title: Changes in ocular response analyzer parameters after LASIK.
abstract: OBJECTIVE
  To investigate changes in Ocular Response Analyzer parameters after myopic LASIK.
  
  
  METHODS
  Thirty myopic patients (60 eyes) undergoing bilateral LASIK were studied prospectively. Corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) measurements were obtained with the Ocular Response Analyzer before and after LASIK. Central corneal thickness and corneal flap thickness were also measured with optical coherence tomography.
  
  
  RESULTS
  Compared with preoperative baseline values, corneal hysteresis, corneal resistance factor, IOPg, IOPcc, and central corneal thickness decreased postoperatively (P<.01). Corneal hysteresis (CH), corneal resistance factor (CRF), IOPg, IOPcc, and central corneal thickness (CCT) increased between 10 days and 3 months (post-hoc, P<.05). (The differences between the preoperative values and those at 3 months postoperatively are denoted by Delta.) The correlation of the ablation depth was stronger for DeltaCRF (r=0.457) than for DeltaCH (r=0.271). DeltaCH was negatively correlated to flap thickness (r=-0.361) and the ratio of flap thickness to preoperative central corneal thickness (r=-0.442) whereas DeltaCRF was not. DeltaCH was positively correlated with DeltaIOPcc, and DeltaCRF was positively correlated with DeltaIOPg. DeltaIOPg was positively correlated with DeltaCCT whereas DeltaIOPcc was not.
  
  
  CONCLUSIONS
  Corneal biomechanical properties measured by corneal hysteresis and corneal resistance factor were decreased at 10 days after LASIK. Minimal recovery (approximately 10% of the changes) was achieved by 3 months. The changes in biomechanical properties may affect IOP measurement.
authors.affiliation: Wenzhou Medical College, Wenzhou, Zhejiang, China.
authors.forename: Shihao
authors.initials: S
authors.lastname: Chen
authors.forename: Ding
authors.initials: D
authors.lastname: Chen
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
authors.forename: Fan
authors.initials: F
authors.lastname: Lu
authors.forename: Qinmei
authors.initials: Q
authors.lastname: Wang
authors.forename: Jia
authors.initials: J
authors.lastname: Qu
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000502:physiology*; D004547:Elastic Tissue / Q000502:physiology*; D004548:Elasticity / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure; D020731:Keratomileusis, Laser In Situ; D009216:Myopia / Q000601:surgery*; D011446:Prospective Studies; D013524:Surgical Flaps / Q000473:pathology; D055815:Young Adult