Abstract: An eye monitor is disclosed for monitoring the size of a pupil of a monitored subject. The eye monitor includes a tracking device for tracking movement of the user's pupil and a monitoring device for monitoring the size of the user's pupil. The eye monitor provides for a continuous and real time analysis of the subject's eye and in particular the pupil of the eye, to determine whether the subject has been exposed to harmful chemicals and without requiring the subject to actively participate in the monitoring.