Refractive errors in 3-6 year-old Chinese children: a very low prevalence of myopia?

Supported by the National Natural Science Foundation of China, Beijing, China (grant no.: 81200714;http://www.nsfc.gov.cn/); Foundation for Distinguished Young Talents in Higher Education of Guangdong, Guangdong Province, China (grant no.: LYM 11009;http://www.gdhed.edu.cn/) and the Science and Information Technology Bureau of Guangzhou, Guangdong Province, China (grant no.: 2011Y2-00018-3;http://www.gzsi.gov.cn/).