Smokers risk vision loss in twilight years

"Smoke Gets in Your Eyes" used to be just an old nightclub lament. Now, with the publication of two reports that strongly link cigarette smoking to vision loss, the phrase seems prophetic.

 The studies show that long-term, heavy smokers have more than twice the normal risk of age-related macular degeneration (AMD), a disorder in which the region of the retina that captures images in the center of the visual field breaks down. The leading cause of vision loss and newly diagnosed blindness in people age 65 and older, AMD afflicts 1.7 million people in the United States.

"It can make it very difficult to perform the activities of daily living -- including driving, reading, and watching TV," says William G. Christen of Harvard Medical School in Boston. Christen is coauthor of a report on AMD and smoking in 21,157 men in the Physicians' Health Study. That article, along with a comparable report on AMD among women in the Nurses' Health Study, appears in the Oct. 9 Journal of the American Medical Association.

 Doctors have yet to determine why AMD occurs. Previous research has implicated low concentrations of zinc, vitamin E, and beta carotene in the blood; these antioxidants sop up harmful molecules called free radicals. Poor blood flow to the retina may also be a cause. Smoking ranks as a risk factor because it reduces concentrations of these antioxidants and impairs circulation, Christen says.

 Once AMD begins, the pinhead-size macula develops yellow spots and lumps called drusen. Drusen apparently accumulate because garbage disposal cells, called phagocytes, fail to clear away cellular debris. In the worst cases, leaky blood vessels worm their way into the retina and flood the macula. The eye's efforts to repair itself lead to scarring, which only makes matters worse.

 Doctors lack an effective means of halting this process. Although laser surgery can seal off wayward blood vessels, it only delays the inevitable, studies have shown. Peripheral vision may survive, but faces blur into featureless ovals. The central words in any sentence disappear.

 In such a situation, prevention becomes a person's best defense--hence the rising interest in the link between AMD and smoking.

 Christen and his coworkers probed for such a link in the huge study of male physicians, age 40 to 84 when the study began in 1982. Relying on medical records and questionnaires with detailed questions on smoking, they identified 268 cases of AMD. The study found that two-pack-a-day smokers had 2.5 times the disease risk of men who had never smoked -- and the longer the men smoked, the higher their risk.

 Johanna M. Seddon, also of Harvard Medical School, and her coauthors focused on the 31,843 women in the Nurses' Health Study, who were 50 to 59 at the outset in 1980. Their results were virtually identical. Women who smoked two packs a day had a 2.4 times greater risk of AMD than women who never smoked. The study also found that much of the excess risk persisted, even in women who had quit smoking 15 years ago. "Women who choose not to smoke can reduce their risk of developing this disease by more than half," Seddon asserts.

 Saying no to cigarettes "may reduce the loss of vision and may ensure a brighter view of the world for years to come," conclude Ronald Klein and Barbara E. K. Klein of the University of Wisconsin Medical School in Madison in an accompanying editorial aptly titled, "Smoke gets in your eyes, too."