title: Comparison of the effects of ophthalmic solutions on human corneal epithelial cells using fluorescent dyes.
abstract: OBJECTIVE
  To investigate the effect of differently preserved ophthalmic solutions on the viability and barrier function of human corneal epithelial cells (HCEC) using fluorescent dyes.
  
  
  METHODS
  HCEC monolayers were exposed to the ophthalmic solutions containing benzalkonium chloride (BAK), edetate disodium, polyquad, stabilized oxychloro complex (Purite), sodium perborate, or sorbic acid for 5 min, 15 min, and 1 h. At 24 h after exposure, the cultures were assessed for metabolic activity using alamarBlue. The enzyme activity, membrane integrity, and apoptosis were evaluated using confocal microscopy. Barrier function was assessed using sodium fluorescein.
  
  
  RESULTS
  The metabolic assay showed that the BAK-preserved ophthalmic solutions significantly reduced cell viability after a 5-min exposure compared to the phosphate buffered saline treated control (P<0.05). Using confocal microscopy, the micrographs showed that BAK caused a reduction in the enzyme activity, increased membrane permeability, and decreased the number of viable cells. Ophthalmic solutions with new preservatives had varying time-dependent adverse effects on cell viability, and the preservative-free solution had the least effect on HCEC. Sodium fluorescein permeability showed that HCEC monolayers treated with BAK-preserved solutions were more permeable to sodium fluorescein than those treated by the other ophthalmic solutions (P<0.05).
  
  
  CONCLUSIONS
  BAK-preserved solutions had greater adverse effects on metabolic activity, enzyme activity, membrane integrity, cell viability, and barrier function than the solutions that were not preserved with BAK. Our study suggests that BAK-free especially, preservative-free ophthalmic solutions are safer alternatives to BAK-preserved ones.
authors.affiliation: 1 School of Optometry and Vision Science, University of Waterloo , Waterloo, Ontario, Canada .
authors.forename: Manlong
authors.initials: M
authors.lastname: Xu
authors.forename: Jacob G
authors.initials: JG
authors.lastname: Sivak
authors.forename: David J
authors.initials: DJ
authors.lastname: McCanna
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D019573:Epithelium, Corneal / Q000166:cytology / Q000378:metabolism*; D019793:Fluorescein / Q000008:administration & dosage / Q000493:pharmacokinetics; D005456:Fluorescent Dyes / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006801:Humans; D018613:Microscopy, Confocal; D009883:Ophthalmic Solutions; D010078:Oxazines / Q000008:administration & dosage* / Q000493:pharmacokinetics; D010539:Permeability; D011310:Preservatives, Pharmaceutical / Q000737:chemistry / Q000633:toxicity*; D013997:Time Factors; D014966:Xanthenes / Q000008:administration & dosage* / Q000493:pharmacokinetics
chemical_list: D005456:Fluorescent Dyes; D009883:Ophthalmic Solutions; D010078:Oxazines; D011310:Preservatives, Pharmaceutical; D014966:Xanthenes; C005843:resazurin; D019793:Fluorescein