title: Keratocyte density in the human cornea after photorefractive keratectomy.
abstract: OBJECTIVE
  To perform a quantitative analysis of keratocyte density in human corneas after photorefractive keratectomy (PRK).
  
  
  METHODS
  In a prospective comparative trial, 24 eyes of 14 patients received PRK to correct refractive errors of between -1.25 diopters (D) and -5.75 D. Corneas were examined by using confocal microscopy before and 1 day, 5 days, and 1, 3, 6, 12, 24, and 36 months after PRK. Keratocyte nuclei were counted in 5 stromal layers in 3 to 6 scans per eye per visit. Keratocyte density in each layer post-PRK was compared with the density in the corresponding layer of the pre-PRK full stroma (included stroma that would later be photoablated) and the pre-PRK future unablated stroma (thickness adjusted by omitting the future ablation depth) (Bonferroni-adjusted paired t test).
  
  
  RESULTS
  Keratocyte density in the anterior 10% of the post-PRK stroma decreased by 25% (P =.002), 41% (P<.001), 40% (P<.001), 43% (P<.001), and 45% (P<.001) at 3, 6, 12, 24, and 36 months compared with the anterior 10% of the pre-PRK full stroma and was reduced by 15% at 36 months (P =.02) compared with the anterior 10% of the pre-PRK future unablated stroma.
  
  
  CONCLUSIONS
  After PRK, keratocyte density in the anterior stroma is not restored to the high-density levels found in the preoperative stroma.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, Minn 55905, USA. erie.jay@mayo.edu
authors.forename: Jay C
authors.initials: JC
authors.lastname: Erie
authors.forename: Sanjay V
authors.initials: SV
authors.lastname: Patel
authors.forename: Jay W
authors.initials: JW
authors.lastname: McLaren
authors.forename: David O
authors.initials: DO
authors.lastname: Hodge
authors.forename: William M
authors.initials: WM
authors.lastname: Bourne
mesh_terms: D000328:Adult; D002452:Cell Count; D003319:Corneal Stroma / Q000473:pathology*; D005260:Female; D005347:Fibroblasts / Q000473:pathology*; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009216:Myopia / Q000473:pathology / Q000601:surgery; D018903:Photorefractive Keratectomy; D011446:Prospective Studies; D013997:Time Factors