I've only noticed red eye rats sway back and forth, black eye rats can see quite well.
You are correct that a blind rat can get along just fine, I've seen several that were amazingly well adjusted as pets and it didn't slow them down very much either.
http://ratguide.com/health/eyes/glaucoma.php
"There are two classified forms of glaucoma, primary and secondary. In the primary form, pressure in the eye increases without previous disease, and may be a result of genetic predisposition. It tends to affect both eyes but may not occur at the same time".
I myself wouldn't breed a rat that has glaucoma if I was breeding to prove out a trait(such as it being a dwarf) but if making feeders is all that's required let em breed :P






