title: Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: a prospective fellow eye study.
abstract: OBJECTIVE
  To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK).
  
  
  METHODS
  Beyoğlu Eye Training and Research Hospital.
  
  
  METHODS
  Prospective comparative case series.
  
  
  METHODS
  Sixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10diopters (D) and a difference ≤0.50D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months).
  
  
  RESULTS
  Preoperative SE was similar in both groups (p=0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p<0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95±1.47 and 9.02±1.27, respectively (p=0.852), and the mean CRF values were 7.77±1.37 and 8.07±1.26, respectively (p=0.380).
  
  
  CONCLUSIONS
  CH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values.
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Alper
authors.initials: A
authors.lastname: Agca
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Engin Bilge
authors.initials: EB
authors.lastname: Ozgurhan
authors.affiliation: Istanbul Medeniyet University, Department of Ophthalmology, Istanbul, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Demirok
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Ercument
authors.initials: E
authors.lastname: Bozkurt
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey. Electronic address: h.ugurcelik@gmail.com.
authors.forename: Ugur
authors.initials: U
authors.lastname: Celik
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Ozkaya
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Ilker
authors.initials: I
authors.lastname: Cankaya
authors.affiliation: Beyoglu Eye Research and Training Hospital, Istanbul, Turkey.
authors.forename: Omer Faruk
authors.initials: OF
authors.lastname: Yilmaz
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery*; D019781:Corneal Topography; D004548:Elasticity; D005260:Female; D006244:Hardness; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D009216:Myopia / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D011446:Prospective Studies; D054140:Refractive Surgical Procedures / Q000379:methods*; D016896:Treatment Outcome; D014783:Viscosity
keywords: Biomechanics; Corneal hysteresis; Corneal resistance factor; LASIK; SMILE; Small incision lenticule extraction