What is Macular Degeneration?
Macular degeneration is caused when part of the retina deteriorates. The retina is the interior layer of the eye. The macula is the central portion of the retina and is responsible for detailed vision and central vision.Macular Central vision is what you see directly in front of you rather than what you see at the side (or periphery) of your vision.
Age-related macular degeneration is the most common type of macular degeneration and is the leading cause of legal blindness in people older than 55 years in the United States. Age-related macular degeneration affects more than 11 million individuals in the United States. Owing to the rapid aging of the U.S. population, this number is expected to increase to almost 20 million by 2020. Because overall life expectancy continues to increase, age-related macular degeneration has become a major public health problem.
There are two types of age-related macular degeneration:
Dry (atrophic) form:85- 90% of individuals with AMD suffer from this form of the disease, which results in degeneration of retinal layers and leads to gradual loss of central vision. This type results from the gradual breakdown of light-sensitive cells in the macula that convey visual information to the brain,and of the supporting tissue beneath the macula,resulting in a gradual blurring of central vision. Multiple, small, round, yellow-white spots called drusen are the key identifiers for the dry type. The 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 an ophthalmoscope. Spots typically become visible when a person reaches his or her late 30s or older. 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 much more common than the wet form. Geographic atrophy is one type of dry AMD that can cause severe visual loss.
Wet (exudative or neovascular) form:Wet – In the wet form, newly created abnormal blood vessels grow under the center of the retina. These blood vessels leak fluid or blood, and scar the retina, distorting vision 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, but accounts for two-thirds of the people who have significant visual loss.
More than 250,000 new cases of wet age-related macular degeneration occur each year in the United States.
Source: National Alliance for Eye and Vision Research