title: [Computational simulation of customized photorefractive surgery and precision of correction related to different order aberrations].
abstract: OBJECTIVE
  To develop and implement an algorithm for simulation of photorefractive surgery. It is well known that many flying-spot lasers in the market have limitations in correcting higher order aberrations, but there is little quantitative information about errors related to aberration complexity.
  
  
  METHODS
  By applying known surfaces described by Zernike polynomials of different orders it was possible to simulate several target surfaces that may well resemble in vivo cases of refractive surgery candidates. An algorithm that uses the mathematical concept of convolution was implemented and several simulated surfaces were tested, ranging from low order aberrations (sphere-cylinder) to 10th order aberrations, (high orders of coma, spherical aberration, trefoil, etc).
  
  
  RESULTS
  the results show that the laser profile and diameter are critical factors when considering the correction of higher order aberrations.
  
  
  CONCLUSIONS
  Not all aberrations of the same high order induce the same amount of error - spherical aberrations are shown to be far more difficult to correct than higher order aberrations related to angular frequency.
authors.affiliation: Laboratório de Optica Oftálmica, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brasil. lavcf@ifsc.usp.br
authors.forename: Luis Alberto
authors.initials: LA
authors.lastname: Vieira de Carvalho
mesh_terms: D000465:Algorithms; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery; D003198:Computer Simulation; D003315:Cornea / Q000503:physiopathology / Q000601:surgery; D019781:Corneal Topography; D006801:Humans; D054018:Lasers, Excimer; D008962:Models, Theoretical; D018903:Photorefractive Keratectomy / Q000379:methods*; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000503:physiopathology; D054140:Refractive Surgical Procedures; D012720:Severity of Illness Index