1Department of Preventive Medicine, Yonsei University College of Medicine, Seoul, Korea
2Department of Public Health, Yonsei University Graduate School, Seoul, Korea
3Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea
4Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
5Cardiovascular and Metabolic Diseases Etiology Research Center, Yonsei University College of Medicine, Seoul, Korea
Copyright © 2017 The Korean Society for Preventive Medicine
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.