I just thought I'd let people know that A) I worked out how to change state flags, thus solving the blindness problem, and B) I think I know what caused it.
My primary character is Chaotic Evil (second time through, add some spice
and I realised that he's blinded whenever Aerie casts Holy Smite. Holy Smite is meant to blind evil creatures for one round, but it seems to be permanent when cast on the character. So, no more smiting for her!
Thanks for all the help!