title: Time course of corneal biomechanical parameters after laser in situ keratomileusis.
abstract: OBJECTIVE
  To assess the time course of corneal biomechanics after laser in situ keratomileusis (LASIK).
  
  
  METHODS
  We examined 36 eyes of 20 consecutive patients undergoing LASIK for low to moderate myopia. We quantitatively assessed the values of corneal biomechanics characterized by corneal hysteresis (CH) and corneal resistance factor (CRF) using an Ocular Response Analyzer (Reichert Ophthalmic Instruments) before and 1 week, 1, 3, and 6 months after surgery. We carried out this measurement 3 times, and the average value was used for statistical analysis.
  
  
  RESULTS
  The CH was 10.6 +/- 1.7 (mean +/- SD) mm Hg preoperatively, and 8.6 +/- 1.2, 9.0 +/- 1.7, 9.0 +/- 1.4, and 8.9 +/- 1.5 mm Hg 1 week, 1, 3, and 6 months postoperatively, respectively. The CRF was 10.0 +/- 1.7 mm Hg preoperatively, and 7.3 +/- 1.5, 7.6 +/- 2.0, 7.8 +/- 1.6, and 7.7 +/- 1.6 mm Hg 1 week, 1, 3, and 6 months postoperatively, respectively. The variances of the data were statistically significant (p < 0.001 for both CH and CRF). Multiple comparisons demonstrated significant differences between measurements made before surgery and at all postoperative times (at 1 week and 1, 3, and 6 months; p < 0.001 for CH and CRF, Fisher's least significant difference test).
  
  
  CONCLUSIONS
  Over the study period, the largest changes in corneal biomechanical parameters occurred within 1 week after surgery, and these then became nearly stable. No progressive deterioration of the corneal biomechanics was observed at any time during the 6-month follow-up period.
authors.affiliation: Department of Ophthalmology, University of Kitasato School of Medicine, Sagamihara, Kanagawa, Japan. kamiyak-tky@umin.ac.jp
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kamiya
authors.forename: Kimiya
authors.initials: K
authors.lastname: Shimizu
authors.forename: Fumiko
authors.initials: F
authors.lastname: Ohmoto
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D011184:Postoperative Period; D013997:Time Factors