Five heavy metallic elements and age-related macular degeneration: Korean National Health and Nutrition Examination Survey, 2008-2011

Objective: To investigate the association between age-related macular degeneration (AMD) and 5 heavy metallic elements (lead, mercury, cadmium, manganese, and zinc). Design: A cross-sectional study using a complex, stratified, multistage, probability cluster survey. Participants: Participants of the Korean National Health and Nutrition Examination Survey from 2008 to 2011. Methods: Using a standardized protocol, AMD was determined by fundus photograph grading. Blood concentrations of lead, mercury, cadmium, manganese, and zinc were measured. Associations between AMD and these 5 elements were estimated using logistic regression analyses (LRAs). The distributions of the 5 metallic elements in blood were analyzed, and the same set of LRAs estimating the association between AMD and logarithmic-transformed blood concentrations of the 5 elements were also conducted. Main Outcome Measures: Association between AMD and 5 heavy metals. Results: Lead was positively associated with both early AMD and late AMD in all LRAs. Mercury and cadmium also had a positive association with late AMD in all LRAs, but not with early AMD. In contrast, manganese and zinc had an inverse association with late AMD in all LRAs. Manganese and zinc were not associated with early AMD. Using logarithmic-transformed blood concentrations for each metallic element, the LRAs showed similar results compared with those of the LRAs using nontransformed blood concentrations, despite the skewed distribution of these metallic elements in the blood. Conclusions: This study suggests that the toxic heavy metals (lead, mercury, and cadmium) may negatively influence late AMD, whereas essential heavy metals (manganese and zinc) may favorably influence late AMD. Lead may widely affect the pathogenesis of both early and late AMD.