title: Factors affecting laser in situ keratomileusis flap thickness: comparison of 2 microkeratome heads.
abstract: OBJECTIVE
  To identify the potential factors affect that affect the thickness of corneal flaps created using 2 different microkeratome heads.
  
  
  METHODS
  Care-Vision Laser Centers, Tel-Aviv, Israel.
  
  
  METHODS
  Retrospective comparative study.
  
  
  METHODS
  The study included eyes in which bilateral laser in situ keratomileusis (LASIK) was performed from January 1, 2005, to December 31, 2012, using an SBK-90 microkeratome head (Group 1) or an M2-90 microkeratome head (Group 2). Inclusion criteria were at least 18 years of age, a stable refraction for 12 months, an intraocular pressure of less than 21 mm Hg, and no history of autoimmune disease, diabetes, ocular surgery, or eye disease. In addition, patients had to cease wearing contact lenses for 2 weeks (rigid lenses) or 4 days (soft lenses) before the preoperative evaluation and before surgery. The disposable blade was used in the right eye first and then reused in the left eye.
  
  
  RESULTS
  The study evaluated 6242 eyes of 3121 patients with a mean age of 32.2 years ± 9.8 (SD). Group 1 comprised 2560 eyes (41%), and Group 2 comprised 3682 eyes (59%). The eyes in Group 1 had thinner flaps (P < .001). The right eyes had thicker flaps (P < .001). Flap thickness had a positive correlation with precutting central corneal thickness (CCT) and operating room humidity and a negative correlation with patient age, preoperative sphere and cylinder, and operating room temperature. Statistically significant differences were found in flap thickness between surgeons (P < .001). Larger suction rings created thicker flaps (P < .001). Stepwise regression models accounted for up to 28.1% of the variation in flap thickness.
  
  
  CONCLUSIONS
  Factors that were significantly correlated with flap thickness included the precutting CCT, whether the right or the left eye, the microkeratome head used, the surgeon performing the procedure, and the preoperative sphere. These findings might help prevent post-LASIK corneal ectasia.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors: From the Department of Ophthalmology (Mimouni, Levartovskyh, Kaiserman), Barzilai Medical Center, Ashkelon, and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, the Department of Ophthalmology (Nemet), Meir Medical Center, Kfar Sava and the Sackler School of Medicine, Tel-Aviv University, and Care-Vision Laser Centers (Sela, Munzer), Tel-Aviv, Israel. Electronic address: michael@intername.co.il.
authors: Michael
authors: M
authors: Mimouni
authors: From the Department of Ophthalmology (Mimouni, Levartovskyh, Kaiserman), Barzilai Medical Center, Ashkelon, and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, the Department of Ophthalmology (Nemet), Meir Medical Center, Kfar Sava and the Sackler School of Medicine, Tel-Aviv University, and Care-Vision Laser Centers (Sela, Munzer), Tel-Aviv, Israel.
authors: Arie Y
authors: AY
authors: Nemet
authors: From the Department of Ophthalmology (Mimouni, Levartovskyh, Kaiserman), Barzilai Medical Center, Ashkelon, and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, the Department of Ophthalmology (Nemet), Meir Medical Center, Kfar Sava and the Sackler School of Medicine, Tel-Aviv University, and Care-Vision Laser Centers (Sela, Munzer), Tel-Aviv, Israel.
authors: Shmuel
authors: S
authors: Levartovsky
authors: From the Department of Ophthalmology (Mimouni, Levartovskyh, Kaiserman), Barzilai Medical Center, Ashkelon, and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, the Department of Ophthalmology (Nemet), Meir Medical Center, Kfar Sava and the Sackler School of Medicine, Tel-Aviv University, and Care-Vision Laser Centers (Sela, Munzer), Tel-Aviv, Israel.
authors: Tzahi
authors: T
authors: Sela
authors: From the Department of Ophthalmology (Mimouni, Levartovskyh, Kaiserman), Barzilai Medical Center, Ashkelon, and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, the Department of Ophthalmology (Nemet), Meir Medical Center, Kfar Sava and the Sackler School of Medicine, Tel-Aviv University, and Care-Vision Laser Centers (Sela, Munzer), Tel-Aviv, Israel.
authors: Gur
authors: G
authors: Munzer
authors: From the Department of Ophthalmology (Mimouni, Levartovskyh, Kaiserman), Barzilai Medical Center, Ashkelon, and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, the Department of Ophthalmology (Nemet), Meir Medical Center, Kfar Sava and the Sackler School of Medicine, Tel-Aviv University, and Care-Vision Laser Centers (Sela, Munzer), Tel-Aviv, Israel.
authors: Igor
authors: I
authors: Kaiserman
mesh_terms: D000328:Adult; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000473:pathology*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery*; D012189:Retrospective Studies; D012307:Risk Factors; D013524:Surgical Flaps / Q000473:pathology*; D055815:Young Adult