title: Determining the accuracy of an eye tracking system for laser refractive surgery.
abstract: OBJECTIVE
  Patient eye and head movements during laser refractive surgery may result in errors between the surgical beam position and the desired location for optimum correction. This, in turn, may lead to reduced postoperative vision, including increased higher order aberrations of the eye. Active eye tracking systems are often incorporated into laser delivery systems, which aim to reduce the effect of patient eye movement.
  
  
  METHODS
  In this study, the accuracy of an eye tracking system designed for laser refractive surgery was determined. An enucleated porcine eye was attached to a scanning device and the movement measured using the eye tracking system. The recorded position is compared to the preprogrammed position of the scanning device.
  
  
  RESULTS
  The system demonstrated an accuracy of 0.06 m for an intact cornea and 0.1 mm for a cornea with a thin flap removed. This compares to an average decentration of ablation of 0.4 mm for patients relying on passive fixation, as measured by previous clinical trials.
  
  
  CONCLUSIONS
  implementation of this eye tracker would lead to improved alignment between the laser and eye during laser refractive surgery.
authors.affiliation: Centre for Ophthalmology and Visual Science, Lion's Eye Institute, The University of Western Australia, Nedlands, Australia. taylorn@cyllene.uwa.edu.au
authors.forename: N M
authors.initials: NM
authors.lastname: Taylor
authors.forename: R H
authors.initials: RH
authors.lastname: Eikelboom
authors.forename: P P
authors.initials: PP
authors.lastname: van Sarloos
authors.forename: P G
authors.initials: PG
authors.lastname: Reid
mesh_terms: D000818:Animals; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation / Q000592:standards*; D005133:Eye Movements; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy; D011680:Pupil; D054140:Refractive Surgical Procedures; D015203:Reproducibility of Results; D013552:Swine; D014741:Video Recording