The Changes of Ultrastructure and Function of the Corneal Endothelial Cell Caused by Benzalkonium Chloride

ABSTRACT

The purpose of this study was to evaluate alterations in corneal endothelial cell function and ultrastructure caused by benzalkonium chloride (BAC). Sixteen albino rabbits (32 eyes)were used for this study. One cornea of each matched pair was assigned to experimental group and the other cornea to control group. The experimental groups were divided into 4 groups, of which corneal endothelium were perfused with 0.01%, 0.001%, 0.0002%, and 0.0001% BAC. After paired rabbit corneas were isolated and mounted in the in vitro dual-chambered specular microscope, experimental corneas of each matched pair were perfused with different concentrations of BAC. Control corneas were perfused with glutathione-bicarbonate-Ringer solution(GBR). Corneal thickness was measured every 15 minutes throughout the perfusion period.Swelling rates were calculated by linear regression analysis, and compared to swelling rate of each paired mate perfused with GBR alone. At the end of perfusion,the corneas were fixed in 2.5%glutaraldehyde solution for transmission electron microscopy(TEM). Swelling rates of rabbit corneas perfused with BAC, 0.0001% did not differ significantly from control corneas (p>0.05). But, 0.0002%, 0.001%, and 0.01% BAC differed significantly from control corneas (p<0.05). BAC, 0.0001% showed normal corneal endothelial findings, but 0.0002% and 0.001% BAC showed reversible endothelial cellular injury. BAC, 0.01% showed irreversible endothelial cellular injury such as loss of nuclear membrane and disruption of cellular organelles. The results of this study indicate that long-term use of topical eye solutions containing BAC might induce corneal endothelial damage, especially in the absence of epithelial barrier such as corneal ulcer.