1. A system for monitoring movement of a person's eye, comprising: a device configured to be worn on a person's head; a light source for directing light towards an eye of the person when the device is worn; a camera on the device for monitoring movement of the eye, the camera configured for generating video signals representing video images acquired by the camera of the eye; a processor communicating with the camera for processing the video signals to identify a pupil of the eye from the video signals and to monitor at least one of a size of the pupil and an eccentricity of the pupil; and a display coupled to the processor for displaying video images of the eye from the video signals processed by the processor, the display superimposing a graphic onto the video images to identify the pupil.