How to know if Guinea Pig is blind?

Hey guys, a friend of my mothers had a single guinea pig left in her care and was rehoming it. As of yesterday I have taken on a sweet little lady named Matilda. She is white with pink eyes but has good teeth and good hearing, however I suspect she is blind. What tips do you guys have to tell conclusively whether or not she is? I will be back at work soon and she will get less attention during the day so I want to set her up properly before then. Cheers :)

(FYI Matilda showed up in not so great condition and had been living in a free range set up so I doubt her previous owner knows. I had a LOT of care work to do yesterday...)