By Kamal Kishore, MD
Macular degeneration, also known as age-related macular degeneration (AMD) is the leading cause of vision loss in people over 60. In the United States, 15 million individuals have AMD. Of these, 1.7 million are legally blind from advanced AMD and that number is likely to increase to 3 million by the year 2020. The prevalence of AMD increases with age affecting approximately 30 percent of individuals 80 years or above.
What is the macula?
If you imagine the eye like a camera, the retina is the film or sensor of the camera. The image of objects is focused on the retina by the front of the eye and is sent to the brain by the nerve of sight known as the optic nerve. The macula is a tiny portion of the retina about the size of a pinhead that is located in the center of the retina and is responsible for reading or driving vision. The rest of the retina gives peripheral or side vision. Any damage to the macula such as that caused by AMD, affects central or fine vision including reading, watching TV or driving.
What causes macular degeneration?
Although the exact cause of AMD is still a matter of debate, it is more common with older age, female gender, individuals with blue eyes, those with a family history of AMD, high cholesterol, obesity, hypertension and diabetes. In addition, smokers have three to six times the increased risk for AMD. Thus, a healthier body, nonsmoking status, and a diet rich in lutein (spinach, collard green, kale) provides protection against AMD.
Types of AMD
Almost all cases of AMD start out as the dry type in which yellow bumps, known as drusen, form over the macula. In time, cells in the macula die leaving behind patches of tissue loss, known as geographic atrophy.
In some patients, abnormal blood vessels form under the macula, which cause leakage of fluid, bleeding or scarring in the macular. This stage, known as the wet AMD, is seen only in 10 percent of patients with AMD, but is responsible for 90 percent of the cases of legal blindness due to AMD.
What are symptoms of AMD?
Many patients with dry AMD have no symptoms. Others may have blurred spots, missing spots, or distortion in reading vision. Generally symptoms from dry AMD are mild and progress slowly over years. Rapid but painless decrease or distortion of central vision overnight or over a few days is the most important symptoms of wet AMD.
How is AMD treated?
Patients with significant dry AMD benefit from eye vitamins. The most current formulation of vitamins to slow down dry AMD is known as AREDS2, named after the study that showed its benefits. Patients with wet AMD are usually treated with injections to stop the bleeding and swelling. Vision can be stabilized in most patients with periodic injections and some patients can actually experience improvement in vision. Generally, patients with better vision at the initiation of treatment have better outcomes underscoring the need for early diagnosis and prompt treatment of wet AMD.
What can I do?
All individuals above 55 should have annual eye exams to detect dry AMD that may require eye vitamins. In the absence of at least moderate dry AMD, there is no benefit from the routine use of eye vitamins. Smokers should try to quit smoking and we all should try to control our medical conditions the best we can. Each one of us should monitor our reading vision by covering one eye and using the other eye by itself while reading at least five minutes a day. If you notice any new areas of distortion, blurriness or dark spots, contact your eyecare provider right away. A simple device, known as an Amsler grid, is another method to keep a watch on your central vision and is available free of cost at our office.
If you would like a FREE Amsler Grid or would like more information, please call the Illinois Retina & Eye Associates in Peoria at 309-589-1880. Dr. Kamal Kishore is a fellowship trained retina specialist providing treatment and surgery for eye diseases such as macular degeneration, diabetic eye disease, retina tears and detachments and problems from previous surgery or injury.
Figures courtesy Illinois Retina and Eye Associates