title: Off-axis refraction and aberrations following conventional laser in situ keratomileusis.
abstract: OBJECTIVE
  To investigate off-axis refraction and aberrations following conventional laser in situ keratomileusis (LASIK) for myopia and hypermetropia.
  
  
  METHODS
  School of Optometry, Queensland University of Technology, Australia.
  
  
  METHODS
  Using an autorefractor, off-axis refractions were analyzed along the horizontal visual field between 35 degrees nasally and 35 degrees temporally in 1 eye each of 15 emmetropic subjects (-0.50 to +0.50 diopters [D]), 6 myopic subjects (-2.25 to -6.50 D), 6 hyperopic subjects (+1.50 to +3.00 D), 6 myopic LASIK patients (presurgical refraction -2.75 to -9.00 D), and 6 hyperopic LASIK patients (presurgical refraction +0.75 to +2.00 D). Wavefront sensing measured off-axis higher-order aberrations in 2 myopic LASIK patients.
  
  
  RESULTS
  In myopic LASIK, the mean spherical components of refraction M became highly myopic away from the center of the visual field; in emmetropic and untreated myopic eyes, there were relatively small myopic shifts and hyperopic shifts, respectively. Off-axis 90-degree to 180-degree astigmatisms J180 in myopic LASIK subjects were greater than in untreated subjects. In hyperopic LASIK, there were mainly hyperopic shifts in M, opposite the direction in emmetropic and untreated hyperopic subjects. Off-axis J180 was less than in emmetropic and untreated hyperopic subjects. Some hyperopic LASIK patients had greater off-axis 45-degree to 135-degree astigmatisms J45 than patients in the other groups. In 2 myopic LASIK patients, Zernike root-mean-square 4th-order aberrations were higher than in the near-emmetropia group because of higher levels of positive spherical aberration.
  
  
  CONCLUSIONS
  Off-axis aberrations can be dramatically affected by conventional myopic and hyperopic LASIK. In myopic LASIK, the increased off-axis refractive errors may have adverse effects on peripheral visual tasks that are dependent on off-axis refractive errors. The relatively low off-axis refractive errors in hyperopic LASIK patients may improve peripheral visual tasks.
authors.affiliation: Shandong Provincial Hospital, Jinan, China.
authors.forename: Luxin
authors.initials: L
authors.lastname: Ma
authors.forename: David A
authors.initials: DA
authors.lastname: Atchison
authors.forename: W Neil
authors.initials: WN
authors.lastname: Charman
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D006801:Humans; D006956:Hyperopia / Q000601:surgery; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000209:etiology*; D014794:Visual Fields / Q000502:physiology