Macular Degeneration
This is what you may see when you have age-related macular degeneration.
The macula is a small spot in the central area of the retina located at the back of the eye. When the macula is damaged by AMD, the center of the visual field may become blurred, distorted or develop a blind spot.
What is age-related macular degeneration?
The initials AMD are an abbreviation for a disorder called age-related macular degeneration. AMD is a common cause of vision loss in the U.S. and usually strikes people over the age of 60. Few cases occur among persons under 60. After this age, the frequency of the disease rises dramatically.
AMD is a degenerative disease that affects the macula, a small spot in the central area of the retina located at the back of the eye. The macula is responsible for sight in the center of the field of vision and is the most sensitive part of the retina.
When a large amount of central vision is lost, people may find it very difficult to do simple, everyday activities that require sharp vision, such as reading, sewing, driving or recognizing faces. Fortunately, AMD almost never results in complete blindness since side vision is usually not affected.
Most people can maintain their independence and should be able to see well enough to perform most household chores.
AMD can progress rapidly or slowly, The disease usually affects one eye first and then the other.
There are two forms of AMD: wet (exudative) and dry (non-exudative). Though less common, the wet form is responsible for the majority of severe vision loss due to AMD. It is called “wet” because tiny blood vessels begin to grow rapidly beneath the retina, and often break and leak blood and fluid. This distorts vision and causes scar tissue to form.
The “dry” form is caused by a breakdown or thinning of the tissues in the macula. It is very common, accounting for 70 percent to 80 percent of the cases of AMD. Vision loss with dry AMD tends to be moderate.
How is AMD detected?
As AMD progresses, symptoms will become more and more obvious. If you have AMD, you may notice that:
• straight lines in your field of vision-such as telephone poles, the sides of buildings or streetlight posts-appear wavy;
• type in books, magazines and newspapers appear blurry; and
• dark or empty spaces may block the center of your vision.
If you or someone in your family is diagnosed with AMD, it is important to check the central vision separately in each eye daily and report any changes to your eye doctor. These changes may include:
• difficulty in reading
• distortion of straight lines
• abnormal findings on the Amsler Grid.
The Amsler Grid is a cross-hatched pattern of straight lines. To someone whose central vision is deteriorating,the pattern of lines will look blurred, distorted or discolored.
AMD can also be detected through an eye examination by an eye doctor.
If you have had a professional eye exam within the past few years (during which the eye doctor dilated your eyes), you probably have been checked for AMD. An eye doctor can detect the disease, as well as certain changes in the eye that indicate a risk of developing AMD.
One such change is the appearance of small, yellowish deposits at the back of the eye called drusen. Drusen do not generally interfere with sight to a significant degree.
Who is likely to develop AMD?
Age-related macular degeneration is the leading cause of visual impairment for persons age 75 and older. It is the most common cause of new cases of visual impairment among those over age 65.
AMD may be associated with arteriosclerosis, hereditary factors, eye trauma or other conditions that are not yet clearly understood.
How is AMD treated?
Currently there is no medication to control or prevent AMD. Some people with wet AMD can be helped with laser treatment. But for these patients, the disease must be detected at the earliest stages for treatment to be successful.
In laser therapy, a beam of intense light passes harmlessly through the lens of the eye to the retina, sealing off the leaking blood vessels at the back of the eye. This procedure can stop the spread of the abnormal blood vessels. Laser treatment involves minimal discomfort and does not require hospitalization.
Many people who lose some vision due to AMD can often enhance the sight they have left through low vision devices. Your eye doctor or local Friends For Sight office can refer you to low-vision centers.
Why is early diagnosis so important?
Sometimes as AMD progresses, the new growth of tiny blood vessels will invade the macula. Laser therapy is not as effective once the leaky, new blood vessels have grown too near to the center of the macula, where there is a concentration of light-sensitive nerve tissue called the fovea. This is why advanced cases of wet AMD are likely to be untreatable. Sometimes this wet type of AMD progresses very rapidly, so self-testing central vision every day, including use of the Amsler Grid, is essential to help reveal progression of the condition.
How can I test my own vision?
Testing yourself or others is easy with the Amsler Grid. While keeping one eye covered, look at the dot in the middle of the grid. Do the lines appear wavy or distorted? Are any lines missing? If so, this could be a symptom of AMD or some other visual problem. You should discuss any symptoms with your eye doctor as soon as possible.
