OCULAR IRRITATION - PATHOLOGICAL-CHANGES OCCURRING IN THE RAT WITH SURFACTANTS OF UNKNOWN IRRITANCY

We believe the development and validation of in vitro alternatives to eliminate the need to use animals in ocular irritation testing must be based on a thorough understanding of the mechanisms of ocular irritat ion. We have recently undertaken the task of developing such an unders tanding for a panel of surfactants. The purpose of this study was to e xpand our current panel of surfactants for which the microscopic chang es occurring over time have been characterized. Macroscopic and micros copic findings regarding the ocular irritation of 6 surfactants of rel atively unknown irritancy were compared to those of 6 surfactants of k nown irritancy. The right eye of each rat was treated by placing 10 mu l of a surfactant directly on the cornea. Untreated left eyes served as the controls. At 3 hr and on days 1, 3, and 35, eyes and eyelids we re collected for microscopic examination. Collectively, the macroscopi c and microscopic findings revealed 3 surfactants to be similar to the mildly irritating surfactants previously studied, and 3 surfactants t o be similar to the moderately irritating surfactant previously studie d. Information such as this will be important to develop mechanistical ly based in vitro alternatives to replace the use of animals for ocula r irritation testing.