9. SMOKING & CATARACT

SMOKING - INCREASES OXIDATIVE STRESS ON LENS PROTEIN
 http://www.agingeye.net/cataract/cataractinformation.php
The observational evidence linking cigarette smoking with risk of cataract is well-established; heavy smokers (15 cigarettes/day or more) have up to three times the risk of cataract as nonsmokers. Smoking is thought to increase risk of cataract, at least in part, by increasing oxidative stress in the lens. Oxidative stress can be caused by free radicals produced by reactions in the presence of tobacco smoke or other air pollutants; these free radicals may directly damage lens proteins and the fiber cell membrane in the lens. Intake of certain antioxidants has been shown to decrease cataract in a number of studies. A recent study investigated the effect of smoking cessation on cataract in US men and women (Am J Epidemiol 2002;155:72-9). Findings suggested that any healing from damage due to cigarette smoking occurs at a very modest pace, and this emphasizes the importance of never starting to smoke or quitting early in life. Compared with current smokers, former smokers who had quit smoking 25 or more years previously had a 20% lower risk of cataract extraction. However, risk among past smokers did not decrease to the level seen among never smokers.