Evaluation of an agarose overlay assay to determine the eye irritation potential of detergent-based products

The in vitro agarose overlay method (using L929 mouse fibroblast cells) has been evaluated and modified as an in vitro alternative to the Draize test for the ranking of ocular irritancy of detergent-based products. Modifications examined include the use of shorter incubation times, dilution of test materials and use of thiazolyl blue reduction as an alternative endpoint. Several cationic and anionic detergent-based products have been tested and ranked in order of their toxicity in this assay. Good correlations were found between these ranks and the appropriate in vivo ranks for irritancy. Thus an in vitro agarose overlay assay may be useful as a screening assay in irritancy prediction. The advantages of the agarose-overlay method over other similar in vitro tests include speed, lower cost, simple equipment and the ability to test formulations as well as pure substances.