an uncorrected visual acuity of at least 20/40 (6/12) with both eyes open. ; l+ n# o% M) w
visual aids (glasses or contact lenses) must have vision of 20:20 (6:6) with both eyes open. + w) L0 v6 I4 Z8 T' T/ K
/ x+ V S$ [6 w5 ]# Z- W" |( d$ N
请问上面的意思是什么?相当于国内什么等级的视力?谢谢!