an uncorrected visual acuity of at least 20/40 (6/12) with both eyes open. % H9 Z J! n1 A7 x/ e+ ]. _( h2 ovisual aids (glasses or contact lenses) must have vision of 20:20 (6:6) with both eyes open. & J4 z0 q& N5 C% M$ n! x
+ S8 T! d$ U5 c% n) N$ ~+ k
请问上面的意思是什么?相当于国内什么等级的视力?谢谢!