乘务员的中心视力(简称视力)功能状态,对于铁路机车安全运行是非常重要的。良好的视力不仅能及时准确的判断线路上的信号和各种障碍物, 而且其状态的优劣也是判断乘务员其它视觉功能的基础。然而,影响乘务员视力状态的因素很多,不仅有乘务员自身的年龄因素,而且还存在着一些特 Cabin’s central vision (referred to as vision) functional status, for the safe operation of the railway locomotive is very important. Good vision can not only timely and accurately determine the signal line and a variety of obstacles, and the merits of its status is to determine the basis of other visual functions steward. However, there are many factors that affect the crew’s vision status, not only the crew’s own age factors, but also some special