Definition:
Age-related macular degeneration (AMD) is one of the most common causes of poor vision after age 60. AMD is a deterioration or breakdown of the macula. The macula is a small area at the center of the retina in the back of the eye that allows us to see fine details clearly and perform activities such as reading and driving.
The visual symptoms of AMD involve loss of central vision. While peripheral (side) vision is unaffected, one loses the sharp, straight-ahead vision necessary for driving, reading, recognizing faces, and looking at detail.
Although the specific cause is unknown, AMD seems to be part of aging. While age is associated with developing AMD, heredity, blue eyes, high blood pressure, cardiovascular disease, and smoking have also been identified as risk factors. AMD accounts for 90 percent of new legal blindness in the US.
Types of AMD:
9 out of 10 people with AMD have the dry form (called atrophic), which results in thinning of the macula. Dry AMD takes many years to develop. Currently there is no treatment for this form of AMD.
The wet form of AMD (called exudative) is less common (occurring in 1 out of 10 people with AMD), but is more serious. In the wet form, abnormal blood vessels may grow in a layer beneath the retina, leaking fluid and blood. This creates distortion or a large blind spot in the center of vision. If the blood vessels are not growing directly beneath the macula, laser surgery is the only proven effective treatment, to date, for wet AMD. The procedure usually does not improve vision but prevents further loss of vision.
For wet AMD patients whose blood vessels are growing directly under macular center, a procedure called photodynamic therapy (PDT) may be used with fewer visual side effects than other treatments.
Promising AMD research is being done on many fronts. In the meantime, high-intensity reading lamps, magnifiers, and other low-vision aids enable people with AMD to make the most of their remaining vision. Find links to more information in our Community Resources section.
Self-test:
The Amsler grid is used to assess macular function. The grid below on the left shows the Amsler grid as seen by a person with normal macular function. The grid on the right is an example of how the grid may appear to a person with macular degeneration.
To perform a self-assessment, print out this Amsler grid (requires Adobe Acrobat Reader) and follow the instructions.
Treatment:
The only treatment for macular degeneration at this time is laser photocoagulation. A laser coagulates the leakage point behind the retina, stopping or slowing leaking to prevent furthur macular degeneration. However, the benefit of this procedure lasts only about a year and is suitable for only about half of patients with wet macular degeneration.
All patients with signs of macular degeneration should take a one-a-day eye vitamin.
More information:
Macular Degeneration Federation, Inc.
Macular Degeneration Partnership