an uncorrected visual acuity of at least 20/40 (6/12) with both eyes open. $ v- j: x; N. @' ~visual aids (glasses or contact lenses) must have vision of 20:20 (6:6) with both eyes open. $ @0 G4 |9 q" `1 t9 s1 P) r
/ O1 E0 b) m4 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!