imaging.

However, since only an eye doctor can determine if you have dry or wet AMD, Amsler grid self-examinations do not replace regular eye exams.


About Advances In Sight

Born in Denver Colorado. Attended Wheat Ridge High School. Attended undergraduate at New Mexico University. Received his Doctor of Optometry degree at Southern California College of Optometry. Has two adult children who also live in Colorado. He enjoys golf, and skiing
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