Abby,
We had a chin, Seamus, who was born blind in 2001. His mama was older,10, and the pregnancy was a complete surprise to us.( Previously, all my mama chins had stopped littering around 5 or 6.) Anyway, even from an early age, Seamus was very adept at getting around the cage he was born in,which was like a large avian cage(48" tall) that had a coop box, 3 large cross branches and 2 perching ledges up high. In other words, it's not exactly a straightforward cage arrangement. He never had a problem with it, and had the layout memorized. He at times would bound around like any young chin, and you would never know he was blind. I did have him examined by my vet to confirm his blindness, as I initially thought he might have some peripheral vision(he didn't). So I don't think that it's absolutely neccessary to have a blind chin in one level cage situation. But they'd need to be in whatever cage environment you chose pretty much from a very early age. The only thing I did was make sure his cage set up was exactly the same, always, and if we had a petsitter, I'd do a little diagram for her( ie coop here, toys there,food bowls here, etc).
Anyway, Seamus grew to be a big happy boy, and was very playful. He passed away at age 6, (cause unknown).Other than not eating a few days before he died, he was never sick. We loved having him in our chinnie family, and was sorry to lose him so soon. He was a great guy!