title: The impact of silicone hydrogel materials on overnight corneal swelling.
abstract: OBJECTIVE
  To identify the corneal swelling response associated with silicone hydrogel contact lens wear.
  
  
  METHODS
  Twenty-five subjects were recruited to participate in this single-center, controlled, single-masked, clinical trial. The corneal swelling response was evaluated by central corneal pachymetry after overnight wear of balafilcon A, etafilcon A, lotrafilcon A, senofilcon A, and no lens wear. More specifically, after 8 hours of closed-eye wear of each material, corneal thickness was measured immediately on eye opening, in addition to the first 4 hours of open-eye wear. Paired t tests were used to compare the swelling response from each condition to that associated with senofilcon A, and given the numerous statistical comparisons, a P value of <or=0.01 was considered significant.
  
  
  RESULTS
  At eye opening, there was no difference in the swelling response when comparing balafilcon A (1.35%), lotrafilcon A (1.22%), or no lens wear (0.77%) to senofilcon A (1.40%), although the swelling response associated with etafilcon A was significantly greater (P<0.001) than that associated with senofilcon A. There were no differences between balafilcon A, lotrafilcon A, and no lens wear compared to senofilcon A during the open-eye deswelling period. However, 1 hour after eye opening, corneal swelling remained significantly greater with etafilcon A than with senofilcon A (1.76% vs. -0.51%, respectively, P=0.01), although no other time-specific comparisons differed.
  
  
  CONCLUSIONS
  Silicone hydrogel lenses, with high oxygen transmissibilities, are associated with very little corneal swelling after overnight wear of the lenses.
authors.affiliation: Vistakon Johnson & Johnson Vision Care, Inc., Jacksonville, FL, USA. rsteffen@visus.jnj.com
authors.forename: Robert B
authors.initials: RB
authors.lastname: Steffen
authors.forename: Cristina M
authors.initials: CM
authors.lastname: Schnider
mesh_terms: D002940:Circadian Rhythm; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D015715:Corneal Edema / Q000209:etiology* / Q000473:pathology; D018592:Cross-Over Studies; D006801:Humans; D020100:Hydrogels / Q000009:adverse effects; D008689:Methacrylates / Q000009:adverse effects; D010100:Oxygen; D010539:Permeability; D012828:Silicones / Q000009:adverse effects; D016037:Single-Blind Method; D005466:Fluorocarbons
chemical_list: D020100:Hydrogels; D008689:Methacrylates; D010100:Oxygen; D012828:Silicones; C523195:balafilcon A; C114176:etafilcon; C481129:lotrafilcon A; D005466:Fluorocarbons; C523196:senofilcon A