I was talking to a vet about this at a clinic years ago (dog had a CERF every year but around 6-7 years old developed a certain type of cataract). His opinion was that is was a 'breeder option'.
What was marked on the exam form? If it was a punctate cataract did the ACVO mark it significance unknown? If so, then it will pass CERF or OFA as a breeder option. If that's what it was I would still breed her but not to a dog that also has that in it's lines as I wouldn't double up on it.
Depends on the type of cataract. Juvenile cataracts can theoretically show up as late as 6-7 yrs, and in that case, the girl would not pass. MOst punctates are breeder options.
My 6yr old boy was just checked too and same thing. He passed ofa eye cert and now has breeder code : EYES Jun 10 2014 Jul 24 2014 75 NORMAL W/BREEDER OPTIONS NOTED
E1:Cataract - significance unknown