title: Ocular surface health during 30-day continuous wear: rigid gas-permeable versus silicone hydrogel hyper-O2 transmitted contact lenses.
abstract: OBJECTIVE
  To determine the effects on corneal epithelial permeability and ocular response of 30 nights of continuous wear (CW) of gas permeable (GP) and silicone hydrogel (SiH) contact lenses.
  
  
  METHODS
  Ninety-one subjects successfully completed 30 days of CW of either GP (n = 42) or SiH (n = 49) contact lenses. Epithelial permeability (P(dc)) was measured by scanning fluorometer at an afternoon (PM) baseline session and again the next morning (AM). One randomly selected eye of each subject was patched overnight and the patch removed immediately before the AM visit. P(dc) measurements and ocular examinations were conducted at baseline and after 30 days of CW.
  
  
  RESULTS
  Epithelial permeability increased significantly after 30 days of CW in the patched eyes of the GP group (P = 0.022) and in the unpatched eyes of the SiH group (P = 0.004). The increase was driven primarily by the Asian subjects in each group (GP, P = 0.015; SiH, P = 0.001). There was no significant increase in either lens group in the non-Asian subjects. Multivariate models suggest that the change in AM P(dc) from baseline to 30 days of CW was also related to lens type (P = 0.035), time awake before measurement (P = 0.001), palpebral aperture size (P = 0.003), lens deposits (P = 0.020), and horizontal lens bearing (P = 0.003).
  
  
  CONCLUSIONS
  Subclinical increases in epithelial permeability can be caused by contact lens CW, despite the elimination of hypoxia. GP lenses permit recovery of the epithelium more quickly than do SiH lenses. Asians appear to be more susceptible to contact lens-induced epithelial changes than do non-Asians.
authors.affiliation: Clinical Research Center, School of Optometry, University of California, Berkeley, California 94720-2020, USA. mlin@berkeley.edu
authors.forename: Meng C
authors.initials: MC
authors.lastname: Lin
authors.forename: Thao N
authors.initials: TN
authors.lastname: Yeh
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Graham
authors.forename: Tan
authors.initials: T
authors.lastname: Truong
authors.forename: Carol
authors.initials: C
authors.lastname: Hsiao
authors.forename: Guan
authors.initials: G
authors.lastname: Wei
authors.forename: Audrey
authors.initials: A
authors.lastname: Louie
mesh_terms: D000293:Adolescent; D000328:Adult; D003262:Contact Lenses, Extended-Wear; D019573:Epithelium, Corneal / Q000378:metabolism*; D005006:Ethnicity; D015590:Fluorophotometry; D006801:Humans; D033401:Microscopy, Acoustic; D009216:Myopia / Q000503:physiopathology / Q000628:therapy; D010100:Oxygen / Q000378:metabolism*; D010539:Permeability; D012826:Silicone Elastomers; D013997:Time Factors; D055815:Young Adult
chemical_list: D012826:Silicone Elastomers; D010100:Oxygen