pH and H2O2 concentration of hydrogen peroxide disinfection systems

Hydrogen peroxide disinfection has caused discomfort for some soft contact lens wearers even though the solution was neutralized properly. The discomfort could be due to the endpoint pH of the system used or the residual H2O2 concentration. Using a digital pH meter and H2O2 concentration detection strips, we measured the pH and H2O2 concentration of seven different hydrogen peroxide disinfection systems over their recommended disinfection and neutralization cycles to determine their time courses and endpoint values. The final pH of the seven systems varied from 6.15 to 7.74 pH units. All systems resulted in residual H2O2 concentrations below threshold values. These findings indicated that the final pH may be the cause of patient discomfort after hydrogen peroxide disinfection and neutralization.