title: Long-term keratocyte deficits in the corneal stroma after LASIK.
abstract: OBJECTIVE
  To determine changes in keratocyte density up to 3 years after LASIK.
  
  
  METHODS
  Prospective, nonrandomized, comparative trial.
  
  
  METHODS
  Seventeen eyes of 11 patients received LASIK with a planned 180-microm flap to correct refractive errors between -2.0 diopters (D) and -11.0 D (mean, -6.56+/-2.44).
  
  
  METHODS
  Corneas were examined by using confocal microscopy before LASIK and 1, 3, 6, 12, 24, and 36 months after LASIK. Bright objects that resembled keratocyte nuclei were manually counted by a masked observer. Cell densities were determined in anterior and posterior halves of the stromal flap, anterior and posterior halves of the 100-microm-thick layer immediately behind the ablation (retroablation layer), and the posterior third of the stroma. The region of stroma that was ablated (as measured 1 month after LASIK) was omitted from preoperative analysis. Cell densities after LASIK were compared (using1-factor repeated-measures analysis of variance) with densities in the corresponding layer of the normal preoperative stroma (which served as its own control).
  
  
  METHODS
  Corneal keratocyte density.
  
  
  RESULTS
  Before LASIK, keratocyte densities in the anterior and posterior stromal flap and the anterior retroablation layer were 34 818+/-5108 cells/mm(3) (mean +/- SD), 25 390+/-4045 cells/mm(3), and 21 328+/-2980 cells/mm(3), respectively, and densities in these layers decreased 14% to 20% at 1 month after LASIK (P<0.001). Keratocyte densities in these layers remained stable at 3 and 6 months, and then gradually decreased further (P<0.001) to 26% to 36% below pre-LASIK densities by 3 years. Keratocyte densities in the remaining stromal layers did not change after LASIK.
  
  
  CONCLUSIONS
  Keratocyte densities in the stromal flap and in the anterior retroablation layer decrease during the first 6 months after LASIK and then decrease further during the next 2.5 years. Further studies on these patients and others are warranted to confirm these findings and learn their significance.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota 55905, USA. eric.jay@mayo.edu
authors.forename: Jay C
authors.initials: JC
authors.lastname: Erie
authors.forename: Cherie B
authors.initials: CB
authors.lastname: Nau
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; D001251:Astigmatism / Q000601:surgery; D002452:Cell Count; D003319:Corneal Stroma / Q000473:pathology*; D005260:Female; D005347:Fibroblasts / Q000473:pathology*; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D011183:Postoperative Complications; D011446:Prospective Studies; D013524:Surgical Flaps / Q000473:pathology*