Patent ID: 7708405

Claim:
A pupilometer comprising: an optical sensor including an image capture device having an image detection surface; a sensing optical path coupling the sensor with an eye measurement location, wherein the sensing optical path images at least a sufficient portion of the pupil and the outer iris boundary of an eye disposed at the eye measurement location onto the image detection surface of the image capture device so that the pupilometer can determine a center of the pupil relative to a center of the outer iris boundary; a variable distance viewing target system having a near viewing configuration and a far viewing configuration; and, a processor coupled to the optical sensor and the variable distance viewing target system, the processor having tangible media embodying machine-readable code for determining a relationship between: changes in viewing distance between the eye measurement location and the variable distance viewing target system, including a change between the near viewing configuration and the far viewing configuration, and pupil center drift of the pupil relative to the outer iris boundary of the eye disposed at the eye measurement location, the pupil center drift being separate from any overall movement of the eye, the pupil center drift comprising a change between a first location of the pupil relative to the outer iris boundary when the variable viewing distance target system is in the near viewing configuration, and a second location of the pupil relative to the outer iris boundary when the variable viewing distance target is in the far viewing configuration.