Abstract
Recently, safety evaluation tests that do not involve animal experiments have been prosperously developing. However, the optimal evaluation materials and methods for assessing ocular irritancy have not been well investigated. In this study, we determined the optimal evaluation method for testing ocular irritation using a human cultured corneal epithelium model (corneal model). In order to assess adequate treatment conditions for the corneal model, we used cetylpyridinium chloride (CPC), which has been recognized as an irritant chemical by the Draize eye test. The irritancy elicited by multiple concentrations of CPC was evaluated by a cytotoxicity assay under nine treatment conditions and compared to the Draize score. The treatment conditions that included a 5-second exposure period followed by a 24-hour post-incubation period (hereafter called protocol "5-sec+24-h") showed a significant correlation between cytotoxicity and the Draize score. Furthermore, the dose-dependent cytotoxicity of six test chemicals was assessed by protocol "5-sec+24-h" and found to correlate with the Draize eye test results.
