title: The effect of procedure room temperature and humidity on LASIK outcomes.
abstract: OBJECTIVE
  To determine whether procedure room temperature or humidity during LASIK affect refractive outcomes in a large patient sample.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  A total of 202 394 eyes of 105 712 patients aged 18 to 75 years who underwent LASIK at an Optical Express, Inc., location in their United Kingdom and Ireland centers from January 1, 2008, to June 30, 2011, who met inclusion criteria.
  
  
  METHODS
  Patient age, gender, flap creation technique, pre- and 1-month post-LASIK manifest refraction, and ambient temperature and humidity during LASIK were recorded. Effect size determination and univariate and multivariate analyses were performed to characterize the relationships between LASIK procedure room temperature and humidity and postoperative refractive outcome.
  
  
  METHODS
  One month post-LASIK manifest refraction.
  
  
  RESULTS
  No clinically significant effect of procedure room temperature or humidity was found on LASIK refractive outcomes. When considering all eyes in our population, an increase of 1°C during LASIK was associated with a 0.003 diopter (D) more hyperopic refraction 1 month postoperatively, and an increase in 1% humidity was associated with a 0.0004 more myopic refraction. These effect sizes were the same or similar when considering only myopic eyes, only hyperopic eyes, and subgroups of eyes stratified by age and preoperative refractive error.
  
  
  CONCLUSIONS
  Neither procedure room temperature nor humidity during LASIK were found to have a clinically significant relationship with postoperative manifest refraction in our population.
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, California. Electronic address: mseider@gmail.com.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Seider
authors.forename: Stephen D
authors.initials: SD
authors.lastname: McLeod
authors.forename: Travis C
authors.initials: TC
authors.lastname: Porco
authors.forename: Steven C
authors.initials: SC
authors.lastname: Schallhorn
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D006813:Humidity; D006956:Hyperopia / Q000503:physiopathology / Q000601:surgery*; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D009873:Operating Rooms; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D013524:Surgical Flaps; D013696:Temperature; D016896:Treatment Outcome; D055815:Young Adult