title: Tracker-assisted photorefractive keratectomy for myopia of -1 to -6 diopters.
abstract: BACKGROUND
  The Autonomous Technologies T-PRK (Tracker-assisted Photorefractive Keratectomy) excimer laser system uses a small beam scanner that allows flexibility in the ablation pattern that is applied to the cornea and incorporates a sophisticated LADARVision eye tracker that is capable of following saccadic movements. This paper describes the first clinical results on sighted eyes for the correction of low myopia.
  
  
  METHODS
  Forty-two normal sighted eyes of 42 patients were treated for spherical myopia between -1.00 diopters (D) and -6.00 D with 6 mm ablations. Visual acuity, refractive error, contrast sensitivity (with and without glare), corneal haze, endothelial cell density, and patient satisfaction were measured.
  
  
  RESULTS
  Mean manifest refraction was -0.39 D +/- 0.68 D at 1 month with regression to -0.94 D at 3 months and -1.05 D at 6 months. At 6 months, 5 (20%) eyes were +/- 0.50 D and 14 (56%) eyes were +/- 1.00 D. Consistent with this undercorrection and regression, uncorrected visual acuity (UCVA) of 20/20 and 20/40 or better was achieved by 10 (40%) and 34 (85%) eyes at 3 months and 16 (40%) and 17 (68%) eyes at 6 months. None of the eyes lost 2 or more lines of spectacle corrected visual acuity. Corneal haze was graded as 1/2 trace or less in 89% to 100% of eyes at all intervals. There was no loss of endothelial cells (mean +/- SD cell density centrally: preop 3115 +/- 322 and 6 months 3220 +/- 333) and contrast sensitivity recovered to baseline levels at 3 months.
  
  
  CONCLUSIONS
  The Autonomous Technologies T-PRK excimer laser system is safe and effective for the reduction or correction of myopia from -1.00 D or -6.00 D. The refractive results may be improved by adjusting the calibration to reduce the undercorrection and by instituting use of topical corticosteroids on an individual basis for those who regress.
authors.affiliation: University of Crete, Department of Ophthalmology, Heraklion, Greece.
authors.forename: I
authors.initials: I
authors.lastname: Pallikaris
authors.forename: M B
authors.initials: MB
authors.lastname: McDonald
authors.forename: D
authors.initials: D
authors.lastname: Siganos
authors.forename: G
authors.initials: G
authors.lastname: Klonos
authors.forename: S
authors.initials: S
authors.lastname: Detorakis
authors.forename: R
authors.initials: R
authors.lastname: Frey
authors.forename: R
authors.initials: R
authors.lastname: Downes
authors.forename: C A
authors.initials: CA
authors.lastname: Gauthier
mesh_terms: D002452:Cell Count; D003201:Computers; D004728:Endothelium, Corneal / Q000473:pathology; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000601:surgery*; D017060:Patient Satisfaction; D018903:Photorefractive Keratectomy / Q000295:instrumentation*; D011183:Postoperative Complications / Q000209:etiology; D012029:Refraction, Ocular; D016896:Treatment Outcome; D014786:Vision Disorders / Q000209:etiology; D014792:Visual Acuity / Q000502:physiology