1. From the Department of Health Promotion Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea;
2. Catholic Institutes of Visual Science, The Catholic University of Korea, Seoul, Korea; and the
3. Catholic Institutes of Visual Science, The Catholic University of Korea, Seoul, Korea; and the3Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.