The eye is an extremely important organ since it is considered that 80% of information received by humans comes from vision. Eye irritation test, which evaluates the effects of accidental contact with cosmetics as well as fabric and home care products in the eyes, is indispensable for assessment to provide safe and secure products to customers. Since 2000, Kao has been developing the "Short Time Exposure (STE)" test, an original in vitro eye irritation test using cultured corneal cells. The "STE" test has been peer-reviewed and is now listed as Test Guideline (TG 491) in the Organization for Economic Co-operation and Development (OECD). Although it is currently widely used in Japan and other countries, there are limitations to completely understand complex biological responses with a single in vitro test.
Eye irritation starts when a substance comes into contact with the eye, which quickly affects corneal epithelial cells. When the effect to the epithelial cells is severe, the substance can penetrate and damage corneal keratocytes. To focus on the biological responses occurred during eye irritation, Kao has developed a novel approach with a combination of the following two tests: the "STE" test and the "Bovine Corneal Opacity and Permeability" test (OECD TG 437). The former is highly accurate in assessing non eye irritant, whereas the latter can assess severe eye irritant precisely. Currently, in order to disseminate this approach worldwide, Kao is working with Cosmetics Europe to be adopted as OECD guidelines. We believe that these efforts regarding the development of "STE" are important to provide an alternative approach for eye irritation and reduce animal experiments not only by Kao but also throughout the world.