How would you feel if you lost your eyesight? When asked this question, nearly half of Americans recently surveyed by researchers at Johns Hopkins University said that it would be the worst possible thing that could happen to their health. Ironically, half of the respondents in the same survey were completely unaware of age-related macular degeneration (AMD), a leading cause of blindness in the US.
THE BASICS OF AMD
The word “age” in AMD doesn’t mean that the condition affects only the elderly. Rather, it means that the incidence of AMD rises with age. The exact causes of AMD are unknown, but some risk factors are well established—such as age, gender (women get it more often than men) and race (whites face a higher risk than other races). Other risk factors: Having blue eyes…obesity…and high blood pressure. A healthy lifestyle that includes not smoking and a nutritious diet are the best ways to help reduce the risk for AMD.
DRY AND WET AMD
AMD affects and damages the macula of the retina—the region of the retina responsible for central vision (seeing what’s right in front of us) and fine acuity vision (seeing fine details).
There are two forms of AMD—dry and wet. The dry form accounts for 90% of people with AMD. In the early stages, dry AMD may cause no visual symptoms, which is why routine eye exams are important for diagnosis. As dry AMD progresses, patients may start to notice subtle changes or distortions in central vision such as straight lines that appear wavy or written words that seem to be missing letters. In the late stages of dry AMD, patients may have severe vision loss. In general, however, the progression of dry AMD is slow and occurs over many years, and some patients may never have vision loss.
Wet AMD is characterized by abnormal blood vessels that grow under and into the retina. The blood vessels can leak blood and fluid that reduce vision and damage the retina. Wet AMD causes the majority of cases of AMD-related blindness and can progress rapidly.
The dry form of AMD can progress to the wet form—risk of conversion from dry to wet AMD is approximately 14% to 20% over five years. There may be no symptoms early in the conversion of dry to wet AMD. Subsequently, patients may notice subtle vision changes such as those described above. Severe vision loss, such as dramatic reduction in overall vision or a large dark area in central vision, can develop, especially if wet AMD goes untreated.
DIAGNOSIS OF AMD
Because most people with dry AMD may have no symptoms, regular eye exams are important to identify the early signs of the disease. AMD can be diagnosed during a routine dilated eye exam done by an ophthalmologist or optometrist. The American Academy of Ophthalmology advises a baseline eye exam at age 40 (earlier if you have eye disease or are at risk for developing eye disease) and an exam every year or two at age 65 and older. However, your doctor may advise more frequent exams based on your specific situation.
If you experience any slowly progressive (over weeks or months) vision changes, get promptly evaluated by an ophthalmologist. And if you have severe and sudden vision loss, see an eye doctor immediately, preferably on the same day, for an evaluation to determine if you need emergency treatment.
TREATMENT FOR DRY AMD
If you have dry AMD, there are currently no medical treatments, but it can be effectively managed to prevent progression. What to do…
• Maintain a healthy lifestyle—don’t smoke and eat a nutritious diet.
• Get an eye exam once or twice yearly, including an optical coherence tomography scan to check for progression from dry to wet AMD. This noninvasive imaging test allows doctors to examine the retina to detect the abnormal blood vessels of wet AMD at very early stages. Your doctor may repeat the test at every visit. The test is also used to monitor wet AMD.
• Self-monitor. Use the Amsler grid—with horizontal and vertical lines—at least a few times a week to check for subtle vision changes in each eye. If there’s any change in the grid when looking at it, such as straight lines that appear crooked/wavy or parts of the grid are missing, you should contact your eye doctor. A downloadable Amsler grid is available at AmslerGrid.org, and grids are also available as a smartphone app.
Also: For some patients, getting the right nutrients may prevent dry AMD from worsening. An eye doctor can tell you if your situation warrants vitamins for your eyes.
What the research shows: A large clinical trial led by the National Institutes of Health found that patients with intermediate or advanced AMD in only one eye who took an antioxidant mix—500 mg of vitamin C…400 international units (IU) of vitamin E…15 mg of beta-carotene…80 mg of zinc…and 2 mg of copper (known as the AREDS formula)—were less likely to have progression of AMD.
Note: Current or former smokers should use the newer AREDS2 formula, which has lutein and zeaxanthin instead of beta-carotene—beta-carotene is associated with increased risk for lung cancer in smokers.
These mixes are available over-the-counter in pharmacies.
Previously, the average patient with wet AMD quickly lost significant vision (two to three lines on the vision chart in the first two years alone). But with the advent of anti-vascular endothelial growth factor (VEGF) therapy, vision can be stabilized or improved in roughly half of patients.
Multiple large clinical trials have demonstrated that intravitreal injection (into the eye) of medications that block VEGF, such as bevacizumab (Avastin) and aflibercept (Eylea), dramatically reduce vision loss in wet AMD.
The procedure is done with local anesthesia in the ophthalmologist’s office. It’s quick and usually painless. The injections are often given monthly…or on a less frequent basis, depending on how the patient is doing. Some people need long-term therapy, while others can over time reduce or discontinue it but are monitored closely as many patients subsequently need additional treatments (when the wet AMD becomes active again). The treatment controls wet AMD but is not a cure. The risk associated with injections is very low but includes cataracts, retinal detachment, bleeding or infection/inflammation in the eye.