title: Effect of high-altitude exposure on myopic laser in situ keratomileusis.
abstract: OBJECTIVE
  To study the effect of high-altitude exposure on visual acuity after myopic laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Aconcagua, Mendoza, Argentina.
  
  
  METHODS
  In the early postoperative period after uneventful myopic LASIK, 2 physicians prospectively assessed their visual acuity during an ascent of Aconcagua (22841 feet). The distance uncorrected visual acuity (UCVA) and peripheral oxygenation were measured at approximately every 2000 feet of altitude.
  
  
  RESULTS
  Both climbers developed a moderate loss of distance UCVA but described normal near and pinhole acuity consistent with a myopic shift. The distance UCVA diminished to 20/100 in the right eye and 20/125 in the left eye of Climber A and to 20/160 and 20/30, respectively, of Climber B. The vision loss worsened with increased altitude, duration of exposure, and decreased peripheral oxygenation. One week after the climb, the manifest refraction demonstrated a small myopic shift in both eyes of Climber A; these subsequently resolved.
  
  
  CONCLUSIONS
  Two climbers, 8 and 14 weeks after myopic LASIK, experienced vision loss consistent with a temporary myopic shift in the refractive error with ascent to high altitude. Climbers who have LASIK, particularly those in the early postoperative period, should be prepared for visual acuity fluctuations with high-altitude exposure.
authors.forename: D A
authors.initials: DA
authors.lastname: Boes
authors.forename: A K
authors.initials: AK
authors.lastname: Omura
authors.forename: M J
authors.initials: MJ
authors.lastname: Hennessy
mesh_terms: D000328:Adult; D000531:Altitude; D001274:Atmospheric Pressure; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D006956:Hyperopia / Q000209:etiology* / Q000503:physiopathology; D007429:Intraocular Pressure; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology; D014792:Visual Acuity