It may be possible that the deer's eyes have small pupils after being shot with a spotlight. At night, a deer's pupil's enlarge to gather more light. If a deer is shined with a spotlight, their eyes try to focus and their pupils must get smaller to be able to see without being blinded so badly. It's like nightvision goggles, too much light and you can't see. Since the deer have nightvision already installed they just need to tune it down when they get shined.....Maybe? I dunno..Just a thought..I have a hard time explaining my thoughts [&:] lol