Dry Macular Degeneration
What Is Dry Macular Degeneration?
There are two types of age related macular degeneration (AMD): Wet AMD and dry AMD. Dry AMD occurs when the photoreceptors and their supporting cells in the eye gradually break down, resulting in blurred central vision. Over time, you may begin to notice the blurring, or you may realize that you need additional lighting to read or do detailed work.
Dry AMD is the most common form of macular degeneration. According to the National Eye Institute, 90 percent of people who have AMD have the dry form. Although it generally affects both eyes, it can affect one eye more than the other.
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During a dilated eye exam, the earliest sign of AMD which are called “drusen” can be detected. Drusen are yellow deposits which are located under the retina. While scientists know that drusen alone do not cause dry AMD, studies have shown that an increase in the size or number of drusen increases your risk of developing AMD.
Dry AMD occurs in three stages:
Stage 1
In the earliest phase, you may either have several small or a few medium-sized drusen. At this stage, you will usually not have any symptoms or vision loss. |
Drusen
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Stage 2
With intermediate AMD, you may have many medium size or larger drusen. At this point, you may begin to notice some distortion or a blurred spot in your central vision, or you may realize that you require additional lighting to read.
With intermediate AMD, you may have many medium size or larger drusen. At this point, you may begin to notice some distortion or a blurred spot in your central vision, or you may realize that you require additional lighting to read.
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Stage 3
As the disease progresses into advanced AMD, there will be a breakdown in the photoreceptor cells along with the supporting tissue in the retina. This will likely cause a blurred spot or distortion in your central vision, something which may grow darker or larger over time. If AMD primarily affects one eye, you may not be aware of the problem at all. Your other eye will compensate and you may be able to do all of your routine activities, such as reading or driving without difficulty. For this reason, having routine comprehensive eye examinations is important for early diagnosis.
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Blurring of Central Vision
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Although dry AMD does not always turn into wet AMD, if you have wet AMD, you will have had the dry form first. Dry AMD can turn into wet AMD, even in its early stages. Therefore, if you have been diagnosed with drusen or with early stage dry AMD, it is important that you regularly monitor your vision at home using the Amsler Grid.
Appearance of Amsler Grid with Normal Vision
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Appearance of Amsler Grid with AMD
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Photo Credit: National Eye Institute, National Institutes of Health
Your doctor will give you a copy of the grid. When you get home, hang the grid on your refrigerator, bathroom mirror or wall, away from your windows but in an area with good, ambient light. The black dot in the center of the grid should be at eye level. Use a tape measure or ruler, and mark a spot 14 inches from the grid. Since you’ll be using this spot regularly, we recommend that you mark the spot on the floor with tape.
Wearing your normal reading glasses or contact lenses, stand with your heels on the tape and face the grid. Focus on the dot in the center of the grid. Cover your right eye with a piece of paper, and keep looking at the dot. You should be able to see the four corners of the grid. If any of the lines appear wavy or blurry, make a note of this. Next, do the same thing with your left eye.
We recommend that you do this self-examination once a week. You may want to make notes about the results in a small notebook to discuss when you next see the doctor. He will schedule regular dilated exams to monitor changes in the macula. However, if you notice a rapid increase in distortion on the Amsler Grid, you should re-schedule your appointment and come in sooner.