Having a maximal visual acuity of the better eye, after correction by refractive lenses, of one - tenth normal vision or less(20 / 200or less on the Snellen test.是什么意思_Having a maximal visual acuity of the better eye, after correction by refractive lenses, of one - tenth normal vision or less(20 / 200or less on the Snellen test.在线翻译_英语_读音_用法_例句