A medical staff member introduces eye's structure and cause of myopia in Donglin primary school in Donglin Township of Huzhou City, east China's Zhejiang Province, Sept. 4, 2018. Classes are being taken to popularize the knowledge of protecting eyes as China aims at curbing the rise in nearsightedness-or myopia-among children and teenagers. (Xinhua/Xu Yu)

Medical staff members introduce ways of protecting eyes at a class in Donglin primary school in Donglin Township of Huzhou City, east China's Zhejiang Province, Sept. 4, 2018. Classes are being taken to popularize the knowledge of protecting eyes as China aims at curbing the rise in nearsightedness-or myopia-among children and teenagers. (Xinhua/Xu Yu)

A medical staff member introduces eye's structure and cause of myopia in Donglin primary school in Donglin Township of Huzhou City, east China's Zhejiang Province, Sept. 4, 2018. Classes are being taken to popularize the knowledge of protecting eyes as China aims at curbing the rise in nearsightedness-or myopia-among children and teenagers. (Xinhua/Xu Yu)

A student checks the eyesight in Donglin primary school in Donglin Township of Huzhou City, east China's Zhejiang Province, Sept. 4, 2018. Classes are being taken to popularize the knowledge of protecting eyes as China aims at curbing the rise in nearsightedness-or myopia-among children and teenagers. (Xinhua/Xu Yu)

A teacher teaches a student to do eye exercises in Donglin primary school in Donglin Township of Huzhou City, east China's Zhejiang Province, Sept. 4, 2018. Classes are being taken to popularize the knowledge of protecting eyes as China aims at curbing the rise in nearsightedness-or myopia-among children and teenagers. (Xinhua/Xu Yu)