Human hemoglobin denaturation as an alternative to the draize test for predicting eye irritancy of surfactants

Abstract

Purpose Quantification of eye irritancy has been a problem for both the consumer product industry and ophthalmic researchers because of the need to predict the toxic potential of preparations that may come into contact with the ocular surface. The Draize rabbit eye test has been used for 60 years in attempts to predict human ocular irritancy based on topical instillation of the potential irritant and subjective scoring of ocular inflammation by direct visualization of the rabbit eye. The inadequacies of the Draize test have led to efforts in several laboratories to develop alternatives. Methods We propose an alternative to the Draize eye irritation test, using human hemoglobin rather than bovine hemoglobin and studying the protein denaturation induced by potential irritants. Among the factors that affect eye irritation, protein denaturation has been reported as one of the most important factors that can result in corneal opacity. Human protein denaturation was measured as indicative of eye irritation. Results We studied different known irritant and non-irritant compounds to establish the predictability of the method. The compounds considered as irritants in vivo had the greatest effect in terms of decreased human hemoglobin absorbance. Conclusions The proposed method is able to easily differentiate between irritant and non-irritants products in an easy manner. The method is easy, rapid, economical, and provides enough information about the potential eye irritant action of different surfactants.