title: Eye movement during laser in situ keratomileusis.
abstract: OBJECTIVE
  To measure eye motion in patients having laser in situ keratomileusis (LASIK) using a video technique and determine centration and variance of the eye position during surgery.
  
  
  METHODS
  Laser refractive surgery center.
  
  
  METHODS
  The procedure was videotaped in 5 consecutive eyes having LASIK performed by a single surgeon with the VISX Star S2 excimer laser. Following surgery, video images of the eyes were digitized and stored in a computer for processing. Digitized images were obtained at a rate of 25 images per second during the laser procedure. The pupil margin and a visual landmark, such as a scleral blood vessel, were identified in the initial image of each eye. Custom software was used to track the location of the landmark and the pupil center in subsequent images.
  
  
  RESULTS
  Three of the 5 eyes were well centered on average. The remaining 2 eyes were decentered inferiorly by approximately 0.25 mm. The standard deviation in all eyes was approximately 0.10 mm.
  
  
  CONCLUSIONS
  With these techniques, the position of the entrance pupil center relative to the excimer laser axis could be determined. Although the system is not fast enough to be used during surgery, it does allow quantification of centration and intraoperative motion after surgery.
authors.affiliation: Department of Ophthalmology, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: J
authors.initials: J
authors.lastname: Schwiegerling
authors.forename: R W
authors.initials: RW
authors.lastname: Snyder
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D012030:Refractive Errors / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D016896:Treatment Outcome; D014741:Video Recording; D014792:Visual Acuity