the effect of metal deposition on antioxidant enzymes of lens in smokers of karachi, pakistan

background: blindness due to cataract is a major and important problem in pakistan. the problem is expected to increase in future due to increase in tobacco smoking. the aim of study was to look for the mechanism associated with metal deposition and its effect on antioxidant enzymes in lens of smokers in karachi, pakistan. methods: 20 cataract patients were randomly selected from out patient department (opd) of layton rahmatulla benevolent trust hospital lrbt hospital, karachi in accordance to inclusion and exclusion criteria. 10 were chronic smokers and 10 were non-smokers. after extra capsular cataract extraction, lenses were cut into two equal halves. in one half, concentration of lead, cadmium and copper were determined by atomic absorption spectrophotometry; in the other half, glutathione peroxidase and superoxide dismutase were estimated by kit method using plate reader. results: the activity of superoxide dismutase and glutathione peroxidase were significantly decreased in lenses of cigarette smokers as compared to non-smokers. concentration of copper, lead and cadmium were significantly higher in lenses of smokers than those of non-smokers. a highly negative correlation of both enzyme concentrations was found with concentration of copper, lead and cadmium. conclusion: decreased level of anti-oxidant enzymes, superoxide dismutase and glutathione peroxidase with increased level of metals in smoker’s lenses suggest that metals produce an oxidative stress affecting the enzyme level and its activity. these changes lead to lenticular protein changes leading to cataract.