title: Essential opaque bubble layer elimination with novel LASIK flap settings in the FS200 Femtosecond Laser.
abstract: BACKGROUND
  The purpose of this study is to evaluate the extent and incidence of opaque bubble layer (OBL) using laser-assisted in situ keratomileusis (LASIK) flaps created with the Alcon/WaveLight® FS200 femtosecond laser as a result of a recent change in flap programming parameters aiming to reduce further the incidence and extent of OBL.
  
  
  METHODS
  Intraoperative digital images of flaps from 36 consecutive patients (72 eyes) subjected to bilateral femtosecond-assisted LASIK were analyzed using a proprietary computerized technique. The incidence and extent of OBL was measured and reported as a percentage of the entire flap area. Flap creation was performed with a 1.7 mm wide canal, implemented as an updated design intended to reduce the extent of OBL (group A). The same OBL parameters were investigated and compared in an age-matched and procedure-matched patients in whom the previous standard setting of a 1.3 mm wide canal was implemented (group B).
  
  
  RESULTS
  In group A, the average extent of OBL was 3.69% of the flap area (range 0%-11.34%). In group B, the respective values were 6.06% (range 0%-20.24%). We found the difference to be statistically significant (one-tailed P = 0.00452).
  
  
  CONCLUSIONS
  This study suggests that there is a significant reduction in the incidence and extent of OBL when novel LASIK flap ventilation canal parameters of width and spot line separation are used.
authors.affiliation: Laservision.gr Eye Institute, Athens, Greece ; New York University School of Medicine, New York, NY, USA.
authors.forename: A John
authors.initials: AJ
authors.lastname: Kanellopoulos
authors.forename: George
authors.initials: G
authors.lastname: Asimellis
keywords: Alcon/WaveLight FS200; bladeless laser-assisted in situ keratomileusis; femtosecond laser flap; opaque bubble layer; spot line separation