1. Department of Ophthalmology, Shanxi Eye Hospital, Taiyuan, Shanxi, P.R. China
2. Department of Ophthalmology, The Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, P.R. China
3. College of electrical and information engineering, Hunan University, Changsha, Hunan, P.R. China
4. Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, Hunan, P.R. China
5. Department of Ophthalmology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
6. Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, USA