title: Effect of laser in situ keratomileusis on optic nerve head topography and retinal nerve fiber layer thickness.
abstract: OBJECTIVE
  To determine whether laser in situ keratomileusis (LASIK) produces significant changes in optic nerve head (ONH) topography and retinal nerve fiber layer (RNFL) thickness as measured by the Heidelberg Retina Tomograph (HRT) and to evaluate the potential neuroprotective effect of topical betaxolol on these changes.
  
  
  METHODS
  Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
  
  
  METHODS
  In this prospective randomized double-masked comparative case series, 34 patients having LASIK for myopia were randomly assigned to receive topical betaxolol 0.5% solution or placebo twice a day for 2 days before the procedure and 7 days after the procedure. Preoperative and postoperative (1 week and 1 and 3 months) images were made with the HRT. Four HRT parameters (rim area, rim volume, mean RNFL thickness, and cup shape measure) were analyzed in a masked fashion. The Student paired t test was used for statistical analysis.
  
  
  RESULTS
  No significant changes from baseline occurred in any HRT parameter in either patient group or when the patients were evaluated as a single group.
  
  
  CONCLUSIONS
  Laser in situ keratomileusis did not adversely affect ONH morphology or RNFL thickness as measured by HRT. Since no neural damage was detected, the potential neuroprotective effect of betaxolol could not be evaluated.
authors.affiliation: Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA. Jess.Whitson@UTSouthwestern.edu
authors.forename: Jess T
authors.initials: JT
authors.lastname: Whitson
authors.forename: James P
authors.initials: JP
authors.lastname: McCulley
authors.forename: H Dwight
authors.initials: HD
authors.lastname: Cavanagh
authors.forename: Julia
authors.initials: J
authors.lastname: Song
authors.forename: R Wayne
authors.initials: RW
authors.lastname: Bowman
authors.forename: Lars
authors.initials: L
authors.lastname: Hertzog
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000328:Adult; D000368:Aged; D015784:Betaxolol / Q000008:administration & dosage; D019610:Cytoprotection / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007429:Intraocular Pressure / Q000187:drug effects; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D009412:Nerve Fibers / Q000187:drug effects / Q000473:pathology*; D009898:Optic Disk / Q000187:drug effects / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000209:etiology / Q000517:prevention & control; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000473:pathology*
chemical_list: D000319:Adrenergic beta-Antagonists; D015784:Betaxolol