title: Postoperative Changes in Corneal Epithelial and Stromal Thickness Profiles After Photorefractive Keratectomy in Treatment of Myopia.
abstract: OBJECTIVE
  To study the corneal epithelial and stromal thickness profile changes after photorefractive keratectomy (PRK) for myopia.
  
  
  METHODS
  Retrospective analysis of the postoperative corneal epithelial and stromal thickness profile changes in 46 left eyes of 46 patients treated with PRK for myopia. Corneal and epithelial thickness maps within the central 6 mm were obtained by anterior segment spectral-domain optical coherence tomography preoperatively and at 1, 3, and 6 months postoperatively. Stromal thickness was calculated by subtracting the epithelial thickness from the total corneal thickness. Correlations between postoperative thickness changes and the amount of correction, treatment zone, and preoperative epithelial thickness were analyzed.
  
  
  RESULTS
  Compared to preoperative values, the central 2 mm and the paracentral 2- to 5-mm zone epithelium was 5.20 ± 3.43 and 5.72 ± 3.30 µm thicker, respectively, at 3 months postoperatively (P < .05). No significant difference was detected between 3 and 6 months postoperatively. The stromal thickness did not change between 1 and 6 months postoperatively. The spherical equivalent (SE) changed from -2.82 ± 1.54 diopters (D) preoperatively to -0.06 ± 0.42 D at 1 month postoperatively, and remained stable thereafter. There was a trend toward greater epithelial thickening with a larger amount of programmed SE correction, smaller treatment zone, and thinner preoperative epithelium. No correlation between epithelial thickness change and postoperative change in refraction was detected.
  
  
  CONCLUSIONS
  The corneal epithelial thickness increased after PRK up to 3 months postoperatively. It was affected by the amount of myopia treated, treatment zone, and preoperative epithelial thickness. The postoperative epithelial thickening did not affect the refractive outcomes.
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Chen
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Stojanovic
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Liu
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Chen
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhou
authors.forename: Tor Paaske
authors.initials: TP
authors.lastname: Utheim
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000473:pathology*; D019781:Corneal Topography; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D009929:Organ Size; D018903:Photorefractive Keratectomy / Q000379:methods*; D011184:Postoperative Period; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence; D055815:Young Adult