Thanks everyone!
I had the same problem. You know those little glass beads that go at the botttom of fish tanks, the ones you can get in the baggies for like $3? I used those and just painted the flat backs! Somehow, the shape of the glass distorts the eye underneath and makes it so that the eye "looks" at you no matter which way the sculpture's head is turned! It's actually sorta creepy, but at the same time, really cool, lol.
I took some pictures, because I don't think I explained that very well. Hope this helps!
Sorry for the blurriness, my camera died after that second picture.