pop-eyed 
adjective
(Of a person) having bulging or staring eyes, typically through surprise or fear: Neil has a glimpse of the driver, pop-eyed, standing on the brakes...
- I'm pretty sure that if I ever actually meet Ben Hammersley he'll be a kind of wild-haired, pop-eyed genius type with a pencil behind each ear and a short attention span.
- He stops, to stare at the screen, open-mouthed and pop-eyed.
- The pugs, one gentle-eyed and adoring, the other pop-eyed with indignation, are reminiscent of the diametrically opposed judgments that have dogged Pullman's work, outlandishly exemplified by the Hitchens siblings.