1. Department of Ophthalmology, College of Medicine, Kosin University, Busan, Korea.
2. Department of Preventive Medicine, College of Medicine, Inje University, Busan, Korea.
3. Department of Preventive Medicine, College of Medicine, Kosin University, Busan, Korea.
4. Department of Preventive Medicine, College of Medicine, Dong-A University, Busan, Korea.
5. Division of Mathematical Sciences Statistics, Pukyong National University, Busan, Korea.