When can a puppy start to see?

My mom just bought a pitbull that is 4 weeks old and she thinks it's blind. I think we just have to wait till its older so it can see. It doesn't react to light or anything. So do you think she's blind?

FOUR weeks???????? Something is wrong here! Blind or not, that pup still needs her mother. Where the devil did you buy her?

It probably is blind. Bad breeding practices. Puppies start seeing at 2 weeks old.

You should have waited until it was older to get it. Puppies should be with mom and litter mates until 8 weeks of age. Even if it's not blind you will have no end of medical and behavioral problems. Shame on the breeder for not keeping that puppy longer and shame on your mother for not doing her homework. The pup needs to see a vet. Period.