The Ex Vivo Eye Irritation Test (EVEIT) in evaluation of artificial tears: Purite®-preserved versus unpreserved eye drops
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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.
We compared the two artifical tears products Hylo Comod® and Optive® being dropped for 72 hours each hour one drop onto the corneal surface.
Each cornea was mechanically wounded with four epithelial defects on each cornea with a size of 3 to 4.5 mm2. 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.
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.
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.
KeywordsEVEIT Cornea Healing Preservative free medication Dry eye syndrome Purite® Hyaluronic acid