title: Three-Dimensional Eye Tracking in a Surgical Scenario.
abstract: BACKGROUND
  Eye tracking has been widely used in studying the eye behavior of surgeons in the past decade. Most eye-tracking data are reported in a 2-dimensional (2D) fashion, and data for describing surgeons' behaviors on stereoperception are often missed. With the introduction of stereoscopes in laparoscopic procedures, there is an increasing need for studying the depth perception of surgeons under 3D image-guided surgery.
  
  
  METHODS
  We developed a new algorithm for the computation of convergence points in stereovision by measuring surgeons' interpupillary distance, the distance to the view target, and the difference between gaze locations of the 2 eyes. To test the feasibility of our new algorithm, we recruited 10 individuals to watch stereograms using binocular disparity and asked them to develop stereoperception using a cross-eyed viewing technique. Participants' eye motions were recorded by the Tobii eye tracker while they performed the trials. Convergence points between normal and stereo-viewing conditions were computed using the developed algorithm.
  
  
  RESULTS
  All 10 participants were able to develop stereovision after a short period of training. During stereovision, participants' eye convergence points were 14 ± 1 cm in front of their eyes, which was significantly closer than the convergence points under the normal viewing condition (77 ± 20 cm).
  
  
  CONCLUSIONS
  By applying our method of calculating convergence points using eye tracking, we were able to elicit the eye movement patterns of human operators between the normal and stereovision conditions. Knowledge from this study can be applied to the design of surgical visual systems, with the goal of improving surgical performance and patient safety.
authors.affiliation: University of Alberta,Edmonton, AB, Canada.
authors.forename: Rositsa
authors.initials: R
authors.lastname: Bogdanova
authors.affiliation: University of Alberta,Edmonton, AB, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Boulanger
authors.affiliation: University of Alberta,Edmonton, AB, Canada bin.zheng@ualberta.ca.
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000465:Algorithms; D006804:Ergonomics / Q000379:methods* / Q000592:standards*; D005133:Eye Movements / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D025321:Surgery, Computer-Assisted / Q000193:education / Q000379:methods* / Q000592:standards*
keywords: ergonomics and/or human factors study; image-guided surgery; simulation; surgical education