Podcast with Dr. Emily Chew on AREDS
Chew: I'm Emily Chew. I'm the deputy director at the Division of Epidemiology and Clinical Applications at the National Eye Institute at NIH.
Balintfy: Can you tell me some things about what we know about vision loss in older Americans? Is that something that's pretty common?
Chew: That's very common. In fact, the greatest surgical procedure done is for cataracts, so cataract surgery is very important. So cataract is a very major cause of vision impairment in the older Americans along with other disease such as glaucoma, and the leading cause of blindness is age-related macular degeneration.
Balintfy: How many people are affected by age-related macular degeneration?
Chew: Well there are probably at least 2 million people who have, at least in one eye, advanced disease so they experience vision loss, another 8 million who are at risk, and this is according to numbers back in 2004, and they're growing by the minute. So by 2020, we expect that to be more than 50 percent increase at least so that's a huge number of people we're dealing with.
Balintfy: I understand there are different kinds of age-related macular degeneration? Can you explain those?
Chew: So there's what we call the wet and dry. Wet means there are new blood vessels growing and they cause very acute sudden loss of vision and can be preceded by looking into the horizon and seeing distortion. Dry is a very, very slow decrease in the vision and a slow wear and tear on the eye.
Balintfy: Is one more common than the other?
Chew: Well the dry is more common, but the wet is the one that causes the most acute vision loss. That accounts for 80 percent of the vision loss, but the good thing is we have treatment for that.
Since 2006, the FDA has approved other drug that we inject in the eye, and it helps to calm some of the symptoms from the new blood vessels. It doesn't completely get rid of it, but it certainly has revolutionized our treatment for macular degeneration. So in the past people just slowly lost vision, and we slowed down that process. But now we can actually improve people's vision. Forty percent can actually improve their vision, and 90 percent actually stabilize, so that's a remarkable, remarkable finding.
Balintfy: I also understand there is a recent study that shows a lot of people are using dietary supplements in the hopes of helping their vision and maybe combat some of the age-related vision loss. What are we learning about that?
Chew: Well, since 2000 and, really, 2001, we've had a formulation that's made of vitamin C, vitamin E, beta-carotene, zinc, and copper. That reduced the risk of modestly about 25 percent of people going into the more advanced disease, so that's a pretty big treatment effect for a very big public health problem. We looked to see whether we could improve the situation on top of that formulation by adding either omega-3 fatty acids, which are from fish oils, or the lutein zeaxanthin, which are plant carotenoids also called xanthophylls. They're found in the macula, the center part of the eye. They're very important, so what we need to do is to see whether any one of those two would improve it. When we looked together we found that the lutein zeaxanthin actually improved on top of the AREDS formulation.
One further thing was that the beta-carotene, which is in the original formulation, was found to increase the risk of lung cancer in smokers. But in our study we found that even in the former smokers there was a risk. There is almost a double the risk of this creation of lung cancer, which really is disturbing. So we believe that we can improve on that formulation to make it better and safer by excluding beta-carotene and adding a lutein zeaxanthin.
Balintfy: So is there kind of a key take-home message about preventing age-related macular degeneration or basically maintaining healthy vision into old age?
Chew: I think it's very important to have an eye exam, a dilated eye exam, with an eye care provider who can put drops in, make the pupils large, look in, and look for things that you don't know about. For example, glaucoma steals your vision slowly. You can be checked for that. Macular degeneration. If you're at the stage what we call at-risk stage, you could benefit from these vitamins, anything less than that you really can't, so you really need to see your eye doctor.
Balintfy: Can you tell me a little bit more about that age-related eye disease study?
Chew: So the age-related eye study started in 1992. We were interested in looking at the natural history. We also looked at antioxidant vitamins, vitamin C, E, beta-carotene, and also zinc and copper. We found that there was a treatment effect that was wonderful for us. We followed those patients for another five years without that clinical trial, but just their natural history. Still after 10 years, there was still a treatment effect, almost 27 percent reduction, so that's really remarkable. Very few vitamins have been found to have any effect on our general health.
So after that we added these two particular supplements, the omega-3s and also the lutein zeaxanthin to see whether we can improve upon that. Again, we found that there was an improvement with lutein zeaxanthin, which is found in green leafy vegetables such as collard greens, kale, and spinach. So those are good things for you to eat. But even though we found omega-3 didn't work in the study, it's important to remember that in our diet, that's what really triggered it. People with nice, good diets with really lots of fish and lots of green leafy vegetables, they had a lower risk of having macular degeneration.
I think the other risk factor we have to worry about is smoking, it really increases the risk of macular degeneration.
Balintfy: That kind of wrapped up the questions I had. Is there something you'd like to reemphasize?
Chew: It's just important to be sure to get your eye exam. It's very important to maintain your good health.
Balintfy: All right. Great. Thank you so much.
Chew: Thank you.
[0:06:48] End of Audio
Last Updated: January 2014