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