Rabbit endothelial response to ophthalmic preservatives

The endothelial surface of isolated rabbit corneas were perfused for three hours with varying concentrations of benzalkonium chloride and cetylpyridinium chloride. The threshold for physiological and ultrastructural alteration of corneal endothelium is approximately 0.0001% for benzalkonium chloride and 0.01 mM for cetylpyridinium chloride. The effects of the surfactants can be induced with as little as a 15-minute exposure without subsequent recovery. Use of ophthalmic medications or irrigating solutions containing these agents inside the eye is potentially hazardous to the corneal endothelium. Topical administration of 0.133% benzalkonium chloride to the anterior surface of deepithelialized in vivo corneas (five doses, seven minutes apart) caused no alterations of corneal endothelial cell function or ultrastructure.