6. In vitro" eye irritation or corrosion tests

In order to limit the number of animals tested and animal suffering, "in vitro" tests on isolated organs have been developed.

OECD Test No. 492B: reconstituted human cornea test. The test uses a reconstructed epithelium similar to the human cornea, which closely mimics the histological, morphological, biochemical and physiological properties of the human organism. It is based on the assessment of cytotoxicity following exposure to a substance after two incubation times. Cytotoxicity is expressed as a decrease in the mitochondrial conversion of MTT (thiazolyl blue tetrazolium bromide) to another colored component, formazan. MTT is used to measure cellular metabolic activity, indicative of cell viability, proliferation and toxicity. Viable cells contain NAD(P)H-dependent oxidoreductases that reduce MTT to formazan.

This colorimetric assay...