Prediction of eye irritation potential of surfactant-based rinse-off personal care formulations by the bovine corneal opacity and permeability (BCOP) assay.

Abstract

Evaluation of eye irritation potential is a routine part of product safety testing. Many companies have elected to use in vitro methods for this evaluation. We used the bovine corneal opacity and permeability (BCOP) assay for the prediction of the eye irritation potential of surfactant-based rinse-off personal care formulations in this study because of its positive performance in previous studies (1), and its potential to measure depth of injury through histological evaluation. The BCOP uses isolated corneas maintained in short-term organ culture and measures changes in opacity and epithelial barrier integrity (as determined by fluorescein passage through the cornea). Surfactants (anionic and nonionic) used in personal care formulations induce only small increases in direct opacity but the degree of epithelial damage is reflected in permeability measurement (OD490). The permeability measurement is the primary endpoint for this class of products. Marketed liquid hand soap was selected as the benchmark due to extensive in vivo and market history data. Using the liquid hand soap, a 25% v/v aqueous dilution with a 30-minute exposure produced the optimal resolution. A series of products with known in vivo eye irritation scores were evaluated to establish a prediction model. Histological evaluation was used to compare the degree of tissue damage to the permeability scores. Based on the permeability scores and histological review, the testing protocol for a surfactant-based rinse-off personal care formulation was developed using a 25% v/v aqueous dilution, a 30-minute exposure, concurrent testing of the benchmark control, and use of permeability measurements as the endpoint for the evaluation of eye irritation potential.