THE EPIOCULAR PREDICTION MODEL: A REPRODUCIBLE IN VITRO MEANS OF ASSESSING OCULAR IRRITANCY POTENTIAL.

The EpiOcular™ tissue model (OCL-200) is an organotypic model of the human corneal epithelium (HCE) cultured from normal human keratinocytes using serum-free medium. Haematoxylin and Eosin stained histological sections show the structure of EpiOcular to closely parallel that of the HCE. During 1998, 85 lots of OCL-200 were produced and monitored using the MTT assay. The common surfactant, Triton X-100 (0.3%), was used as a positive control and the Effective Time-50 values (time of exposure after which viability is reduced to 50% [ET50]) were determined for each lot of tissue. The 1998 ET50 average of 25.2 ± 5.6 minutes (± 1 standard deviation) was not significantly different (p > 0.75) than the 1996 average of 24.9 ± 6.3 minutes (n = 47 lots), the first year of commercial production. ET50 values were measured for 19 water-soluble chemicals from the ECETOC database and 41 cosmetic or personal care products/ingredients. Draize data for these materials were correlated to ET50 values and a prediction model was constructed: Draize = -4.74 + 101.7/ (ET50) ^ 0.5 (correlation coefficient, r = 0.90). Stability of the EpiOcular model for international shipment was probed by shipping the tissue to ZEBET in Germany. A plot of the predicted Draize in the two laboratories gave r = 0.94; plotting predicted versus actual Draize scores gave r = 0.90 and r = 0.94, for MatTek and ZEBET, respectively. Thus, the EpiOcular tissue model is reproducible and appears to be an in vitro means of accurately predicting in vivo ocular irritancy.

Draize, EpiOcular, Eye irritation, Ocular irritancy testing, Ocular irritation, Ocular irritation testing, Reproducibility, Reproducible