title: Short term wear of high Dk soft contact lenses does not alter corneal epithelial cell size or viability.
abstract: OBJECTIVE
  Current contact lenses (CLs) when worn on an extended wear basis cause corneal epithelial alterations. The aim of this study was to evaluate changes in corneal epithelial cell morphology and physiology following short term (3 months) wear of highly oxygen permeable CLs and to compare this with disposable CLs.
  
  
  METHODS
  Subjects were wearers of highly oxygen permeable CLs (n=11, wearing CLs on a 30 night schedule), disposable CL users (n=6, wearing CLs on a 6 night schedule), and non-CL wearers (n=20). Mean CL wear experience was 3 months. Epithelial cells were harvested using corneal cytology and were stained using acridine orange and ethidium bromide. Epithelial cell size and viability were determined.
  
  
  RESULTS
  The majority of epithelial cells recovered were non-viable (71%), and the mean longest cell diameter was 38 (SD 8) microm. Disposable CLs caused an increase in cell size (42 (7) microm) compared with both non-wear (39 (7) microm, p=0.01) and wear of highly oxygen permeable CLs (37 (10) microm, p=0.0049). There was no difference in cell viability between groups.
  
  
  CONCLUSIONS
  Extended wear of disposable CLs caused an 8% increase in cell diameter in harvested corneal epithelial cells following 3 months of CL wear. Cells harvested following 3 months' wear of highly oxygen permeable CLs were indistinguishable from those recovered from non-CL wearers.
authors.affiliation: Cornea and Contact Lens Research Unit, School of Optometry, the University of New South Wales, Sydney, New South Wales, Australia. F.Stapleton@cclru.unsw.edu.au
authors.forename: F
authors.initials: F
authors.lastname: Stapleton
authors.forename: S
authors.initials: S
authors.lastname: Kasses
authors.forename: S
authors.initials: S
authors.lastname: Bolis
authors.forename: L
authors.initials: L
authors.lastname: Keay
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D048429:Cell Size; D002470:Cell Survival; D003262:Contact Lenses, Extended-Wear; D003263:Contact Lenses, Hydrophilic; D004209:Disposable Equipment; D019573:Epithelium, Corneal / Q000166:cytology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000737:chemistry; D010539:Permeability; D013048:Specimen Handling / Q000379:methods; D013997:Time Factors
chemical_list: D010100:Oxygen