Chorioallantoic membrane assays (HET-CAM and CAM-TBS): alternative tests for performing toxicological evaluation of products with low potential for ocular irritation

Abstract

This study aimed at evaluating the predictive potential of the conventional Hen’s Egg Chorionallantoic Membrane (HET-CAM) test and its version CAM-TBS, that quantifies the damage to the membrane cause by absorption of dye trypan blue, in order to propose an alternative assay for assessing the ocular toxicity. Twenty collyria were evaluated in vivo by means of Draize eye irritation test, and by in vitro HET-CAM and CAM-TBS assays. All the analyzed collyria were classified as non-irritant by in vivo testing. In HET-CAM assay, 4 false positive results were observed, and the test specificity and accuracy were of 80%. CAM-TBS showed a better performance, having specificity and accuracy of 100%. The cut-off set up for HET-CAM test (0.9) is discussed, as the false-positive results observed in this study could have been bypassed if the category “non-irritant” encompassed “non-irritant” and “mild irritant” products, in compliance with the criteria recommended for CAM-TBS (cut-off = 7.0).