Three Blind Mice… Err, Rats

Our new pet rats are great, and Oreo is becoming a real friend.  Bobby Jack, however, seems very nervous all the time.  He squeaks and sneezes a lot, and he uses his nose to try to burrow into my hand when I hold him.  We are thinking he might be blind.  I don’t know that much about rat behavior; these are my first pet rats.  But it just seems like Bobby Jack can’t see.  Are there vision tests for rats?  I guess I have some research to do about rat blindness, squeaking, and sneezing…