Author Contributions: All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Nash and Cruickshanks. Acquisition of data: Nash, Cruickshanks, B. E. K. Klein, and Tweed. Analysis and interpretation of data: Nash, Cruickshanks, R. Klein, Nieto, Huang, and Pankow. Drafting of the manuscript: Nash. Critical revision of the manuscript for important intellectual content: Nash, Cruickshanks, R. Klein, B. E. K. Klein, Nieto, Huang, Pankow, and Tweed. Statistical analysis: Nash, Cruickshanks, and Huang. Obtained funding: Cruickshanks and Nieto. Administrative, technical, and material support: B. E. K. Klein and Tweed. Study supervision: Cruickshanks.