When a coroner or a doctor checks for vital signs, one of the easiest ways to determine if someone is alive is by shining a light directly into their eyes. If the pupils do not constrict - something even the best-trained yogis can't control - then the person is dead.
Petechiae on the face and eyes are a sign of a death by asphyxiation. They are thought to result from an increase of pressure in the veins of the head and damage to blood vessels.
Discolouration in the eyes can indicate some sort of toxin, as do the classic white rings on fingernails (arsenic). Breath that smells of almonds also indicate poison.
I'm eating almonds now. Am I poisoned?