title: The Ex Vivo Eye Irritation Test (EVEIT) in evaluation of artificial tears: Purite-preserved versus unpreserved eye drops.
abstract: OBJECTIVE
  Preservatives in artificial tears cause controversy. New developments such as the Purite system have been introduced into the market, with the promise of little damage to the corneal surface. We wanted to give insight into the differences in the effect of preserved and unpreserved artifical tears on rabbit corneas cultured with the Ex Vivo Eye Irritation Test (EVEIT) system.
  
  
  METHODS
  We compared the two artifical tears products Hylo Comod and Optive being dropped for 72 hours each hour one drop onto the corneal surface.
  
  
  METHODS
  Each cornea was mechanically wounded with four epithelial defects on each cornea with a size of 3 to 4.5 mm(2). With n = 4 corneas in the Hylo-Comod and n = 4 corneas in the Optive group, we exposed the corneal surfaces to repeated doses of these artificial tears for 3 days. We observed healing of corneal erosions and surface epithelial integrity with sodium-fluoresceine staining under cobalt blue light illumination.
  
  
  RESULTS
  We found nearly complete healing of epithelial defects with both artificial tears. The Hylo-Comod group healed significantly faster. After 72 hours, the vast majority of epithelial defects were closed. All corneas exposed to Purite showed superficial stippling, whereas the HyloComod group did not show any stippling of the cornea; this difference was significant.
  
  
  CONCLUSIONS
  Epithelial healing and recovery in the EVEIT system is observed in both groups, confirming the concept of artificial tears as a supporting factor of corneal health and healing. The superficial stippling of the corneal epithelium was observed only in the Optive group. This effect is considered as a marker of dry eye syndrome, and should be prevented by the application of artificial tears. Preservative-free eye drops such as HyloComod improve healing, and prevent symptoms of dry eye syndrome in the EVEITsystem. Compared to EVEIT results of former experiments with benzalconium chloride-preserved eye drops, Optive promoted healing of corneal erosions.
authors.affiliation: ACTO e.V. An-Institut der medizinischen Fakultät RWTH Aachen, Karlsburgweg 9, 52070 Aachen, Germany. schrage@acto.de
authors.forename: N
authors.initials: N
authors.lastname: Schrage
authors.forename: M
authors.initials: M
authors.lastname: Frentz
authors.forename: F
authors.initials: F
authors.lastname: Spoeler
mesh_terms: D000818:Animals; D003315:Cornea / Q000187:drug effects* / Q000378:metabolism; D065306:Corneal Injuries; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D015352:Dry Eye Syndromes / Q000517:prevention & control; D015590:Fluorophotometry; D007773:Lactates / Q000378:metabolism; D009883:Ophthalmic Solutions / Q000008:administration & dosage*; D009924:Organ Culture Techniques; D011310:Preservatives, Pharmaceutical / Q000008:administration & dosage*; D011817:Rabbits; D014945:Wound Healing / Q000187:drug effects*
chemical_list: D007773:Lactates; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical