title: Objective quality of vision in presbyopic and non-presbyopic patients after pseudoaccommodative advanced surface ablation.
abstract: OBJECTIVE
  To analyze the objective quality of vision at 6 months postoperatively after pseudoaccommodative (presbyopic) advanced surface ablation (PASA).
  
  
  METHODS
  The study comprised 62 eyes of 35 patients with 6-month follow-up that underwent primary or secondary treatments using PASA. Pre- and postoperative results of distance and near uncorrected visual acuity (UCVA), spherical aberration (coefficient of the Z12 Zernike polynomial), and the asphericity (Q) index were reviewed. The corresponding wavefront maps (total, low, and high order aberrations) and the corresponding point spread function and modulation transfer function (MTF) were also calculated.
  
  
  RESULTS
  Our results show that PASA improves distance and near mean UCVA, increases negative spherical aberration and negative asphericity index, and improves the corresponding MTF.
  
  
  CONCLUSIONS
  Pseudoaccommodative advanced surface ablation is a promising approach for the surgical correction of presbyopia with distance refractive error (myopia and hyperopia with or without astigmatism). This PASA technique could theoretically be used in non-presbyopic patients with refractive error or post cataract patients with monofocal intraocular lenses. The increase in negative spherical aberration and asphericity/eccentricity index seems to increase the depth of focus of the eye, improving the near vision and compensating the age-related lens changes. Rather than creating a multifocal cornea, PASA appears to create an improved aspheric (prolate) ablation profile.
authors.affiliation: CVL, Laser Vision Correction, Puebla, Pue, México. info@cvlaser.com
authors.forename: Roberto
authors.initials: R
authors.lastname: Cantú
authors.forename: Marco A
authors.initials: MA
authors.lastname: Rosales
authors.forename: Eduardo
authors.initials: E
authors.lastname: Tepichín
authors.forename: Andrée
authors.initials: A
authors.lastname: Curioca
authors.forename: Víctor
authors.initials: V
authors.lastname: Montes
authors.forename: J Gustavo
authors.initials: JG
authors.lastname: Ramirez-Zavaleta
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D005500:Follow-Up Studies; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology / Q000601:surgery*; D054018:Lasers, Excimer; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D011184:Postoperative Period; D011305:Presbyopia / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*