Where are the Khaasta?
If the base creature is CR 3 or thereabout, pre-blindness, I assume some amount of racial HD, depending on associated classes, it is entirely possible that this fellow has several more levels of druid than a human CR 5 druid, possibly enough to gain wildshape. (He's a druid, he's gonna have Natural Spell)
That means:
The real question is, if he can wildshape, is he still blind?
Anyways, more on topic, I concur with Mistwell and Moon-Lancer on -2 CR.
Max out Listen, as Listen Checks can give a general direction.
I recommend an enclosed area, large AoE spells, and summonings.
If he has an animal companion with him, and he probably does, it's possible that the companion can tell him what direction and roughly how far different enemies are. This means, though, that if the companion dies, he's probably very shafted and displeased.