From what I've read, deer see pretty good at night, and it don't surprise me that you'd spook one then. It has something to do with the rods and cones in their eyes. You know how when you see a deer in the dark sometimes and their eyes kinda glow greenish? I think it's sort of like a cat. In general though, deer have mediocre vision, and if they detect you with sight it's usually by spotting motion.

I've also read that deer see the color blue really well, but who knows. lol