title: Higher-order aberrations of anterior and posterior corneal surfaces in patients with keratectasia after LASIK.
abstract: OBJECTIVE
  We investigated higher-order aberrations (HOAs) of the anterior and posterior corneal surfaces in patients with keratectasia after LASIK.
  
  
  METHODS
  The subjects comprised four groups: 12 eyes with keratectasia after LASIK, 30 eyes following LASIK without keratectasia, 30 keratoconic eyes, and 30 normal eyes. Corneal HOAs due to the anterior and posterior corneal surfaces for 6-mm pupils (root mean square [μm]) were obtained using a Scheimpflug-based corneal tomographer and compared among the four groups.
  
  
  RESULTS
  There were significant differences in total HOAs of the anterior and posterior corneal surfaces (mean ± SD) in the keratectasia (2.49 ± 1.37 and 0.83 ± 0.57), keratoconus (4.50 ± 2.57 and 1.18 ± 0.65), LASIK (0.84 ± 0.25 and 0.14 ± 0.04), and normal (0.52 ± 0.15 and 0.17 ± 0.06) groups except for between keratoconus and keratectasia at the posterior surface. Keratectasia and keratoconus showed similar coma-dominant patterns at both surfaces, and there were no significant differences in the Zernike terms between both groups except for the total HOAs and coma aberration at the anterior surface.
  
  
  CONCLUSIONS
  Although flap creation and laser ablation were supposed to center on the primary line of sight in LASIK, keratectasia after LASIK showed coma-dominant HOAs at both corneal surfaces. This suggests that the cornea in keratectasia has optical properties similar to those in keratoconus.
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maeda
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nakagawa
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kosaki
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Shizuka
authors.initials: S
authors.lastname: Koh
authors.affiliation: Research Institute, Optics Laboratory, Topcon Corporation, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Saika
authors.affiliation: Department of Applied Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujikado
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
mesh_terms: D057128:Aberrometry; D000328:Adult; D057108:Corneal Wavefront Aberration / Q000175:diagnosis*; D004108:Dilatation, Pathologic / Q000175:diagnosis / Q000209:etiology; D004728:Endothelium, Corneal / Q000473:pathology*; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007640:Keratoconus / Q000175:diagnosis* / Q000209:etiology; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery; D010781:Photography; D011183:Postoperative Complications; D012189:Retrospective Studies
keywords: LASIK; aberration; cornea; keratectasia; keratoconus