title: Basement membrane and collagen deposition after laser subepithelial keratomileusis and photorefractive keratectomy in the leghorn chick eye.
abstract: OBJECTIVE
  To evaluate corneal scar formation and new collagen deposition after laser subepithelial keratomileusis (LASEK) compared with photorefractive keratectomy (PRK) in the leghorn chick corneal model.
  
  
  METHODS
  Leghorn chick corneas treated with LASEK surgery (using 20% ethanol for 30 seconds) or PRK were evaluated by indirect confocal immunofluorescence and transmission electron microscopy at 1, 2, 7, 14, and 28 days after surgery. New collagen deposition was determined by dichlorotriazinylaminofluorescein staining 2 and 4 weeks after surgery.
  
  
  RESULTS
  Laminin was detected around the basal layers during the immediate postoperative period and 4 weeks after LASEK surgery, and from day 2 onwards after PRK. Collagen III deposition in the cornea was about 3 times greater with PRK than with LASEK. The thickness of new collagen deposition at 4 weeks was 34 microm +/- 2.5 microm in the PRK group, which was significantly greater than that of the LASEK group (11 microm +/- 1 microm; P<.001).
  
  
  CONCLUSIONS
  Reduced subepithelial stromal tissue deposition was observed in LASEK-treated eyes compared with PRK-treated eyes. Postoperative preservation of the epithelial basement membrane and survival of epithelial cells in LASEK and possibly in epithelial laser in situ keratomileusis may contribute to this phenomenon.
  
  
  CONCLUSIONS
  An advantage of LASEK over PRK is the reduction of postoperative haze.
authors: Massachusetts Eye and Ear Infirmary and the Schepens Eye Research Institute, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA.
authors: Joel A D
authors: JA
authors: Javier
authors: Jae Bum
authors: JB
authors: Lee
authors: Hailton B
authors: HB
authors: Oliveira
authors: Jin-Hong
authors: JH
authors: Chang
authors: Dimitri T
authors: DT
authors: Azar