Department of Ophthalmology and Visual Science, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea. Department of Ophthalmology and Visual Science, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 03312, Korea. Department of Ophthalmology, Dankook University Hospital, Dankook University College of Medicine, Cheonan 31116, Korea. Department of Ophthalmology and Visual Science, Yeoido St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 07345, Korea. Department of Ophthalmology and Visual Science, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Bucheon 14647, Korea. Department of Ophthalmology and Visual Science, St. Vincent's Hospital, College of Medicine, The Catholic University of Korea, Suwon 16247, Korea. Department of Ophthalmology and Visual Science, Incheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Incheon 21431, Korea. Department of Ophthalmology and Visual Science, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Daejeon 34943, Korea. Department of Preventive Medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.