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Macular Degeneration

Macular Degeneration Overview

The diagnosis of macular degeneration is becoming increasingly more common due to patient awareness, physician access, groundbreaking improvements in treatment, and the relentless graying of the population exponentially increases the percentage of the population at risk for this condition. Thus, macular degeneration is a formidable challenge to patients, their doctors, and our society as the costs for delivering state-of-the-art care increase.

Macular degeneration, also called age-related macular degeneration (AMD or ARMD) or the now discarded term senile macular degeneration (SMD), describes a variety of pathologic but extremely common conditions that affect the macula (a portion of the retina of the eye) and, therefore, central vision. Central vision is what you see directly in front of you rather than what you see at the side (or periphery) of your vision.

Macular degeneration is caused when part of the retina deteriorates. The retina is the interior layer of the eye consisting of the receptors and nerves that collect and transmit light signals from the eye into the optic nerve, then to the brain for interpretation as our sense of vision. The macula is the central portion of the retina and is responsible for detailed vision and color vision, the vision we use to read, thread a needle, sign a check, or recognize faces. The macula is a highly specialized part of the nervous system and the eye in which the photoreceptors that react to light stimulus and the neurons that interpret and transmit these signals are precisely organized and densely compacted. It is the macula that allows humans to see 20/20, or an eagle to spot a small rodent on the ground hundreds of feet below.

Age-related macular degeneration is the leading cause of legal blindness in people older than 55 years in the United States. Age-related macular degeneration affects more than 1.75 million individuals in the United States. Owing to the rapid aging of the U.S. population, this number is expected to increase to almost 3 million by 2020. Because overall life expectancy continues to increase, age-related macular degeneration has become a major public-health concern.

There are two types of age-related macular degeneration:

  • Dry (atrophic) form: This type results from the gradual breakdown of cells in the macula, resulting in a gradual blurring of central vision. Single or multiple, small, round, yellow-white spots called drusen are the key identifiers for the dry type. These spots are located in the back of the eye at the level of the outer retina and are detected by examination of the retina with specifically engineered lenses, a slit-lamp biomicroscope, or an ophthalmoscope. Spots typically become visible when a person reaches his or her late 30s or older but are much more common in people over the age of 70. People with these spots may have excellent vision and no symptoms. Most people with age-related macular degeneration begin with the dry form. The dry form of macular degeneration is fortunately much more common than the wet form. Advanced dry macular degeneration, known as geographic atrophy, is the culmination of prolonged, progressive wasting changes in the nerves and sensory retina. Geographic atrophy is the main cause of vision loss in dry AMD, not drusen.
  • Wet (exudative or neovascular) form: In the wet form of macular degeneration, newly created abnormal blood vessels grow under the center of the retina. These blood vessels leak, bleed, and scar the retina, distorting or destroying central vision. Vision distortion usually starts in one eye and may affect the other eye later. In contrast to the dry type, vision loss may be rapid in the wet type of macular degeneration.
    • Wet macular degeneration affects only about 15% of people who have age-related macular degeneration but accounts for two-thirds of the people who have significant visual loss.
    • More than 200,000 new cases of wet age-related macular degeneration occur each year in the United States.
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ARMD, Nonexudative »

Age-related macular degeneration (AMD) is the most common cause of irreversible visionloss in the developed world.

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