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M. Goss, N. F. Schrage, F. Markus; Is the Ex Vivo Eye Irritation Test (eveit) Able to Detect Toxicity of Preservatives in Eye Drops? Hazard Evaluation on the Eye Using Repeated Exposure and Observing Possible Damage. Invest. Ophthalmol. Vis. Sci. 2007;48(13):806.
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© ARVO (1962-2015); The Authors (2016-present)
For more than 60 years the Draize-Test has been used as an animal experiment using live rabbits to assess the potential of chemical substances to cause human ocular irritation after chemical exposure. We aim to replace the Draize test and to improve preclinical testing of drugs and chemical substances being in direct contact to the cornea. Prognosis of potentially occurring side effects is a key issue of the REACH initiative and all preclinical testing in drugs, chemicals and cosmetics. Especially the multiple exposures and the time dependent effect of exposures on the eye are an unsolved problem of other test systems, such as cell culture techniques and the corneal bovine opacity test.
The Ex vivo eye irritations Test (EVEIT) is a self healing system with living corneas obtained from abattoir rabbit eyes, which are cultured in special perfusion chambers. These corneas are exposed to a mechanical abrasion and repeated exposures to test substances dropped on the centre of the cornea. The exposures were done with citrate hyaluronate eye drops, hyaluronate eye drops containing various amounts of Benzalconiumchloride (BAC), 0.025 to 0.5%, and culture medium (MEM) as control.
In earlier works using the EVEIT we found perfect epithelial healing after mechanical abrasions but not after testing irritants because we obviously exceeded the capacities of recovery by overdosing. Nevertheless the corneas reacted in a dose dependent manner by morphological damage, release of mediators like IL8 and VEGF. Furthermore we observed endothelial necrosis in higher doses of corrosives. Later on we used phosphate hyaluronate eye drops in repeated exposures and found corneal calcifications whereas no detectable calcification occurred, using citrate hyaluronate. In this study we found a dose dependent inhibition of epithelial recovery and damage of the metabolic turnover of the cornea in glucose consumption/lactate production in the testing with different concentrations of BAC in the citrate hyaluronate eye drops, whereas complete epithelial healing in the corneas treated with MEM and hyaluronate containing eye drops only could be detected.
This new test system with incubated corneas is able to detect wound healing after mechanical and/or chemical damage to the corneas. With morphological and metabolical examinations wound healing can be detected and eveluated. This is a good alternative to any animal experiments further more it offers better conditions to evaluate the grade of damage done to the corneas.
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