The goals of the treatment of wet macular degeneration are much the same as cancer treatment. By making the analogy to tumors, treatment for the “wet” form of the disease may be simpler to understand.
Tumors and Neovascularization
In the retina, the “wet” form of macular degeneration refers to the growth of a clump of abnormal blood vessels. Some doctors call this a “membrane.”
Let’s pretend it is a tumor. It behaves the same way.
Like a tumor, wet macular degeneration takes up space. It occupies space within the layers of the retina. In addition, these abnormal blood vessels leak causing a puddle of fluid to accumulate around the clump of vessels. The combination of the wet macular degeneration and its surrounding fluid effects the retina and vision by the amount of space taken.
Symptoms of macular degeneration include blurry vision and distortion. In the wet form, much of the distortion is caused by physical separation of the layers of the retina. This “tumor-like” growth creates an uneveness within the layers of the retina just like the “Princess and the Pea.” An uneven retina causes distortion. The physical separation (along with degeneration) of the layers of the retina also cause blurry vision.
Goal #1: Treating Early
If we view the abnormal blood vessels as a tumor, a small tumor causes a small effect and a larger tumor causes a bigger effect. A small clump of neovascularization has a smaller effect on vision than a larger one.
Thus, we want to diagnose and treat wet macular degeneration early.
We want to limit the size and extent of the loss of vision by limiting the size of the neovascularization.
Early treatment is aimed at preserving as much vision as possible. This is why you see your doctor with persistent changes in vision and use an Amsler grid. This self-monitoring of your vision increases the chances of treating your wet macular degeneration early.
Goal #2: Improving Vision
A second goal of treatment is to improve vision. One way to assess the success of the macular degeneration treatment is to determine improvement of vision. Again, some of the vision loss caused by wet macular degeneration is by space it takes up in the retina.
If the cluster of abnormal blood vessels can be made smaller, there is less of a physical disruption to the retina. Many times, vision improves just by getting the lesion to shrink and stopping the vessel leakage. It takes up less room.
Similarly, tumors are “space occupying lesions.” A cancer treatment is deemed effective based upon its ability to “shrink” the tumor. As the tumor shrinks symptoms may abate.
Treatment for wet macular degeneration includes eye injections of anti-VEGF medications. These drugs (Avastin, Lucentis, Macugen) all work by shrinking the clump of neovascular vessels and stopping the leakage. We have found that an effective way of shrinking this “tumor-like” complex is by prescribing a series of these intraocular injections.
Goal #3: Maintaining the Vision
The third goal of treatment is to achieve and maintain stability of the vision. To say another way, we don’t want the wet macular degeneration to regrow and leak again.
How? We monitor for growth, or recurrence, of the wet macular degeneration. Return visits to the office are really checking for signs and symptoms of recurrence of the wet macular degeneration. We monitor your vision and may test you with an OCT and/or fluorescein angiogram looking for signs of recurrence.
Just like cancer treatment, tumors are monitored for signs of growth. Instead of a fluorescein angiogram, an ultrasound, CT scan or MRI my be used. If the tumor shows signs of enlarging, retreatment is considered.
What Does This Mean? By making the analogy to a tumor, much of wet macular degeneration treatment can be easier to understand. Both the tumor and wet macular degeneration cause damage by the physical space it occupies. There is a direct correlation to size of the lesion and symptoms, the smaller the lesion, the fewer the symptoms. In another way, the smaller the wet macular degeneration, the better the vision.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
Fairfax, Virginia
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