Histopathological evaluation of the ocular-irritation potential of shampoos, make-up removers and cleansing foams in the bovine corneal opacity and permeability assay

The bovine corneal opacity and permeability (BCOP) assay is an alternative method to the in vivo Draize eye test in rabbits for evaluating eye irritation in vitro. Here, we compared the numerical results of the BCOP assay with the corresponding histopathology for three different corneas for each test substance, including commercially available shampoos, make-up removers and cleansing foams that contained surfactants and other ingredients. The histopathological score was defined based on the severity of lesions in the corneal epithelium. The histopathological findings and scores of the three sections for each test substance were comparable. The in vitro irritancy score (IVIS) generally corresponds to the corneal irritant potential of the test substances assigned on the basis of the histopathological findings in this study. In the present study, we characterized the histopathology of the corneal epithelium and stroma and especially showed that the corneal epithelial injury caused by test substances might be important in assessment of test substances that are mild eye irritants (category 2B) as classified by the United Nations (UN) Globally Harmonized System of Classification and Labelling of Chemicals (GHS), as corneal lesions suggestive of classification into category 2B were localized on the border between the corneal epithelium and stroma, which contained cell elements related to assessment of prognosis of an in vivo eye injury. Histopathological assessment might be useful in predicting in vivo ocular irritation, particularly for test substances with an IVIS >3.1 but ≤25 that are classified as mild irritants (category 2B) according to the UN GHS.