December 25, 2016
Macular degeneration is the leading cause of vision loss in the United States, affecting more than 10 million Americans. According to the American Macular Degeneration Foundation (AMDF), that’s more than cataracts and glaucoma combined.
“The central portion of the retina, called the macula, is responsible for the center part of vision. It allows us to focus forward vision, distinguish details and recognize faces, among other things,” said Timothy Tweito, MD, an ophthalmologist specializing in retinal diseases at the Nevada Retina Center and Sunrise Hospital and Medical Center.
Currently an incurable disease, macular degeneration occurs when part of the retina begins to deteriorate, leaving patients with blurred vision, blind spots and eventual blindness.
Though macular degeneration cannot be cured, there are steps that can slow its progression.
There are two types of macular degeneration
Dry macular degeneration describes the deterioration and thinning of the retina’s macula and often is related to age; it’s also referred to as age-related macular degeneration (AMD).
“Dry AMD generally comes on through wear and tear to the retina and gradually affects vision over time,” Tweito said. It tends to progress over the course of years and causes subtle vision impairment in its early stages.
Wet macular degeneration is a much more aggressive form of the disease and can cause vision loss within a matter of days or weeks.
“Wet macular degeneration usually evolves from dry AMD when abnormal blood vessels begin to grow beneath the retina and macula. They then leak blood and fluid into the eye and even cause scar tissue in some patients,” Tweito said.
The leaking of blood and fluid can cause the macula to become permanently damaged, leading to severely distorted central vision and large blind spots. When wet macular degeneration stems from dry AMD, it’s often referred to as wet AMD.
Dry macular degeneration accounts for about 85 to 90 percent of all cases.
Are you at risk?
Age is the qualifying risk factor for macular degeneration, but family history, race and lifestyle can be considerable factors as well.
“Patients who have a family history of AMD can be more prone to developing the disease themselves, especially if a parent or sibling had it,” Tweito said.
Race also plays a role, as Caucasians have a higher instance of developing the disease than African-Americans or Latinos of the same age group. This may be related to differences in genetic makeup and/or pigmentation.
Smoking is the single most controllable risk factor, as it affects oxygen supply to the retina, which can lead to damage and strain on the affected cells. “If you have a family history of AMD and you smoke, you may have 20 times the risk of developing the disease as the general population,” Tweito said.
Diet, activity level and/or obesity:
According to the BrightFocus Foundation, people with poor diets that are high in cholesterol and high-glycemic index foods, and low in antioxidants and leafy greens, may be more prone to AMD. Further, people who have a low activity level may also be at risk because their blood circulation is likely not as good as someone who exercises regularly. Obese patients also are at higher risk; people with a BMI greater than 30 are 2.5 times more likely to develop the disease.
Symptoms and diagnosis
Most people with early-stage AMD will have no or negligible symptoms, and may not realize there is a problem until their vision is blurred or spotty. Regular eye exams can help catch AMD early, allowing patients to begin treatments sooner and slow the progression of the disease before vision impairment occurs. Anyone over the age of 55, and especially those with risk factors, should see an ophthalmologist on an annual or biannual basis.
To diagnose dry AMD, the doctor will dilate your pupils and examine your eyes with an ophthalmoscope. From there, you may be asked to do a series of vision tests to detect vision impairment.
Wet macular degeneration is usually diagnosed after dry AMD has been found. To detect if there’s fluid in the retina, the doctor will conduct a cross-sectional scan of the retina using an imaging technique called optical coherence tomography (OCT).
Another available diagnostic test is called a fluorescein angiography, wherein dye is injected into the arm of the patient, which then travels to the eye, and photographs are taken to detect abnormalities in the retina.
Currently, the only treatment for dry AMD is vitamin supplements. “While this is not a curative treatment, certain vitamins have been proven to reduce the risk of vision loss and slow the progression of the disease,” Tweito said. The supplements contain antioxidants, as well as lutein and zeaxanthin, nutrients that support retina health.
The only effective treatment for wet AMD are medicines injected directly into the eye that aid in removing hormones that contribute to blood vessel growth. There are three commonly used injections: Avastin, Eylea and Lucentis.