title: The effect of photorefractive keratectomy on the corneal endothelium.
abstract: OBJECTIVE
  The authors prospectively investigated the effect of excimer laser photorefractive keratectomy (PRK) for myopia on the corneal endothelium.
  
  
  METHODS
  Quantitative computer-assisted morphometric analysis of central and peripheral corneal endothelial cells was performed on 142 myopic eyes before and at 3 months, 1 year, and 2 years after PRK. The mean age of the subjects was 37 years (range, 21-66 years). Ninety-one (64%) of them had a history of contact lens wear. Mean attempted correction was -3.9 diopters (range, -1.6 to -6.0 diopters).
  
  
  RESULTS
  The mean preoperative endothelial cell density was 2660 cells/mm2 centrally and 2776 cells/mm2 peripherally. There was no change in central endothelial cell density at any of the postoperative examinations. The peripheral cell density decreased 4.1% (P = 0.003) at 3 months and 6.2% (P = 0.0001) at 1 year. However, the peripheral cell density was not significantly different from the preoperative value at 2 years. The peripheral coefficient of variation of cell size was 7.8% lower 2 years postoperatively than it was preoperatively, and this improvement was attributable to cessation of contact lens wear after PRK. The decrease in peripheral endothelial cell density at 1 year correlated with the amount of attempted correction, but there was no correlation between attempted correction and the change in central or peripheral endothelial cell density 2 years postoperatively.
  
  
  CONCLUSIONS
  For the correction of up to 6.0 D of myopia, PRK causes no detectable changes in central corneal endothelial cell density, but it does cause a transient, modest loss of peripheral corneal endothelial cells at 1 year. Variations in endothelial cell shape caused by contact lens wear resolve after PRK.
authors.affiliation: Department of Ophthalmology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: R D
authors.initials: RD
authors.lastname: Stulting
authors.forename: K P
authors.initials: KP
authors.lastname: Thompson
authors.forename: G O
authors.initials: GO
authors.lastname: Waring
authors.forename: M
authors.initials: M
authors.lastname: Lynn
mesh_terms: D000328:Adult; D000368:Aged; D002452:Cell Count; D048429:Cell Size; D003261:Contact Lenses; D003315:Cornea / Q000601:surgery*; D004728:Endothelium, Corneal / Q000166:cytology / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy; D011446:Prospective Studies