title: The effects of one-hour wear of high-Dk soft contact lenses on corneal pH and epithelial permeability.
abstract: OBJECTIVE
  Previous studies have shown that 1-hour closed-eye contact lens wear with a low-Dk lens causes a significant reduction in corneal pH and an increase in epithelial permeability. In the present study, we evaluated the effects of super-high-Dk/t soft lenses on corneal epithelial barrier function and stromal pH.
  
  
  METHODS
  Corneal thickness was measured by optical pachometry, while epithelial permeability and stromal pH were measured by fluorophotometry. A paired-eye design was used in which one eye was randomly allocated to wear a high-oxygen-permeable soft lens (CIBAVision Focus/NIGHT & DAY (Dk/t= 175) while the other eye did not wear a lens.
  
  
  RESULTS
  After 1-hour closed-eye lens wear, neither the difference in corneal swelling (P = 0.206) nor the permeability (P = 0.055) between both eyes was significantly different. The mean pH values under open-eye conditions were 7.66 vs. 7.57 for the treatment and control eyes, respectively (P = 0.082), dropping to 7.27 vs. 7.25 after 1-hour eye closure (P = 0.283).
  
  
  CONCLUSIONS
  Although our results are limited to a 1-hour observation period, they do provide evidence that high-Dk materials may eliminate corneal acidosis and reduced epithelial barrier function that accompany closed-eye contact lens wear with lower-Dk soft lens materials.
authors.affiliation: Morton D. Sarver Laboratory for Cornea and Contact Lens Research, School of Optometry, University of California, Berkeley 94720-2020, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Lin
authors.forename: A D
authors.initials: AD
authors.lastname: Graham
authors.forename: K A
authors.initials: KA
authors.lastname: Polse
authors.forename: N A
authors.initials: NA
authors.lastname: McNamara
authors.forename: T G
authors.initials: TG
authors.lastname: Tieu
mesh_terms: D000293:Adolescent; D000328:Adult; D003263:Contact Lenses, Hydrophilic; D003287:Contrast Media / Q000378:metabolism; D003319:Corneal Stroma / Q000502:physiology*; D019573:Epithelium, Corneal / Q000378:metabolism*; D019793:Fluorescein / Q000378:metabolism; D015590:Fluorophotometry; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D006863:Hydrogen-Ion Concentration; D009883:Ophthalmic Solutions; D010100:Oxygen / Q000378:metabolism*; D010539:Permeability; D013997:Time Factors
chemical_list: D003287:Contrast Media; D009883:Ophthalmic Solutions; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D010100:Oxygen; D019793:Fluorescein