The EyeIRR-IS assay: Development and evaluation of an in vitro assay to measure the eye irritation sub-categorization of liquid chemicals

Abstract Several alternative methods have been developed and regulatory adopted by OECD as in vitro alternatives to the Draize eye irritation assay either to detect chemicals not requiring classification (No Category) or inducing serious damage to the eye (Category 1) but none are sensitive enough to identify chemicals inducing reversible eye effects (category 2) which are categorised by default. Therefore, the discriminatory power of a genomic approach applied to the SkinEthic™ Human Corneal Epithelium (HCE) model was investigated to allow subcategorization capacity according to UN GHS classification. An algorithm based on gene expression modulation on a training (62) and a test (31 liquids) chemical set, tested neat and at 30%was evaluated in an assay called EyeIRR-IS. Its accuracy prediction to distinguish Cat1/Cat2 from No Cat was 95% with a specificity of 89% and a sensitivity of 98%. For subcategorization into the 3 GHS classes the accuracy reached 84% with 94% Cat1, 67% Cat2 and 89% No Cat correctly predicted. No Cat.1 chemicals were underestimated as negative with a majority of misclassified Cat2 over predicted as Cat 1. In conclusion, the performance of the assay suggests its added value in a defined approach for liquids to replace the Draize assay.