April 2010

 

OPHTHALMOLOGY NEWS

 

Sight saver & lower risk


by Maxine Lipner Senior EyeWorld Contributing Editor  

   

Quitting smoking may help older patients stave off AMD

Patients over age 80 who have been on the fence about quitting smoking may have a little more incentive to do so, according to Anne L. Coleman, M.D., Ph.D., Fran and Ray Stark Professor of Ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles. Outcomes from her recent study, published in the January 2010 issue of the American Journal of Ophthalmology, show that even after age 80, smoking continues to increase one’s risk for age-related macular degeneration (AMD).

An 80-year-old contingent

The study included 1,958 women who were part of a cohort that initially investigated osteoporotic fractures; they were a mean of 78 years old at the start. “In this cohort of older women we saw that there was a high prevalence of AMD,” Dr. Coleman said. Because this was an older population, the National Eye Institute (NEI), Bethesda, Md., was intrigued. “Many studies end when people are 75 years old, and we don’t have a large number including 80-year-olds,” Dr. Coleman said. “The National Eye Institute provided funds for us to look at the incidence of AMD in these older women.”

The women had initially been recruited for the osteoporotic study when they were about 65. They participated in the study from four sites across the country—Portland, Ore., the Pittsburgh region, the Baltimore area, and Minneapolis. The visual examination that was done initially as part of the broader osteoporotic study was mainly a photographic one. “They had refraction with an automated refractor, lens photographs, and slitlamp photographs done, and they had fundus photographs, too,” Dr. Coleman said. “The slitlamp and lens fundus photographs were read by graders.” When the NEI got involved, they asked the women to return 5 years later. At this point new fundus photos were taken and visual acuity measurements repeated. Then once again the patients’ retinas were graded. Retina specialist Edgar Thomas was the adjudicator for whether or not the macular degeneration had progressed.

Investigators found that in the oldest of the old, incidence of AMD eventually declined. “The incidence of AMD increased with age up to a certain point and then it leveled off,” Dr. Coleman said. “We wondered if that was because a lot of people were dying because this is a survivor’s cohort.” However, this effect was seen even when the risk of AMD numbers thinning due to attrition was controlled for in the cohort.

A synergistic effect

Investigators found that in women ages 74-75, the incidence rate is at about 22%, in those 80-84, this climbs to about 33%, and in those over age 85 it drops back down to around 29%. “It could be that there is a threshold effect with certain diseases,” Dr. Coleman said. “People reach a certain age and if they don’t have it, they’re not going to get it.”

Smoking was also found to significantly increase a woman’s risk of early AMD. “Women who were 80 and older who smoked had an approximately five times greater risk of having AMD than women younger than age 80 who didn’t smoke,” Dr. Coleman said. While age and smoking were both pegged as risk factors for AMD development, there appeared to be a sort of synergistic effect. “We found that this risk was more than additive,” she said. “It wasn’t as if smoking plus age equals risk—smoking made the risk worse.”

Dr. Coleman sees the smoking component as potentially playing an important preventative role. “There’s nothing that people can do about their age, but they can cut back on the synergistic increased risk if they give up smoking,” she said. “That was the more exciting finding because people can do something about this. They can quit smoking even in their 80s and looking at our data, that should decrease their risk of AMD.”

Investigators were not surprised that smoking appears to have an impact. “Smoking is one of the greatest toxins,” Dr. Coleman said. “It decreases serum antioxidant levels, it possibly alters choroidal blood flow, and it has been reported to decrease retinal lutein pigments.”

Overall, Dr. Coleman sees the message as an important one. “The clinical take-home message is that it’s never too late to quit smoking to help protect the eyes from developing age-related macular degeneration,” she said.

Editors’ note: Dr. Coleman has no financial interests related to her comments.

Contact information

Coleman: coleman@jsei.ucla.edu

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