Effect of hydrogen peroxide on epithelial light-scattering and stromal deturgescence

The anterior epithelium of the cornea is particularly sensitive to toxic solutions. A zone of increased light-scattering in the anterior epithelium, the anterior bright band (ABB), increases in thickness when exposed to toxic substances, but is not affected by benign solutions. With some solutions the thickness of the stroma also increases. The endothelial surfaces of rabbit corneas were perfused in vitro at 35 degrees C with various solutions, and the ABB and stromal thickness determined by specular microscopy. With glutathione-bicarbonate Ringer as control, the epithelium was bathed with concentrations of hydrogen peroxide (H2O2) at 72, 153, and 235 ppm with either a 10-minute pulse dose or a sustained dose of 150 minutes. In the 10-minute pulse-dose experiment, the H2O2 concentrations caused no significant changes in the ABB or stroma when compared with the control. In the 150-minute sustained-dose experiment, significant changes in both the ABB and stroma thickness were noted at the 153 and 235 ppm concentrations, but the 72 ppm dose caused no significant change. Exposure to benzalkonium chloride for 150 minutes produces a greater increase in both ABB and stromal thickness than does exposure to 235 ppm hydrogen peroxide.