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WELL Duquesne University Mylan School of Pharmacy
UPDATE from the Center for Pharmacy Care
March - April 2007
Don’t lose sight of
Macular Degeneration
A
ge-related macular degeneration (AMD) is a troubling vision problem affecting more than 10 million Americans. It is the leading cause of vision loss in people 60 years of age and older. Those afflicted with this disease will experience a decline in central vision so severe they may not be able to recognize faces. Central vision is crucial for seeing clearly and performing routine daily tasks such as reading and driving. AMD usually develops gradually and painlessly and cannot be cured. It is caused by damage to the macula, an area located in the back of the eye and in the center of the retina (See Figure 1). The macula is comprised of densely packed light sensitive cells called cones and rods. As the cells deteriorate, there is a noticeable and progressive loss of vision. There are two forms of this condition identified as wet or dry AMD. The dry form is more common, less severe, and responsible for more than 85% of cases. Dry AMD usually develops in both eyes, although it is possible that vision loss will only occur in one. There are three stages of dry AMD: early, intermediate, and advanced. Early dry AMD lacks symptoms and begins with a breakdown in the eye’s ability to clear naturally
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Figure 1:
Diagram of the Eye
National Eye Institute. Diagram of the eye. 2006 http://www.nei.nih.gov/health/eyediagram/ (accessed 22 Jan 2007)
produced cellular waste known as drusen. As the disease progresses to the intermediate stage, those affected may have a blurry spot in their central vision and require more light for reading. When a person develops advanced dry AMD, there is a breakdown in the light-sensitive cells in the macula as well as significant accumulation of drusen. The blurred spot in the central vision may become
larger and darker resulting in profound disturbances in eyesight. Sometimes dry AMD can progress to the wet variety. This type advances more rapidly and accounts for 90% of the severe vision loss associated with AMD. It is caused by the formation and growth of abnormal blood vessels that leak fluid beneath the retina and macula. It manifests as dark spots in the center of a person’s vision and distortion due to pressure on the eye. Additionally, many affected individuals suffer from hallucinations including strange patterns, geometric figures, animals, and grotesque-appearing faces. This phenomenon is known as Charles Bonnet syndrome. It is not a symptom of mental illness.
Risk Factors The reason people develop AMD is not completely understood; however, age is the primary risk factor. Those over 60 are at the greatest risk for this disease. It has been determined that cigarette smoking doubles a person’s risk of AMD. Researchers have discovered genes associated with AMD; therefore, there is a greater risk for those with a positive family history. Whites tend to develop continued on back
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Don’t lose sight of Macular Degeneration AMD more often than other groups and women appear to be at more risk than men. Some other risk factors include obesity, light-colored eyes, farsightedness, and deficiency in vitamins and minerals such as A, C, E, zinc, and copper.
Screening and Diagnosis A simple examination by your eye doctor is needed to diagnose AMD. The doctor will be looking for changes in the coloring of the macula as well as the accumulation of drusen. It is unknown what relationship exists between drusen and AMD because vision loss is not dependent on its presence. In addition, your doctor may test your eyesight by having you look at grid. If you see any distortion, this allows the doctor to determine the exact location and extent of the disease. Other methods for screening include the use of computer imaging to photograph the inside of your eye. This detects changes in the structure of the eye. It can also be used to monitor response to treatments for AMD. A more invasive screening tool is angiography in which a dye is injected into your arm and photos are taken to evaluate the condition of the eye.
Treatment Options While dry AMD makes up a majority of cases, treatment is only available for wet AMD. Clinical trials are on-going to identify any possible future therapies for dry AMD. Certain vitamin formulations high in concentrations of the anti-oxidants A, C, and E as well as the minerals copper and zinc (for example Ocuvite®, Preservision®, ICaps®, etc.) may benefit patients diagnosed with intermediate or advanced disease (dry form) or wet AMD by reducing the risk of further vision loss. Other anti-oxidants such as lutein and zeaxanthin are still being evaluated to determine their role in treatment. While damage caused by AMD is irreversible, available treatment options may reduce progression of the disease. The success of such treatments is dependent on the location and extent of the disease. High powered lasers can seal fluid leakage and prevent the development of excessive blood vessels. This procedure can
only be used if existing damage is not directly in the center of the macula. Although not recommended for most patients, this type of laser therapy may reduce progression of the disease. Patients who are candidates for this treatment, especially if the AMD is only in one eye, can adequately compensate and may no longer notice any blank spots in their vision. If you have a grey or dark spot in your central vision before this procedure, one risk is that the area will become permanently blank. If the damage to your eye is directly at the center of your macula, photodynamic therapy (PDT) can be performed. The procedure involves the use of a light-activated drug called verteporfin (Visudyne®) that accumulates in your macula after intravenous injection. The drug’s action is triggered by a cold laser resulting in closure of excess blood vessels and prevention of their further growth. Due to the nature of this drug, you must avoid sunlight and bright lights for about 5 days. Additional treatment options include medications that can be injected directly into the eye (intra-vitreal injection) to prevent the formation of new blood vessels and leakage from existing ones. The only available medications of this type are ranibizumab (Lucentis®) and pegaptanib (Macugen®). They are administered every 4 or 6 weeks respectively. Bevacizumab (Avastin®) has also been used for AMD, but is not labeled for this indication by the FDA. While these medications are effective, they are expensive ($500 to $2000 per dose) and must be used for an extended period to prevent further deterioration in vision.
Newsletter Contributors John G. Lech, Pharm.D. Michael R. Schmitt, Pharm.D. Candidate Renee R. Tis, Pharm.D. Candidate
For additional information, please visit the following Web sites: • http://www.amd.org • http://www.mayoclinic.com/health/macular-degeneration/DS00284 • http://www.nei.nih.gov/health/maculardegen/armd_facts.asp
Measures to Lower Your Risk of AMD ●
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DIET Get your daily requirements of antioxidants. Vitamin A, C, E, lutein, and zeaxanthin are found in a variety of fruits and vegetables. People who eat green, leafy vegetables combined with a low-fat diet may have a lower risk of AMD. Fish are high in omega-3 fatty acids and can reduce the risk of AMD. LIFESTYLE Wear sunglasses that block out harmful ultraviolet light. Stop smoking. People who smoke are at higher risk for developing AMD. Take care of other medical conditions such as high blood pressure and diabetes. SCREENING Get regular eye exams. AMD is irreversible so catching it early can drastically improve your chances of preventing vision loss. If diagnosed with AMD, have your vision screened regularly and report any changes to your eye doctor.
Macular degeneration is an increasingly diagnosed condition that can result in loss of vision. Treatment options are limited and consist of possible surgery and drug therapy. A balanced diet, healthy lifestyle, and proactive approach to eye care can greatly reduce your risk of developing AMD and/or progression of the disease.
A publication of the Duquesne University Mylan School of Pharmacy Center for Pharmacy Care & Pharmaceutical Information Center (PIC) Additional information on any of the topics discussed may be obtained from the Pharmaceutical Information Center by calling 412-396-4600 or sending an e-mail to pic@duq.edu. Questions about screenings or programs: Christine O’Neil, Pharm.D, B.C.P.S., 412-396-6417 3/07 314557 CG