Published February 21, 2007
The eyes have it in our culture, so anything that threatens our vision can put a real damper on our lives. Though eye care should begin before the eighth decade of life, many eye troubles do occur at this age, including age-related macular degeneration, or AMD, for short.
This devastating eye disease affects about a third of the Caucasian population age 75 and older. AMD is the leading cause of legal blindness among Caucasians, though it is, quite curiously, rather rare in other races.
Macular degeneration damages the center of the retina, the tissue that converts optical images to electrical impulses, which then travel to the brain via the optic nerve. Since this degenerative condition affects only the central vision, it leaves the peripheral vision intact, so it doesn’t cause total (or “cane”) blindness.
To get an idea of what you are left with in terms of vision, hold your thumbs upright and close to the front of your eyes. That’s all those with MD can see. And you can’t see around the thumbs, as the impairment follows you around as you move your head. In short, it’s pretty debilitating.
The Heredity Factor
New scientific research suggests that genes may play a significant role in the development of macular degeneration. Scientists have identified two genes that appear to be strongly associated with a person’s risk for developing AMD. Three out of four people with AMD carry variants of the Factor H and Factor B genes, as they are known; these genes are responsible for proteins that help regulate inflammation in the part of the immune system that attacks diseased and damaged cells.
Scientists have also identified a gene on chromosome 10, called PLEKHA1, which is also associated with a person’s risk of developing AMD. It, too, appears to be involved in the inflammation. Several other gene candidates are being studied to determine what role they might play in the development of this devastating eye disease. But to date there is no clinical way to test for this gene deficit or to know what type of inheritance pattern it has.
The exact cause of this disease is not known, but it is thought that the plaquelike metabolic deposits called drusen, which begin to form under the retina as we age, end up damaging the light-sensing cells, and as these die off, the vision in the center of our visual field begins to fade.
There are actually two types of AMD, the “dry” and the “wet.” The “dry” accounts for 90 percent of the cases and does not usually cause a total loss of reading vision. There is no treatment for “dry” AMD, but those who suffer from it need to be monitored carefully as the condition may deteriorate into “wet” AMD, which does cause blindness and occurs when tiny abnormal blood vessels develop under the retina, causing swelling or breaking and bleeding.
Treatment of “wet” AMD is still a work in progress. Laser therapies have been utilized to burn out these abnormal vessels, but not very successfully. Photodynamic therapy has been more successful in preventing further deterioration of vision. The procedure involves the intravenous injection of a photosensitizing dye, which accumulates in the abnormal new vessels; a red laser then destroys these new vessels.
The treatment is expensive, however, requires access to a red laser, and must be repeated every few months. A new medication introduced recently, known as Macugen, has shown much promise. Basically, when it is injected into the eye, it interferes with the growth of these new blood vessels. The only problem is that the effects of the medication are temporary; it needs to be readministered every six weeks. And while it succeeds in preventing further vision loss, only a few people have reported an actual gain in their visual acuity.
Preventing Macular Degeneration
While macular degeneration is a hot topic of conversation among those in their seventies, we tend to forget that there are some things we can do in our lifetime to prevent it.
1. Protect your eyes from UV rays by wearing sunglasses beginning at an early age.
2. Nutrition also plays a significant role, and this is why I keep bringing up the issue of maintaining a healthful diet throughout your life. Studies show that people with the highest consumption of vegetables rich in carotenoids, like raw spinach, kale, and collard greens, have about half the risk of developing macular degeneration when they get older than those who did not follow such a diet.
3. Smoking is another big risk factor for developing macular degeneration; in fact, smoking may actually double your risk of AMD.
4. One final prevention tip: If you want to avoid macular degeneration, remember to maintain a normal blood pressure.
Certain plant substances may be able to reverse the degeneration of AMD in some people. Two carotenoid plant substances, specifically lutein and zeaxanthin, which are present in the macular pigment melanin, seem to prevent macular degeneration—and may even improve the existing disease—by absorbing blue light and by acting as antioxidants to remove free radicals. Here is the lutein-zeaxanthin content of various fruits and vegetables (micrograms/100 grams):
micrograms/Vegetable/Fruit 100 grams
Collard greens 16,300
Spinach (cooked, drained) 12,600
Spinach (raw) 10,200
Parsley (not dried) 10,200
Mustard greens 9,900
Dill (not dried) 6,700
Scallions (raw) 2,100
Leeks (raw) 1,900
Broccoli (raw) 1,900
Broccoli (cooked) 1,800
micrograms/Vegetable/Fruit 100 grams
Leaf lettuce 1,800
Green peas 1,700
Brussels sprouts 1,300
Summer squash 1,200
Corn (yellow) 790
Yellow pepper (raw) 770
Green beans 740
Green pepper 700
Cucumber pickle 510
Green olives 510
Click here to check out Dr. Manny's book The Check List (Harper Collins, 2007), from which this article was excerpted.
Dr. Manny Alvarez is the managing editor of health news at FOXNews.com, and is a regular medical contributor on the FOX News Channel. He is chairman of the Department of Obstetrics and Gynecology and Reproductive Science at Hackensack University Medical Center in New Jersey. Additionally, Alvarez is Adjunct Professor of Obstetrics and Gynecology at New York University School of Medicine in New York City.