An interlaboratory assessment of the Eytex system

Seventeen raw materials and chemical formulations were evaluated in the Eytex System to determine the ability of this assay in vitro to predict eye irritation potential in vivo. All the test samples, which represented a wide range of chemical types and eye irritancy potential in vivo, were provided by one of the participating laboratories. Historical data from tests in vivo were available for each of the test samples, so testing in vivo specifically for this study was not necessary. Samples were evaluated by both the membrane partition assay (MPA) and the rapid membrane assay (RMA). The sensitivity, specificity, predictivity and equivalence of the Eytex assay were determined by comparison with the rabbit eye irritation data, using each of the different Eytex Draize Equivalent (EDE) classification schemes. Regardless of the classification scheme used, the correlation between the scores in vivo and in vitro was poor. The Eytex System consistently overclassified materials of low irritancy in vivo and underclassified those test materials of moderate irritancy or above. On the basis of the results from the 17 materials tested in this study, the Eytex System appears unsuitable as a replacement in vitro for ocular irritancy testing of all types of chemical. However, Eytex may have a place as a pre-screening method used as part of a test battery.