Patent ID: 6702809
Filing Date: 2004-03-09
Classification: A61B,A61F,B23K

Abstract:
A system for tracking an eye of a living patient during laser eye surgery, the eye having a first feature and a second feature with a contrast border therebetween, the system comprising:an illumination source oriented toward the eye to provide illumination light, the illumination light illuminating a first region of the eye extending across a first portion of the contrast border and including a first portion of the first feature and a first portion of the second feature of the eye, the illumination light also illuminating a second region of the eye extending across a second portion of the contrast border and including a second portion of the first feature and a second portion of the second feature; a laser delivery optical train oriented toward the eye and adapted for receiving the illumination light reflected and scattered from the eye, the optical train focussing the scattered reflected light along an optical path to an image; a photodetector system disposed in the optical path of the scattered reflected light from the optical train, the photodetector system generating a first signal and a second signal, the first signal indicating an integrated illumination of the focussed light from the first region of the eye, the second signal indicating an integrated illumination of the focussed light from the second region of the eye; a processor coupled to the photodetector system to measure a lateral movement of the eye, by comparing the first signal to the second signal, and to produce an error signal from a difference between the first signal and the second signal which is normalized to ambient light using a sum of the first signal and the second signal; and a drive mechanism coupled to the processor to shift the optical train in response to the lateral movement of the eye so as to maintain alignment between the optical train and the eye.