4e is a very tactical game, and there are several powers which cause blindness. However there don't seem to be any rules on how blindness affects movement and a lot of my players don't want to allow a blind creature to still be able to move effectively, know which square to go to, etc. with perfect precision and the only penalty being -5 to attack rolls.

I DO NOT want to burden down my fight with random direction rolls, or making acrobatics checks every square moved, but I'd like to see how others have ruled on this.

I've thought about just making all movement considered as if you were moving in difficult terrain to represent you can't move as well while blind, but you are not immobilized. Other than that I'm not sure how to rule it so that it does not slow down my game sessions.