Ok, I picked up the eyeless body, the "fog" and monster showed up, played the third tape and saved, then it went back to normal, the door is shut, and the only thing to interact with are the notes and doors, as well as the two blind monsters in that one room.
I'm pretty sure when you get into Dr.Brundles office and pick up the eyeless corpse, the red eye'd monster show up. It gets darker and foggy, and the door with the retina scan should open on it's own. At this point I hadn't played the tape or saved so instead of going to the door I went back, and after I went back into the Lab it was no longer darker. The monsters were gone, the office was already picked open, I have the body, and the door is shut.
Also I doubt it would matter but it was past 12 when I was playing, and when I tried restarting I played midnight mode instead.
To sum it up I have the body, but the door is shut.