Macular Degeneration is caused by the deterioration of the central portion of the retina, the inside back layer of the eye that records the images we see and sends them via the optic nerve from the eye to the brain. The retina’s central portion, known as the macula, is responsible for focusing central vision in the eye, and it controls our ability to read, drive a car, recognize faces or colors, and see objects in fine detail.
One can compare the human eye to a camera. The macula is the central and most sensitive area of the so-called film. When it is working properly, the macula collects highly detailed images at the center of the field of vision and sends them up the optic nerve to the brain, which interprets them as sight. When the cells of the macula deteriorate, images are not received correctly. In early stages, macular degeneration does not affect vision. Later, if the disease progresses, people experience wavy or blurred vision, and, if the condition continues to worsen, central vision may be completely lost. People with very advanced macular degeneration are considered legally blind. Even so, because the rest of the retina is still working, they retain their peripheral vision, which is not as clear as central vision.
Types of Macular Degeneration
There are two basic types of Macular Degeneration: “dry” and “wet.” Approximately 85% to 90% of the cases of Macular Degeneration are the “dry” (atrophic) type, while 10-15% are the “wet” (exudative) type.
Stargardt disease is a form of macular degeneration found in young people, caused by a recessive gene.
Stages of Macular Degeneration
There are three stages of Age-related Macular Degeneration (AMD).
- Early AMD – Most people do not experience vision loss in the early stage of AMD, which is why regular eye exams are important, particularly if you have more than one risk factor (see below). Early AMD is diagnosed by the presence of medium-sized drusen (yellow deposits beneath the retina).
- Intermediate AMD – At this stage, there may be some vision loss, but there still may not be noticeable symptoms. A comprehensive eye exam with specific tests will look for larger drusen and/or pigment changes in the retina.
- Late AMD – At this stage, vision loss has become noticeable.
Causes of AMD
The specific factors that cause macular degeneration are not conclusively known, and research into this little understood disease is limited by insufficient funding. At this point, what is known about age-related Macular Degeneration is that the causes are complicated but include both heredity and environment. Scientists are working to understand what causes the cells of the macula to deteriorate, seeking a macular degeneration treatment breakthrough. They know the causes are not the same for Age-related Macular Degeneration as they are for Stargardt disease. Stargardt disease has a specific genetic cause in most cases, whereas AMD involves both genetic and environmental.
The biggest risk factor for Macular Degeneration is age. Your risk increases as you age, and the disease is most likely to occur in those 55 and older.
Other risk factors include:
- Genetics – People with a family history of AMD are at a higher risk.
- Race – Caucasians are more likely to develop the disease than African-Americans or Hispanics/Latinos.
- Smoking – Smoking doubles the risk of AMD.
There is currently no known cure for Macular Degeneration, but there are things you can do to reduce your risk and possibly slow the progression once you’ve been diagnosed. For example, one can pursue lifestyle changes like dieting, exercise, avoiding smoking, and protecting your eyes from ultraviolet light.
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