title: Corneal endothelial cell loss 9 years after excimer laser keratorefractive surgery.
abstract: OBJECTIVE
  To determine the long-term changes in the corneal endothelium after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).
  
  
  METHODS
  Twenty-nine eyes (16 patients) received myopic LASIK or PRK, with intended correction to emmetropia. Central endothelial photographs were taken before and 9 years after surgery and were analyzed by the same masked investigator after appropriate calibration for magnification. Comparisons were made by using generalized estimating equation models to account for any correlation between fellow eyes of the same patient. The annual exponential rate of cell loss was compared with cell loss during a 10-year period in 42 normal (unoperated) corneas of 42 subjects.
  
  
  RESULTS
  Endothelial cell density 9 years after LASIK and PRK had decreased by 5.3% from preoperative density (P < .001), whereas coefficient of variation of cell area (P = .24) and percentage of hexagonal cells (P = .19) did not change. The mean annual rate of cell loss after refractive surgery (0.6% [standard deviation, 0.8%]) was not different from that in normal corneas (0.6% [0.5%], P = .88; minimum detectable difference = 0.5%; alpha = .05; beta = .20).
  
  
  CONCLUSIONS
  Laser in situ keratomileusis and PRK had no long-term effect on the corneal endothelium. Corneas that have undergone LASIK or PRK can be considered for use as donors for posterior lamellar keratoplasty procedures.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905, USA. patel.sanjay@mayo.edu
authors.forename: Sanjay V
authors.initials: SV
authors.lastname: Patel
authors.forename: William M
authors.initials: WM
authors.lastname: Bourne
mesh_terms: D000328:Adult; D002452:Cell Count; D003316:Corneal Diseases / Q000209:etiology*; D004728:Endothelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D018903:Photorefractive Keratectomy / Q000379:methods*; D011183:Postoperative Complications; D055815:Young Adult