title: Early flap displacement after LASIK.
abstract: OBJECTIVE
  To evaluate the risks of flap displacement after LASIK.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  We included 41 845 consecutive adults who underwent LASIK surgery at Optical Express in the United Kingdom, including 81 238 eyes, of which 14 555 were hyperopic and 66 681 myopic or mixed astigmatic. We treated 57 241 eyes with the IntraLase FS-60 femtosecond laser and 23 997 with the Moria S.A. ONE Use-Plus automated microkeratome.
  
  
  METHODS
  We calculated the incidence of all flap displacements in the study population during an observational time period of ≥12 months after surgery. Independent variables were entered into logistic regression models to identify risk factors. Postoperative outcomes were assessed.
  
  
  METHODS
  The incidence and odds ratios (OR) of flap displacement in the study population and in categories of refractive error and flap surgery technique.
  
  
  RESULTS
  The incidence of flap displacements was 10 in 81 238 LASIK procedures (0.012%), including 8 hyperopic eyes (0.055%) and 2 myopic eyes (0.003%). All flap displacements occurred within 48 hours of surgery and none were preceded by ocular trauma. They were classified as "early flap displacements" (EFD). The incidence of EFD after microkeratome surgery was 0.033% (n = 8), and after femtosecond laser it was 0.003% (n = 2). In hyperopic eyes having microkeratome surgery, the incidence was 0.179% (n = 7). In a logistic regression model, the strongest predictor of EFD after LASIK was hyperopia, recording an OR of 19.29 (P<0.001). The OR of developing an EFD after microkeratomy was 10.53 times higher than after femtosecond laser (P<0.005). In hyperopes, the OR of an EFD was 18.87 times higher after microkeratomy than after femtosecond treatment. Four of 10 displaced flaps needed secondary surgery, and 1 eye lost 2 lines of best-corrected visual acuity.
  
  
  CONCLUSIONS
  The incidence of flap displacements during a 12-month period after LASIK was extremely low (0.012%). Although the small number of displacements with the femtosecond laser limits conclusions, the risk of EFD was higher after microkeratome surgery than femtosecond laser.
authors.affiliation: University of California San Francisco, Department of Ophthalmology, 10 Koret Way, K-301, San Francisco, CA 94143, USA.
authors.forename: Gerry
authors.initials: G
authors.lastname: Clare
authors.forename: Tara C B
authors.initials: TC
authors.lastname: Moore
authors.forename: Claire
authors.initials: C
authors.lastname: Grills
authors.forename: Antonio
authors.initials: A
authors.lastname: Leccisotti
authors.forename: Johnny E
authors.initials: JE
authors.lastname: Moore
authors.forename: Steve
authors.initials: S
authors.lastname: Schallhorn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003319:Corneal Stroma / Q000473:pathology*; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000601:surgery; D015994:Incidence; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D011183:Postoperative Complications; D012189:Retrospective Studies; D012307:Risk Factors; D013524:Surgical Flaps; D013529:Surgical Wound Dehiscence / Q000453:epidemiology / Q000209:etiology* / Q000601:surgery; D014792:Visual Acuity; D055815:Young Adult