I had the same bug. I grouped up with someone else and went to the hospital in Cherno, but we ran out of ammo and I got swarmed by zombies. I was losing blood quickly, until I eventually reached -800 or so. There wasn't anything wrong with my character's vision, only broken bones from the zombies. Later, someone shot me a few times with the Makarov, bringing my blood down to around -34000, but I was still completely fine (still had to take morphine though) http://i.imgur.com/bS0p8.jpg