Age-Related Macular Degeneration Facts

By

Laura Semko

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Health Stories - Eyes and Vision

Age-related macular degeneration (AMD) is a disease that affects an individual's central vision, which is necessary for driving, reading, recognizing faces, and performing close-up work.

AMD is the most common cause of severe vision loss among people older than age 50. Because only the center of vision is affected, people rarely go blind from this disease. However, AMD can make it difficult to read, drive, or perform other daily activities that require fine, central vision.

AMD occurs when the macula, which is located in the center of the retina and provides us with sight in the center of our field of vision, begins to degenerate. With less of the macula working, central vision begins to deteriorate. Possible risk factors for AMD include gender (women are at greater risk), age, smoking, family history, hypertension and cardiovascular disease, obesity, and high blood cholesterol levels.

There are two primary types of AMD: dry AMD and wet AMD. Dry AMD is the most common. It occurs as the light sensitive cells in the macula slowly deteriorate, generally predominating in one eye at a time.  AMD results from cumulative, life-long oxidative damage to a layer of cells behind the retina. These retinal pigment epithelial (RPE) cells collect metabolic waste products from the overlying photoreceptors.  

Wet AMD is less common but accounts for almost all severe vision loss caused by either type of AMD. Wet AMD occurs when abnormal blood vessels start to grow beneath the retina where they leak fluid and blood and can create a large blind spot in the center of the visual field. If this happens, there is a marked disturbance of vision in a short period of time.

The presence of drusen, tiny yellow deposits in the retina, is one of the most common early signs of AMD. These will be visible to your doctor during an eye examination. While the presence of drusen alone does not indicate the disease, it may mean the eye is at risk for developing more severe AMD.

In addition to a complete medical history and eye examination, your eye care professional may perform a visual acuity test and a pupil dilation to diagnose AMD. In detecting wet AMD, other tests may be used: Amsler grid, optical coherence tomography,  and fluorescein angiography.

  • In the Amsler grid test, a checkerboard-like grid is used to determine if the straight lines in the pattern appear wavy or missing to the patient—both indications may signal the possibility of AMD.
  • Optical coherence tomography is a high resolution ultrasound image of the macula. It is used to measure retinal layer thickness to determine if fluid (macular edema) is present and used to monitor patient response to treatment.
  • Fluorescein angiography involves a special dye injected into a vein in the arm. Pictures are then taken as the dye passes through the blood vessels in the retina, helping the doctor evaluate if the blood vessels are leaking and whether or not the leaking can be treated. 

Treatment for wet AMD may include one type of laser surgery in which a high energy beam of light is aimed directly onto the leaking blood vessels to prevent further leaking. Painless injections of biologic medicines can halt the growth of new blood vessels.

Currently, there is no treatment for dry AMD. This does not, however, indicate that sight will automatically be lost, particularly if the AMD affects only one eye. Central vision may eventually be lost or diminished, but generally the rate of loss is slow.

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Medical Reviewers: William C. Lloyd III, MD, FACS Last Review Date: Apr 9, 2017

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Medical References

  1. Facts About Age-Related Macular Degeneration. National Institutes of Health. National Eye Institute. https://www.nei.nih.gov/health/maculardegen/armd_facts
  2. Macular Degeneration. MedlinePlus, U.S. National Library of Medicine.  https://medlineplus.gov/maculardegeneration.html

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