title: Ascorbic acid levels in human tears after photorefractive keratectomy, transepithelial photorefractive keratectomy, and laser in situ keratomileusis.
abstract: OBJECTIVE
  To investigate the level of ascorbic acid in human tear fluid after photorefractive keratectomy (PRK), transepithelial PRK, and laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Departments of Ophthalmology and Biochemistry, School of Medicine, Gazi University, Ankara, Turkey.
  
  
  METHODS
  Twenty patients (7 women and 13 men) were included in this study. Traditional PRK with epithelial scraping by a blunt spatula followed by surface ablation (7 eyes), transepithelial PRK (7 eyes), or LASIK (6 eyes) was performed. Tears were collected preoperatively and 1 and 5 days postoperatively. Ascorbic acid levels were measured using 2-4 dinitrophenylhydrazine.
  
  
  RESULTS
  Ascorbic acid levels in the tear fluid were decreased significantly 1 day after PRK, transepithelial PRK, and LASIK (P <.05). On the fifth day, the ascorbic acid levels were significantly lower than preoperatively in all groups.
  
  
  CONCLUSIONS
  After PRK, transepithelial PRK, and LASIK, the ascorbic acid levels of the tear fluid decreased significantly. Because ascorbic acid is the major scavenger of superoxide radicals in tears, topical ascorbic acid therapy may help eliminate the harmful effect of free radicals from excimer laser surgery.
authors: Department of Biochemistry, Gazi University School of Medicine, Ankara, Turkey. ayseb@med.gazi.edu.tr
authors: A
authors: A
authors: Bilgihan
authors: K
authors: K
authors: Bilgihan
authors: Y
authors: Y
authors: Toklu
authors: O
authors: O
authors: Konuk
authors: O
authors: O
authors: Yis
authors: B
authors: B
authors: Hasanreisoğlu
mesh_terms: D000328:Adult; D001205:Ascorbic Acid / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism / Q000601:surgery; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000378:metabolism / Q000601:surgery; D018903:Photorefractive Keratectomy; D013666:Tears / Q000378:metabolism*
chemical_list: D001205:Ascorbic Acid