Macular Degeneration
MACULAR DEGENERATION
MACULAR DEGENERATION
What is Macular Degeneration?
What is Macular Degeneration?
Macular degeneration is a disease that affects the inside part of your eye responsible for central vision. It progresses very slowly, resulting in a central blind spot over the course of several decades. Its formal name is “Age-related macular degeneration” or AMD because it is related to aging. In the United States, it is the most common cause of vision loss in people over the age of 50.
AMD is classified as either wet (neovascular) or dry (non-neovascular) AMD. About 10% of patients who suffer from macular degeneration have wet AMD. During a retina examination and with testing your doctor will be able to tell you which type you have.
What causes macular degeneration?
There are many factors that lead to the presentation and formation of age related macular degeneration and not all of it is completely understood. What we know so far is that as the eye processes light there is left over debris that gets recycled. Over time the recycling system of the eye starts to slow down and the debris begins to accumulate and can be seen on exam. Visible deposits of this debris during a retina examination are referred to as drusen. When drusen are identified a diagnosis of “Age-related Macular Degeneration” may be given. The severity of the disease is determined by assessing the size and quantity of drusen and associated changes present during your examination.
What causes vision loss with macular degeneration?
Drusen deposits can cause physical “bumps” in the layers of the retina. This can cause straight lines to bend. We refer to this as metamorphopsias. These visual changes may fluctuate as drusen come and go.
Over time drusen are toxic to the surrounding retina tissue and lead to eventual tissue death. This can be seen on exam as patches of missing retina tissue. This is a later stage of Dry Macular Degeneration and patients will notice a part of the central vision missing that correlates to the patch of tissue loss. Over time this can expand and eventually involve the direct central vision. This is the most debilitating stage of macular degeneration.
What will happen to my sight with macular degeneration?
Macular degeneration varies widely in severity. In the early stages of Dry AMD, it may only cause slight distortion. In the worst cases, it causes a complete loss of central vision, limiting reading or driving impossible. Fortunately, macular degeneration does not usually cause total blindness since it does not affect the peripheral vision.
I have dry AMD, is there anything I can do?
There is currently no treatment available to reverse the effects from Dry AMD. Several years ago a study reported that certain vitamins may help to delay the onset of vision loss during specific stages of the disease. The study was referred to as the AREDS study and there is now a commercially available formula. Many multivitamins contain the same vitamins as were used in this study.
Additionally exercise and a healthy diet of green vegetables can slow down the disease and the onset of vision loss. The most important lifestyle modification that can be made to preserve vision is to avoid smoking. Smoking is by far the single most modifiable risk factor one can change to delay the progression of vision loss from dry AMD.
Lastly, regularly using an Amsler grid to monitor for changes can assist in early detection of wet macular degeneration (See how to use Amsler Grid at end of this article). Reporting changes to your eye care provider can facilitate earlier intervention and subsequent preservation of your vision. It is recommended that you use the Amsler Grid daily one eye at a time.
When vision loss becomes advanced, there are eye doctors that specialize in optimizing the vision you have. We refer to this type of doctor as a low vision specialist. If you or a loved one has limited vision due to dry macular degeneration then a low vision specialist may be able to help you. Ask your primary eye doctor to see if a low vision specialist would be helpful for you.
Amsler Grid
- Use a bright reading light
- Hold the chart approximately 14-16 inches from your eye
- Cover one eye
- Look at the center dot
- Note irregularities (wavy lines, size, gray, fuzzy)
- Repeat the test with your other eye
- Contact an ophthalmologist if you see any irregularities or notice any changes
What is wet macular degeneration?
This type occurs when new vessels form to heal damaged tissue related to Dry AMD. However, the new vessels are very delicate and break easily, causing bleeding and damage to surrounding tissue. When one eye has wet macular degeneration there is about a 25% chance the other eye will become wet in five years.
The medication used to treat Wet AMD is just like any other medication. Consider for example, a person with high blood pressure who is prescribed a new medication. Upon returning to the doctor for a follow up, the blood pressure has returned back to normal. The patient then asks the doctor if he can stop the medication because his blood pressure is better. Unfortunately, for this patient the blood pressure is better because of the medication and it would increase again if the medication was stopped. Now there are examples of patients coming off of their blood pressure medications just as there are examples of patients eventually getting off of their treatment for wet AMD. This generally takes time and is not expected in every case.
As stated earlier, every eye is different and each case of macular degeneration is unique. Treatment is tailored to the specific drug used and the frequency of treatments. The maximum treatment frequency is an injection every four weeks. However, once the disease is controlled the treatment interval can be extended. We refer to this as “treat and extend”. One way to think about this is tapering off the medication: the interval between each treatment is slowly extended. As the interval between your injections increases, eventually there will be subtle changes and signs that indicate the disease is coming back. At this time, your doctor will either increase your injection frequency by one week and hold it at that interval or hold at your current treatment interval depending on what your exam demonstrates. This is referred to as “maintenance” and the goals are to maintain suppression of wet AMD activity.
For some patients, extending the interval between each treatment may not be the best option for vision. During treatment and extension, the interval between treatments is slowly increased until signs of recurrence appear. Then the treatment interval is shortened by one or two weeks and maintained. A patient with profound vision loss from AMD in one eye and getting treated in the other eye may not want to risk having the disease come back in their only good eye and possibly vision loss with extension. There are several other reasons and your doctor may discuss this with you when the time to increase the treatment interval arises. During these situations these patients are often treated at a fixed interval: they get an injection at a fixed interval of time and plan on keeping at that interval for life. This approach is referred to as a “fixed interval” treatment plan.
