Researchers have found that smokers are more likely to have an increased long-term risk and greater progression of the eye disease age-related macular degeneration (AMD).
Macular degeneration is a medical condition predominantly found in elderly adults in which the center of the inner lining of the eye, known as the macula area of the retina, suffers thinning, atrophy, and in some cases, bleeding.
The study, which submitted a report in the January issue of Archives of Ophthalmology, identified smoking as one of the changeable risk factors for age-related macular degeneration (AMD), which has turned out to be a leading cause of vision loss in older Americans, according to information in the article.
There are many ways through which smoking contributes to AMD, and it reduces antioxidant levels, decreases the blood flow around the eye and affects the pigments (coloration) in the retina.
The researchers, Ronald Klein, M.D., M.P.H., and colleagues at the University of Wisconsin School of Medicine and Public Health, Madison, studied 4,926 residents of Beaver Dam, Wis., in the age groups of 43 to 84 years in 1987 to 1988.
The participants were initially examined in 1988 to 1990 and they were then re-examined after every five years for the next 15 years. In order to find out about the presence and status of AMD, photographs of the retina were taken and measured.
The study found at the start that 21 percent of the men and 18 percent of the women were smokers, and that the smokers had a 47 percent increase in developing early AMD, which is the least severe form of the disease.
It also found that AMD developed at a younger age (69.2 years) than former smokers (72.3 years) and those who had never smoked (74.4 years). Smoking at the beginning of the study was also associated with the cumulative progression of AMD over the 15 years of the study.
"There were few associations of specific characteristics of smoking (e.g., intensity, pack-years smoked, duration and age at initiation and quitting) with AMD outcomes," the authors write.
"In summary, while controlling for other factors, smoking appears to be related to the incidence and progression of AMD in our population," they said.
"This has important health care implications, because early AMD is associated with an increase in the risk of developing late AMD and smoking behaviour is modifiable," they concluded