title: Impact of rigid gas-permeable contact lens extended wear on corneal epithelial barrier function.
abstract: OBJECTIVE
  To measure the effect of hypoxia and eye closure on epithelial permeability to fluorescein (P(dc)) during rigid lens extended wear (EW).
  
  
  METHODS
  Central corneal thickness (CT) and P(dc) were measured in 42 subjects with an optical pachometer and automated scanning fluorophotometer, respectively. All subjects had been successfully wearing rigid gas-permeable (RGP) lenses on a 6-night EW regimen, and each individual was randomized to wear either medium- or high-oxygen-permeable (Dk) RGP lenses (two types of siloxane-fluorocarbon polymer lenses with Dk of 49 and 92). CT and P(dc) measurements were performed at an afternoon visit (baseline) and were repeated in the morning after 8 hours of overnight wear. Subjects slept with a patch over the right eye. The patch was not removed until immediately before the morning measurement.
  
  
  RESULTS
  The mean overnight swelling response for subjects in the medium-Dk group was greater than that in the high-Dk group. Results of a paired t-test indicate that the eye wearing the medium-Dk lens with a patch overnight had a significant increase in epithelial permeability. Results of mixed-effect models suggest that eye closure and lens-induced hypoxia are significant factors in altering P(dc).
  
  
  CONCLUSIONS
  The results indicate that corneal epithelial permeability increases with hypoxic dose and that epithelial barrier function is impaired by overnight rigid lens wear.
authors.affiliation: School of Optometry, University of California, Berkeley, California 94720-2020, USA. mlin@spectacle.berkeley.edu
authors.forename: Meng C
authors.initials: MC
authors.lastname: Lin
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Graham
authors.forename: Robert E
authors.initials: RE
authors.lastname: Fusaro
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Polse
mesh_terms: D000328:Adult; D001692:Biological Transport / Q000502:physiology; D003262:Contact Lenses, Extended-Wear; D019573:Epithelium, Corneal / Q000378:metabolism* / Q000503:physiopathology; D005143:Eyelids / Q000502:physiology; D005260:Female; D019793:Fluorescein / Q000378:metabolism; D015590:Fluorophotometry; D006801:Humans; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D010539:Permeability; D012683:Sensory Deprivation
chemical_list: D019793:Fluorescein