title: [The apoptosis and proliferation after photorefractive keratectomy].
abstract: OBJECTIVE
  To search the correlation between the apoptosis and proliferation of keratocytes and investigate the influence of phototherapeutic keratectomy (PTK) and mechanical epithelial scrape (MES) on keratocyte apoptosis and proliferation.
  
  
  METHODS
  Rabbit corneas received photorefractive keratectomy (PRK, -9.9 diopters, 6 mm diameter). Animals were evaluated subsequently up to 6 months after surgery by in vivo confocal microscopy. Corneas were prepared for H.E. staining, corneal cell apoptosis was evaluated by terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) to detect DNA fragmentation.
  
  
  RESULTS
  Loss of keratocytes and keratocyte death were found anteriorly in the remaining stroma at 4h after PRK. Activated keratocytes observed by confocal microscopy repopulated within 1 month. A significant elevation of apoptosis was detected in keratocytes and epithelium at 4h, 3d, 1m after PRK. The level of keratocyte apoptosis was parallel to the loss of keratocytes at the early stage and was correlated with keratocyte proliferation in the later stage, PTK-PRK was associated with lower levels of central corneal apoptosis and activated keratocytes than MES-PRK.
  
  
  CONCLUSIONS
  It is suggested that the loss of keratocytes and keratocyte apoptosis be correlated with keratocyte activation and proliferation, which may result in haze and regression after PRK, and PTK-PRK induce lower level of early keratocyte apoptosis and late keratocyte activation than MES-PRK.
authors.affiliation: Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing 100730.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: G
authors.initials: G
authors.lastname: Pang
authors.forename: S
authors.initials: S
authors.lastname: Zhan
authors.forename: Y
authors.initials: Y
authors.lastname: Jin
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: W
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery; D005260:Female; D020287:In Situ Nick-End Labeling; D054018:Lasers, Excimer; D008297:Male; D018613:Microscopy, Confocal; D018903:Photorefractive Keratectomy; D011817:Rabbits