One of the most common causes of vision loss in adults may be waning. Age-related macular degeneration was estimated to affect 1.75 million Americans in 2004, and that number was expected to rise to 3 million by 2020. But a federally funded study by Dr. Ronald Klein of the University of Wisconsin School of Medicine and Public Health suggests that the disease is actually on the decline.
Klein and his colleagues took photos of the eyes of more than 7,000 people from various locations and ethnic backgrounds who were part of the 2005-2008 National Health and Nutrition Examination Survey. The photos were analyzed for any sign of macular degeneration, a disease that affects tissue at the back of the eye. A similar study conducted in the 1988-1994 national health survey found macular degeneration in 9.4 percent of adults over 40. Klein’s study found the disease in only 6.5 percent, despite more sensitive detection methods. Since macular degeneration has been linked to smoking and diet, healthier lifestyles may account for some of the decrease.
BOTTOM LINE: The most common cause of vision loss in people over 40 may be on the decline.
CAUTIONS: The data from the two surveys were analyzed somewhat differently, which may explain some of the observed decline.
WHERE TO FIND IT: Archives of Ophthalmology, January 2011.
More teen girls lose hearingTeenage girls have caught up with teenage boys when it comes to noise-induced hearing loss, according to a Harvard study. In a national survey during 2005 and 2006, 35 percent of teenage girls reported exposure to loud noises over the past 24 hours, including concerts, clubs, and listening to headphones. In a similar survey conducted between 1988 and 1994, only 20 percent of girls reported such noise exposure. The new survey found that girls were also less likely to use earplugs than boys. Perhaps as a result, the researchers said, the number of teenage girls with temporary hearing loss, an effect that may be cumulative, increased from 12 percent in the earlier survey to 17 percent in 2005-06.
The dangers of listening to music through headphones is a topic of debate among researchers, but most agree on the damage caused by loud concerts and clubs. Elisabeth Henderson, a Harvard Medical School student who was the lead researcher of the federally funded study, said she hopes the results will encourage doctors to promote use of earplugs. Both surveys tested more than 2,000 teenagers ages 12-19.
BOTTOM LINE: Teenage girls are suffering temporary hearing loss at a higher rate, possibly because of increased exposure to loud music.
CAUTIONS: There have been no studies done in the United States to track the damage done by loud noises over time.
WHERE TO FIND IT: Pediatrics, January 2011.