an uncorrected visual acuity of at least 20/40 (6/12) with both eyes open. ; O; s4 W$ u3 V# g) j- q, z
visual aids (glasses or contact lenses) must have vision of 20:20 (6:6) with both eyes open. + n: p) U6 L7 V- h6 v7 Y
* C6 ]1 ~7 F% X% A# m6 e
请问上面的意思是什么?相当于国内什么等级的视力?谢谢!