title: Adaptive effects of 30-night wear of hyper-O(2) transmissible contact lenses on bacterial binding and corneal epithelium: a 1-year clinical trial.
abstract: OBJECTIVE
  To determine effects of lens type and oxygen transmissibility on human corneal epithelium during extended wear (EW).
  
  
  METHODS
  Prospective, randomized, double-masked, single-center, parallel treatment groups, 1-year clinical trial.
  
  
  METHODS
  One hundred seventy-eight patients completed the study: (1) high-O(2) soft lens (6-night [N] EW) (n = 27); (2) hyper-O(2) soft lens (6N-EW, n = 33) or (30N-EW, n = 66); and (3) hyper-O(2) rigid gas-permeable lens (RGP) (30N-EW, n = 52).
  
  
  METHODS
  Irrigation chamber to collect exfoliated corneal surface cells, confocal microscopy, and tear collection at baseline, 1, 3, 6, 9, 12 months of EW.
  
  
  METHODS
  (1) Pseudomonas aeruginosa (PA) binding to exfoliated corneal surface cells; (2) central epithelial thickness; (3) superficial epithelial cell area; (4) epithelial surface cell exfoliation; and (5) tear lactate dehydrogenase.
  
  
  RESULTS
  Quantitative evidence demonstrated increased binding of PA to human exfoliated corneal epithelial cells during the first 3 months of soft lens EW; the control high-O(2) test lens showed significantly higher bacterial binding (P < 0.05). Binding activity gradually decreased thereafter and returned to baseline after 9 and 12 months. The corneal epithelium demonstrated enlargement of surface cell size, thinning of central epithelium, and a significant decrease in surface cell shedding (P < 0.05). Remarkably, there was subsequent partial adaptive recovery in cell shedding and epithelial thickness but not surface cell size. There was no significant difference between 6N and 30N continuous wear of the hyper-O(2) soft lens for all outcome measures. Importantly, hyper-O(2) RGP lens wear did not show significantly increased PA binding during 1 year.
  
  
  CONCLUSIONS
  This study establishes three important new findings: (1) hyper-O(2) soft lens EW produces significantly less PA binding than the lower O(2) soft lens with no significant difference in PA binding with 6N versus 30N EW of the hyper-O(2) soft lens; (2) there is a remarkable adaptive recovery after 6 months with all soft lens wear with gradual return to prelens PA binding levels and partial recovery of other outcome measures for all test lenses EW except surface cell size; (3) 30N EW of the hyper-O(2) RGP lens produced no significant increases in PA binding over 1 year. Taken together, these results suggest that introduction of new hyper-O(2) transmissible lens materials into clinical use may offer safer EW, and future epidemiologic studies of ulcerative infectious keratitis should consider both lens type and time in lens EW in any incidence/risk analysis.
authors.affiliation: Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9057, USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Ren
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Ladage
authors.forename: Michael
authors.initials: M
authors.lastname: Molai
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: W Matthew
authors.initials: WM
authors.lastname: Petroll
authors.forename: James V
authors.initials: JV
authors.lastname: Jester
authors.forename: H Dwight
authors.initials: HD
authors.lastname: Cavanagh
mesh_terms: D000328:Adult; D001422:Bacterial Adhesion; D003262:Contact Lenses, Extended-Wear; D004311:Double-Blind Method; D019573:Epithelium, Corneal / Q000378:metabolism / Q000382:microbiology*; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D018613:Microscopy, Confocal; D010100:Oxygen / Q000378:metabolism*; D011446:Prospective Studies; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D013666:Tears / Q000201:enzymology; D013997:Time Factors
chemical_list: D007770:L-Lactate Dehydrogenase; D010100:Oxygen