Macular degeneration (also called AMD, ARMD, or age-related macular degeneration) is an age-related condition in which the most sensitive part of the retina, called the macula, starts to break down and lose its ability to create clear visual images. The macula is responsible for central vision – the part of our sight we use to read, drive and recognize faces. So although a person’s peripheral vision is left unaffected by AMD, the most important aspect of vision is lost.
AMD is the leading cause of vision loss and blindness in Americans of ages 65 and older. And because older people represent an increasingly larger percentage of the general population, vision loss associated with macular degeneration is a growing problem. It’s estimated that more than 1.75 million U.S. residents currently have significant vision loss from AMD, and that number is expected to grow to almost 3 million by 2020.
Two Forms of AMD
Macular degeneration can be classified as either dry (non-neovascular) or wet (neovascular). Neovascular refers to growth of new blood vessels in an area, such as the macula, where they are not supposed to be. The dry form of AMD is more common – about 85% to 90% of all cases of macular degeneration are the dry variety.
Macular Degeneration Signs and Symptoms:
Macular degeneration usually produces a slow, painless loss of vision. Early signs of vision loss associated with AMD can include seeing shadowy areas in your central vision or experiencing unusually fuzzy or distorted vision. In rare cases, AMD may cause a sudden loss of central vision. An eyecare practitioner usually can detect early signs of macular degeneration before symptoms occur. Usually this is accomplished through a retinal examination.
Causes of Macular Degeneration?
Epidemiologic studies have indicated that low plasma concentrations and limited dietary intake of carotenoids (organic pigments such as lutein, zeaxanthin and mesozeaxanthin which serve as an optical filter for UV & blue light that damages the macula) are correlated with an increased incidence of macular degeneration. Additionally, cigarette smoking, obesity (BMI>30), poor diet, oxidative stress, fair complexion and advanced age decreases carotenoid concentration in the macula, thus increasing an individual's risk for macular degeneration. AMD has the strongest genetic contribution of all human multi-genetic diseases. Research suggests this gene deficiency may be associated with almost half of all potentially blinding cases of macular degeneration. A currently available validated genetic test (Artic Dx) http://www.macularisk.com/ may provide greater insight into an individual's future risk.
Who Gets Macular Degeneration?
Besides affecting older individuals, AMD appears to occur in whites and females in particular. The disease also can result as a side effect of some drugs, and it appears to run in families. New evidence strongly suggests that smoking increases the risk for macular degeneration 2 1/2 times. Other risk factors for AMD include having a family member with AMD, high blood pressure, lighter eye color, and obesity. Some researchers believe that over-exposure to UV sunlight, and a high-fat and carbohydrate diet also may be a risk factor.
There is as yet no outright cure for macular degeneration, but some treatments may delay its progression or even improve vision. There are no FDA-approved treatments for dry AMD, although nutritional intervention may be valuable in preventing its progression to the more advanced, wet form (see Vitamins/Nutrition tab). A new genetic test, Macula Risk by Artic Diagnostics Inc. http://www.macularisk.com/, can with 83% accuracy help identify patients who are at the highest risk for developing AMD. A healthy diet, physical excercise, and not smoking significantly decreased the risk for dry and wet AMD. For wet AMD, there several FDA-approved Anti-VEGF drugs such as Avastin, Eylea, Macugen, and Lucentis, that are aimed at stopping abnormal blood vessel growth and vision loss from the disease. All the Anti-VEGF drugs work well but the cost of Luccentis and Eyelea is approximately 40x more expensive than Avastin. In some cases, laser treatment of the retina may be recommended.
The treatment of macular degeneration is an area of active research. Numerous compounds administered by various delivery routs and acting via a variety of mechanisms are under investigation in clinical trials. There are variety of additional investigational agents being evaluated for dry and wet macular degeneration. http://clinicalstudies.info.nih.gov/index.html
Testing and Low Vision Devices:
Although much progress has been made recently in macular degeneration treatment research, complete recovery of vision lost to AMD probably is unlikely. Your eye doctor may ask you to check your vision regularly with an Amsler Grid – a small chart of thin black lines arranged in a grid pattern. AMD causes the line on the grid to appear wavy, distorted or broken. Viewing the Amsler grid separately with each eye helps you monitor your vision loss.
If you have already suffered vision loss from AMD, low vision devices including high magnification reading glasses and hand-held telescopes may help you achieve better vision than regular prescription eyewear. The eREADERS available from a verity of vendors and book stores is an inexpensive and effective alternative to the more expensive magnification devices. They allow the reader to increase text size, contrast, and background illumination. There is also an implantable telescope that is now available if appropriate. http://www.centrasight.com/
RESOURCE: American Council of the Blind & Visually Impared of Colorado (ACBCO),1536 Wynkoop St., #201,Denver, CO 80202. 303-831-0117 or 1-888-775-2221 http://www.acbco.org/.
ACBCO is a non-profit organization that provides free non-medical services (home assessments, small adaptive aids, support groups, and referral to other agencies) to help people who are blind or vision impaired of all ages adjust to their vision loss and access resources that will help them remain independent. They partner with many local agencies to accomplish this, including the Colorado Department of Vocational Rehabilitation, the Colorado Talking Book Library, and the Center for People With Disabilities.