Board Thread:Lore Discussion/@comment-2165692-20140425203121/@comment-24902649-20141223225509

Upon hunting around in CK, I discovered that their sneak-detection system is based solely on sound. So if you are making noise (i.e. holding a spell, or moving objects around), or holding something that's making noise (i.e. a torch), they'll hear it within a certain radius, which is calculated based on how loud the sound is. They also appear to have a much higher sensitivity to sound, while actual light has no effect.

Of course, once they detect you they act like normal enemies and use standard combat AI, but until then, they are quite literally blind. This makes it seem that Bethesda's intention for them was to be blind.

And of course there is all the in-game literature and dialogue. There is no credible evidence that they are not blind.