A report card on hydrogen peroxide for contact lens disinfection.

Hydrogen peroxide (H2O2) is one of the best disinfectants for contact lenses. Despite the fact that hydrogen peroxide challenges microorganisms of all kinds, issues such as time of exposure, post-neutralization residuals, and lens stability remain. Data indicate that the currently recommended short exposure time (10 to 15 minutes) in inadequate for protection against fungi and Acanthamoeba and that at least 2 hours is necessary. The addition of weekly enzyme for lens cleaning is also essential in decreasing the incidence of contact lens-related conjunctivitis when lenses are not replaced frequently. In studies at the Cornea and Contact Lens Research Unit (CCLRU) of the University of New South Wales, daily wear of "disposable" lenses, mechanical cleaning, an H2O2 system, and lens disposal on a monthly basis resulted in an adverse response rate of almost zero over the first year of use. Residual H2O2 levels are of concern with some systems. Although data indicate that 100 ppm of H2O2 is the threshold for ocular awareness in many individuals, post-neutralization pH at the end of the neutralization cycle plays an important role in the occurrence of residual effects. Lens material composition also may play a role in determining the rate and degree of post-neutralization parameter recovery. These issues underscore the need for continued clinical research of H2O2 to update our understanding of the best methods of use for this valuable disinfection regimen.