title: Evaluation of the retinal nerve fiber layer measurements, after photorefractive keratectomy and laser in situ keratomileusis, using scanning laser polarimetry (GDX VCC).
abstract: BACKGROUND
  To evaluate the impact of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK), on retinal nerve fiber layer (RNFL) measurements, by means of scanning laser polarimetry (SLP) GDx VCC (with variable corneal compensation).
  
  
  METHODS
  Two groups of 119 myopic patients each were treated by PRK and LASIK respectively; one eye of each patient was randomly selected for the study. RNFL measurements (around the entire calculation circle) was performed in all eyes 1 day before and 1, 3, 6 and 12 months after treatment by using SLP GDx VCC. Corneal compensation was performed in all eyes preoperatively, and in every examination step postoperatively, in order to neutralize the new corneal birefringence.
  
  
  RESULTS
  No statistical differences were found between the PRK and LASIK groups, in all preoperative and postoperative RNFL measurements. Only the p values for CCT and mean K-readings preoperatively were statistically significant.
  
  
  CONCLUSIONS
  PRK and LASIK do not seem to influence the RNFL measurements at 1st, 3rd, 6th and 12th postoperative months when measured with SLP GDx VCC. The corneal compensation reset is necessary in every step of the examination in order to have reproducible results.
authors.affiliation: Department of Ophthalmology & Eye Institute of Thrace, Democritus University of Thrace, Alexandroupolis, Greece. aaristeidou@yahoo.gr
authors.forename: Antonios P
authors.initials: AP
authors.lastname: Aristeidou
authors.forename: Georgios
authors.initials: G
authors.lastname: Labiris
authors.forename: Eleftherios I
authors.initials: EI
authors.lastname: Paschalis
authors.forename: Nikitas C
authors.initials: NC
authors.lastname: Foudoulakis
authors.forename: Stavrenia C
authors.initials: SC
authors.lastname: Koukoula
authors.forename: Vassilios P
authors.initials: VP
authors.lastname: Kozobolis
mesh_terms: D000293:Adolescent; D000328:Adult; D003315:Cornea / Q000601:surgery; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D009412:Nerve Fibers / Q000473:pathology*; D018903:Photorefractive Keratectomy; D011184:Postoperative Period; D011446:Prospective Studies; D012165:Retinal Ganglion Cells / Q000473:pathology*; D057109:Scanning Laser Polarimetry; D055815:Young Adult