AIM: To determine the effect of metabolic syndrome on age-related cataract formation.METHODS: We analyzed data for 2852 subjects [41.8% men and 58.2% women; mean (±SD) age, 52.9±13.9y], taken from the Korea National Health and Nutrition Examination Survey 2008. Metabolic syndrome was diagnosed by criteria proposed by the Joint Interim Societies. Cataract was diagnosed by using the Lens Opacities Classification System III. The association between metabolic syndrome and cataract was determined using age-adjusted and multivariable logistic regression analyses. RESULTS:In multivariable analyses, men with metabolic syndrome had a 64% increased risk of nuclear cataract [odds ratio (OR), 1.64; 95% confidence interval (CI), 1.12-2.39]. Women with metabolic syndrome had a 56% increased risk of cortical cataract (OR, 1.56; 95% CI, 1.06-2.30). Men and women with metabolic syndrome had a 46% (OR, 1.46; 95% CI, 1.01-2.12) and 49% (OR, 1.49; 95% CI, 1.07-2.08) increased risk of any cataract, respectively. The prevalence of nuclear and any cataract significantly increased with an increasing number of disturbed metabolic components in men, and prevalence of all types of cataracts increased in women. Men using hypoglycemic medication had an increased risk of nuclear (OR, 2.62; 95% CI, 1.41-4.86) and any (OR, 2.27; 95% CI, 1.14-4.51) cataract, and women using antidyslipidemia medication had an increased risk of cortical (OR, 2.18; 95% CI, 1.12-4.24) and any (OR, 2.21; 95% CI, 1.14-4.26) cataract.CONCLUSION: Metabolic syndrome and its components, such as abdominal obesity, high blood pressure, and impaired fasting glucose, are associated with age-related cataract formation in the Korean population.