This guy above has these gel covered 'hairs' that are super sensitive to movement allowing it to 'see' the surroundings via vibrations.
See! The eye sockets are still there, but they don't do anything!!
I just thought these below were interesting. They're the skulls of blind snakes. As an aside, I was lucky enough to see a blind snake in Namibia when I was curious enough to turn over the right rock.
Texas blind salamander
Kauai cave wolf spider