title: Effect of nitrogen flow on recovery of vision after excimer laser photorefractive keratectomy without nitrogen flow.
abstract: BACKGROUND
  Excimer laser (VISX) photorefractive keratectomy was performed using nitrogen flowing through the ocular fixation ring. It was felt that eliminating nitrogen flow may provide faster early visual rehabilitation.
  
  
  METHODS
  Two groups of 50 consecutive eyes underwent photorefractive keratectomy with (N2 flow) and without (no N2 flow) nitrogen flow, and were evaluated at 1 month postoperatively.
  
  
  RESULTS
  There were more under- or overcorrections exceeding 1.00 diopter (D) in the N2 flow than in the no N2 flow groups. Eighteen eyes in the N2 flow and 11 in no N2 flow groups saw 20/50 or less, without correction. Fourteen eyes in the N2 flow and nine eyes in the no N2 flow groups lost two or more lines of best spectacle-corrected visual acuity. Four eyes in the N2 flow and none in the no N2 flow groups increased more than 1.00 D of astigmatism.
  
  
  CONCLUSIONS
  The elimination of nitrogen flow in photorefractive keratectomy performed with the VISX laser appears to improve visual results in the early postoperative period.
authors.affiliation: Ophthalmology Research Laboratories, Cedars Sinai Medical Center, Los Angeles, CA 90048.
authors.forename: E
authors.initials: E
authors.lastname: Maguen
authors.forename: A B
authors.initials: AB
authors.lastname: Nesburn
authors.forename: T
authors.initials: T
authors.lastname: Papaioannou
authors.forename: J J
authors.initials: JJ
authors.lastname: Salz
authors.forename: J I
authors.initials: JI
authors.lastname: Macy
authors.forename: C
authors.initials: C
authors.lastname: Warren
mesh_terms: D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000209:etiology; D003315:Cornea / Q000502:physiology / Q000601:surgery*; D005260:Female; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D009584:Nitrogen / Q000009:adverse effects; D012189:Retrospective Studies; D014785:Vision, Ocular / Q000502:physiology*; D014792:Visual Acuity
chemical_list: D009584:Nitrogen