What Treatments Are Available for Wet Macular Degeneration (AMD)?
In wet (neovascular/exudative) age-related macular degeneration (AMD), abnormal blood vessels develop under the macula and break, bleed, and leak fluid. This damages the macula and if left untreated can result in rapid and severe loss of central vision. The most effective treatments to date for wet AMD are several anti-angiogenic drugs.
Angiogenesis is a term used to describe the growth of new blood vessels and plays a crucial role in the normal development of body organs and tissue. Sometimes, however, excessive and abnormal blood vessel development can occur in diseases such as cancer (tumor growth) and AMD (retinal and macular bleeding).
Substances that stop the growth of these excessive blood vessels are called anti-angiogenic (anti = against; angio = vessel; genic = development), and anti-neovascular (anti = against; neo = new; vascular = blood vessels).
The focus of current anti-angiogenic drug treatments for wet AMD is to reduce the level of a particular protein (vascular endothelial growth factor, or VEGF) that stimulates abnormal blood vessel growth in the retina and macula; thus, these drugs are classified as anti-VEGF treatments.
At present, these drugs are administered by injection directly into the eye after the surface has been numbed. The needle is very small and is inserted near the corner of the eye — not the center. During the injection procedure, the doctor will ask the patient to look in the opposite direction to expose the injection site, which also allows the patient to avoid seeing the needle. Anti-angiogenic drugs currently in use include Lucentis, Avastin, and Eylea. An earlier drug, Macugen, is also used in certain circumstances.
To learn more about clinical research on treatments for macular degeneration, visit the National Eye Institute website for information on clinical studies.
A Word About Clinical Trials for Wet Macular Degeneration
In order to receive approval from the U.S. Food and Drug Administration (FDA), a new drug or treatment must be proven to be both safe and effective by undergoing a rigorous series of controlled unbiased studies. To prevent bias, neither the patient nor the examiners can know which patients received the actual treatment and which were the untreated (or "control") subjects.
These are called "double blind" or "double masked" studies and usually yield the most reliable results. The medication is coded and patients are placed at random into either the treatment or control group. When the study is concluded, the code is revealed and it is then possible to determine who received the actual drug and who received the inactive substance, or placebo.
As defined by the U.S. National Institutes of Health, most clinical trials are designated as Phase I, II, or III, based on the questions the study is seeking to answer:
- In Phase I clinical trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe and effective dosage range, and identify possible side effects.
- In Phase II clinical trials, the study drug or treatment is given to a larger group of people (100-300) to determine if it is effective and to further evaluate its safety.
- In Phase III studies, the study drug or treatment is given to even larger groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
- In Phase IV studies, after the Food and Drug Administration has approved the drug, continuing studies will determine additional information, such as the drug's risks, side effects, benefits, and optimal use.
As the incidence of AMD increases, due primarily to the aging of the US population, a number of in-depth studies, clinical trials, and remedial interventions are presently underway. ClinicalTrials.gov is a website that provides a searchable list of all current clinical trials related to AMD.