title: The changes of posterior corneal surface and high-order aberrations after refractive surgery in moderate myopia.
abstract: OBJECTIVE
  To compare forward shift of posterior corneal surface and higher-order aberration (HOA) changes after LASIK, LASEK, and wavefront-guided LASEK surgery in moderate myopia
  
  
  METHODS
  One hundred eighty four eyes undergoing LASIK, LASEK and wavefront-guided LASEK with VISX STAR S4 were included in this study. The posterior corneal elevation was measured with Orbscan before, 2 and 4 months after surgery. Changes of the elevation were assessed using the difference map generated from preoperative and postoperative elevation maps. The values of higher-order aberrations were evaluated preoperatively and 2 months postoperatively with Wavefront aberrometer.
  
  
  RESULTS
  The posterior corneal surface displayed forward shift of 27.2+/-11.45 micrometer, 24.3+/-9.76 micrometer in LASIK group, 23.4+/-10.5 micrometer, 23.6+/10.55 micrometer in LASEK group, 24.0+/-14.95 micrometer, 28.4+/-14.72 micrometer in wavefront-guided LASEK group at 2 months and 4 months, respectively. There were no statistically significant differences among those three groups, and between 2 and 4 months. The root mean score (RMS) of HOA was increased after LASIK and LASEK (p=0.000, p=0.000, respectively). The mean change of HOA-RMS was significantly smaller in wavefront-guided LASEK than LASIK or LASEK (p=0.000, p=0.000, respectively, Bonferroni-corrected).
  
  
  CONCLUSIONS
  The changes of posterior corneal surface forward shift showed no difference among LASIK, LASEK and wavefront-guided LASEK in moderate myopia. HOAs were significantly increased after LASIK and LASEK. The changes of HOAs were significant smaller in wavefront-guided LASEK than LASIK or LASEK.
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, and Seoul Artificial Eye Center, Seoul National University Hospital Clinical Research Institute, Korea.
authors.forename: Min Joung
authors.initials: MJ
authors.lastname: Lee
authors.forename: Sang Mok
authors.initials: SM
authors.lastname: Lee
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Lee
authors.forename: Won Ryang
authors.initials: WR
authors.lastname: Wee
authors.forename: Jin Hak
authors.initials: JH
authors.lastname: Lee
authors.forename: Mee Kum
authors.initials: MK
authors.lastname: Kim
mesh_terms: D000328:Adult; D019781:Corneal Topography; D006801:Humans; D009216:Myopia / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D011184:Postoperative Period; D054140:Refractive Surgical Procedures; D012720:Severity of Illness Index