an uncorrected visual acuity of at least 20/40 (6/12) with both eyes open. ( X; x# w$ A7 F' w& V
visual aids (glasses or contact lenses) must have vision of 20:20 (6:6) with both eyes open. ( M# x" W% L z/ o! R4 l
5 f" c) d: D4 I9 F
请问上面的意思是什么?相当于国内什么等级的视力?谢谢!