为了解和掌握中小学生视力低下、龋齿、沙眼常见的 3种疾病 (以下简称“三病”) ,为制定有效的防治措施提供依据。现将铜陵县 1995～ 1999年对中小学生的三病患病情况的调查分析如下 :1　对象与方法1995～ 1999年每年 4～ 11月 ,对全县各乡镇中学和中心小学的学生进行健康体检 To understand and grasp the primary and secondary school students with low vision, dental caries, trachoma common three diseases (hereinafter referred to as “three diseases”), to provide an effective basis for prevention and treatment measures. Now Tongling from 1995 to 1999, primary and secondary school students in the three disease prevalence survey were analyzed as follows: 1 objects and methods 1995-1999 From April to November each year, the county township primary schools and primary school students for physical examination