title: Impact of silicone hydrogel lenses and solutions on corneal epithelial permeability.
abstract: OBJECTIVE
  The primary purpose of this pilot study was to compare epithelial barrier function (EBF) and staining in a small group of participants using a silicone hydrogel (SH) lens worn on a daily basis with two different care regimens. Secondarily, the aim was to see if there was any correlation between corneal staining and EBF.
  
  
  METHODS
  The corneal EBF of 10 non-lens wearers (control) and 15 age-matched asymptomatic SH contact lens wearers (test) were assessed using fluorophotometry. Biomicroscopy was performed to assess corneal staining after the EBF was measured. The lens wearers wore PureVision (FDA group V) SH lenses for two consecutive 1-month periods while using either Alcon Opti-Free Express or Renu Fresh using a randomized, investigator-masked, crossover design. Control subjects were assessed on one occasion, and lens wearers were examined before fitting with lenses and after 7, 14, and 28 days of lens wear, with each combination.
  
  
  RESULTS
  Compared with the control group, both study groups had an increase in epithelial permeability at baseline (p ≤ 0.04). There were no changes in EBF during the treatment period for either solution (p = 0.87). A significant difference in EBF was found between the test groups during the treatment period (p = 0.02), with greater permeability in the Renu Fresh-disinfected lenses. There was poor correlation between corneal staining and EBF (r = 0.35, p > 0.05) because of large individual variations.
  
  
  CONCLUSIONS
  Daily wear of highly oxygen-permeable SH lenses increases corneal epithelial permeability to fluorescein probably because of increased mechanical effects. In addition, certain lens-solution interactions can add to this effect, as seen in this study. Despite having a low amount of central corneal staining in the Renu Fresh group, staining and EBF did not prove to be well correlated. The presence of central corneal staining is a confounding factor when measuring EBF.
authors: Centre for Contact Lens Research, School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
authors: Stephanie
authors: S
authors: Duench
authors: Luigina
authors: L
authors: Sorbara
authors: Nancy
authors: N
authors: Keir
authors: Trefford
authors: T
authors: Simpson
authors: Lyndon
authors: L
authors: Jones
mesh_terms: D000328:Adult; D002463:Cell Membrane Permeability / Q000502:physiology*; D018639:Contact Lens Solutions; D003263:Contact Lenses, Hydrophilic; D018592:Cross-Over Studies; D004311:Double-Blind Method; D019573:Epithelium, Corneal / Q000378:metabolism*; D005260:Female; D019793:Fluorescein / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism*; D015590:Fluorophotometry; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008297:Male; D010865:Pilot Projects; D012826:Silicone Elastomers; D055815:Young Adult
chemical_list: D018639:Contact Lens Solutions; D005456:Fluorescent Dyes; D012826:Silicone Elastomers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D019793:Fluorescein