We’ve come a long way in our understanding and treatment of age-related macular degeneration (AMD), the leading cause of vision loss for people ages 50 or older in the United States. We’ve learned that certain genes and lifestyle factors increase the risk for developing AMD, and discovered treatments that often slow the disease’s progression.
Yet for all our advances, we still don’t have a guaranteed way to prevent AMD. You are at greater risk if one of your parents had the condition. “One needs to be concerned, but it doesn’t mean you’re destined to get it. It’s a complex disease, and it takes a combination of factors for it to develop,” says Dr. Joan W. Miller, chief of ophthalmology at Harvard-affiliated -Massachusetts Eye and Ear and ophthal-mology chair at Harvard Medical School.
What is AMD?
AMD destroys the macula — the central part of the retina, the layer of tissue in the back of the eye that changes light into electrical signals. The signals are sent to the brain, which converts them into images.
There are two types of AMD. Both types reduce the clarity of central vision, blurring or even erasing the image in the center of a person’s vision.
In dry AMD, the most common form, deposits of fat and protein called drusen slowly accumulate behind the retina, causing it to thin and leading to the destruction of the macula’s light-sensitive (photoreceptor) cells. The result is vision loss.
As AMD progresses, drusen can cause new, abnormal blood vessels to grow under and into the macula. The blood vessels leak and bleed, rapidly causing photoreceptor cell damage, scarring, and vision loss. This is called wet AMD.
Our ability to treat both forms of AMD varies.
We can sometimes slow dry AMD. Dr. Miller says the best approach we have is a cocktail of antioxidant nutrients (vitamins C and E, copper, lutein, zeaxanthin, and zinc) called the AREDS2 formula (named for a study of the nutrient regimen in people with AMD). The components of AREDS2 fight free radicals, abundant molecules in the retina that cause oxidative stress (which can damage proteins and DNA within cells). Studies have shown that AREDS2 may reduce dry AMD progression by 25%.
We can do much more to stop wet AMD. The most effective treatment so far is anti-VEGF therapy (short for antivascular endothelial growth factor therapy), pioneered by Dr. Miller and her colleagues. VEGF is a molecule that causes tiny new blood vessels to grow — sometimes in places where they are not needed (like the macula). In anti-VEGF therapy, doctors inject medications into the eye that block the effects of VEGF. This can reduce blood vessel leakage, prevent new blood vessel growth in the eye, and even restore some lost vision.
Another option for wet AMD is laser surgery to seal leaky blood vessels in the eye.
Hope for future treatments
Many other approaches to treat AMD are currently being studied or considered for study.
Stem cell therapy. This treatment replaces damaged retinal cells with stem cells that will turn into replacement retinal cells.
Gene therapy. This approach introduces new genes into the eye to help the retina produce proteins that stop abnormal blood vessel growth.
Statin therapy. Statins — drugs that lower cholesterol levels and reduce inflammation — also may be able to pull bad fats out of the retina. “We did a small pilot study that showed large drusen disappeared in nearly half of the patients with AMD who took a high-dose statin, and no one progressed. It was only 10 out of 23 patients. But now we’re interested in investigating that further,” Dr. Miller says. “The notion is that you could turn back the clock and sets things back by a decade.”
Fixing the retina’s “autophagy.” Autophagy is a natural process by which cells clear away waste or damaged material inside them. “It doesn’t work well in retinal cells when people have AMD. We and others are currently studying this,” Dr. Miller says.
Fighting inflammation. “It could be that fats collect in an abnormal way which stimulates a chronic inflammatory reaction that’s destructive to the tissues,” Dr. Miller says. “Several groups are studying this.”
Targeting the immune system. A part of the immune response called the complement cascade may mistakenly damage the retina. This may play a role in AMD. Several drugs that inhibit the complement cascade are being studied.
These approaches are preliminary and may not pan out. But they offer a reason for hope. “Drug development takes a long time. It may be a decade before we have another treatment,” Dr. Miller notes, “but it may be sooner.”
For now, the only advice to ward off AMD is to follow healthy lifestyle habits that help reduce your risk for the eye disease — and for many other health problems as well.
Don’t smoke. Smoking has many damaging effects on the body, including increased oxidative stress in the retina. “Oxidative stress may affect the way the blood vessels respond,” Dr. Miller says, “and there seems to be some interaction between smoking and genes that can increase your risk for developing AMD.”
Control your blood pressure. High blood pressure damages your blood vessels and increases your risk for AMD. “We want healthy blood vessels in the eye; they feed the retina nutrients and oxygen, and they cool the eye and keep it from overheating as retinal cells turn light into electrical signals,” Dr. Miller says.
Exercise. Exercise keeps your blood vessels healthy. Aim for at least 150 minutes per week of moderate-intensity exercise, such as cycling, swimming, or brisk walking.
Eat a heart-healthy diet. Coronary artery disease, high cholesterol, and obesity all increase your risk for developing AMD. Eat a heart-healthy Mediterranean-style diet that includes lots of fruits, vegetables, whole grains, legumes, nuts, seeds, and olive oil; moderate amounts of fish and poultry; and a little bit of low-fat dairy.
Make sure you include green, leafy vegetables; they’re rich in lutein and zeaxanthin, which have antioxidant properties and have been shown to improve pigment density in the macula, which protects the cells from free radicals.
|Age-related macular degeneration risk factorsWhile it’s not clear exactly what triggers age-related macular degeneration, we do know that these factors increase your risk for developing the condition:a family history of AMDage over 50being Caucasianeating a diet high in saturated fatfarsightednessheart diseasehigh blood pressurehigh cholesteroloverweightsmoking|
Don’t forget eye exams
One of the best ways to save your vision is to detect eye disease early.
The American Academy of Ophthalmology recommends exams every two to four years for people ages 40 to 55; every one to three years for people ages 55 to 65; and every one to two years for people ages 65 or older. You may need more frequent eye exams, depending on your health and risk factors.
For more information, see the Harvard Special Health Report The Aging Eye (www.health.harvard.edu/ae).
Bible verses for today’s meditation and inspiration: Matthew E. McLaren
And so we know and rely on the love God has for us. God is love. Whoever lives in love lives in God, and God in them. 1 John 4:16 NIV
Be completely humble and gentle; be patient, bearing with one another in love. Ephesians 4:2 NIV
We love because He first loved us. 1 John 4:19 NIV
Above all, love each other deeply, because love covers over a multitude of sins. 1 Peter 4:8 NIV
I pray that out of his glorious riches he may strengthen you with power through his Spirit in your inner being, so that Christ may dwell in your hearts through faith. And I pray that you, being rooted and established in love. Ephesians 3:16-17 NIV
And now these three remain: faith, hope and love. But the greatest of these is love. 1 Corinthians 13:13 NIV
Love must be sincere. Hate what is evil; cling to what is good. Romans 12:9 NIV
If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but do not have love, I am nothing. 1 Corinthians 13:2 NIV
Recommended contacts for prayer request and Bible study