You should make the pupils blood red; enlarge the eyes; raise the bottom eyelid on one of the eyes and have a Cheshire Cat smile. Like Insane Twilight! Or something of the sort. :P
Frankly, this could have been thought-out and planned more carefully.
That is, the emphasis on the character's insanity. He only looks shocked in your skin.
Try and capture the emotion and identify the elements that comprise it.
Psychology is Magic, after all. *squee*