title: Comparison of tear secretion and tear film instability after photorefractive keratectomy and laser in situ keratomileusis.
abstract: OBJECTIVE
  To evaluate and compare tear secretion and tear film instability following photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Department of Ophthalmology, Yonsei University School of Medicine, Seoul, Korea.
  
  
  METHODS
  In a prospective study, 36 eyes (21 patients) had PRK and 39 eyes (25 patients) had LASIK to correct myopia. Tear secretion and tear film instability were tested preoperatively and 3 and 6 months postoperatively using Schirmer test values, tear breakup time (BUT) scores, and tear osmolarity.
  
  
  RESULTS
  Six months after surgery, the change in Schirmer test values from preoperative levels was -14.57% +/- 6.39% (SD) in the PRK eyes and -23.40% +/- 5.94% in the LASIK eyes and the change in BUT scores, -12.54% +/- 8.28% and -18.79% +/- 13.01%, respectively. The change in tear osmolarity was 14.95% +/- 6.46% and 35.63% +/- 8.51%, respectively.
  
  
  CONCLUSIONS
  The decrease in tear secretion was greater after LASIK than after PRK at 6 months. Proper treatment of dry eye is required after LASIK and PRK, particularly in the LASIK postoperative period.
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Seoul, South Korea. jblee88@yumc.yonsei.ac.kr
authors.forename: J B
authors.initials: JB
authors.lastname: Lee
authors.forename: C H
authors.initials: CH
authors.lastname: Ryu
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: E K
authors.initials: EK
authors.lastname: Kim
authors.forename: H B
authors.initials: HB
authors.lastname: Kim
mesh_terms: D000328:Adult; D015352:Dry Eye Syndromes / Q000503:physiopathology / Q000517:prevention & control; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D007765:Lacrimal Apparatus / Q000378:metabolism*; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D009994:Osmolar Concentration; D018903:Photorefractive Keratectomy; D011184:Postoperative Period; D011446:Prospective Studies; D013500:Surface Tension; D013666:Tears / Q000378:metabolism*