In perspective: Eye tracking and autonomous laser radar

The results of Pallikaris and colleagues with a small scanning spot laser a nd laser radar eye tracking deserve comment to put this new technology in p erspective. It is likely that eye tracking will become an increasingly impo rtant part of excimer laser refractive surgery, and I trust my comments her e will clarify that new addition to our knowledge of technology and surgica l techniques (Pallikaris IG et al. Photorefractive Keratectomy With a Small Spot Laser and Tracker, J Refract Surg 1999;15:137-144). Eye tracking, as introduced in laser refractive surgery, can be defined and differentiated by its functional and detection features. Functionally, eye tracking can be active or passive or both. Active eye tracking means the l aser detects a change in location and moves the next laser pulse to attempt to meet that change. Passive tracking, however, simply detects change and shuts down further laser pulsing when the change exceeds a predetermined di stance. Detection features differentiate the frequency of sampling and spee d in which the tracker responds. Infrared camera videotracking is the simpl est form of eye tracking and is limited in its detection frequency by the v ideo camera frame capacity. Laser radar eye tracking is more sophisticated and involves a laser transmitted signal which is associated with a much hig her detection frequency because of the very high frequency pulsing capacity of lasers. With this background, let me explore some of the details of the LADARVision tracking system which characterizes the Autonomous excimer las er.