Contact Lens Case Reports
Comparing Peroxide Systems
By Patrick J. Caroline, FAAO, & Mark P. André, FAAO
We both have been strong advocates of hydrogen peroxide contact lens disinfection since we entered this industry some 35 years ago. Even today, you could write volumes on the many advantages of peroxide over multipurpose disinfection systems; however, multipurpose systems continue to dominate our industry.
Current H2O2 Systems
Currently, there are three FDA-approved hydrogen peroxide systems marketed in the United States: Clear Care (Ciba Vision), Oxysept Ultracare Formula (Abbott Medical Optics [AMO]), and One Step (Sauflon Pharmaceuticals). All of these share the similar disinfecting root of 3% hydrogen peroxide. One area in which they differ, however, is in the neutralization process. Clear Care and One Step are neutralized with exposure of the peroxide to a platinum-covered disc, while OxySept is neutralized through exposure to a catalase enzyme.
We could stop the comparisons right there, but another important solution feature is the lubricity of the saline following neutralization.
Comfort After Neutralization
We recently performed a study on 65 subjects in which we compared their subjective symptoms of dryness following 2 weeks' use of three soft lens disinfection systems: Opti-Free Express (Alcon), Renu (Bausch + Lomb), and Clear Care. Daily disposable lenses were worn as a “washout” for 2 weeks between the various solutions. Figure 1 shows the dry eye questionnaire results in which subjects reported the symptom of dryness was worse with the hydrogen peroxide than with either of the multipurpose disinfection systems. This was further documented when frequency of blink rate was measured using a high speed eye tracker (Figure 2). If we assume that the more frequent the blink rate the more dry the lens surface, then the Clear Care system demonstrated more dryness.
Figure 1. Subjective dryness results as measured by a dry eye questionnaire.
Figure 2. Frequency of blink rate as measured with a high speed eye tracker.
This feature of neutralized peroxide is something that did not escape the solution chemists at AMO and Sauflon. Both manufacturers incorporate a lubricating agent into their systems to enhance on-eye wetting and to improve patient comfort. However, some great news for Clear Care is that we instruct our patients who are using this system to (following neutralization) apply their lenses with a drop of the Allergan preservative-free Refresh Contacts in the bowl of the lens. We believe the drop serves two functions: first, it increases the lubricity of the lens and has a rather dramatic effect on patients' initial and long-term comfort; and second, it eliminates the 10 to 15 seconds of burning and stinging that some patients experience upon application of their neutralized lenses. We believe this reaction may be an ocular response to very low levels of residual peroxide present on the lens surface. The 10- to 15-second delay probably represents the time it takes for a patient's own catalase-containing tears to neutralize the residual peroxide. CLS
Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Paragon Vision Sciences. Mark André is an associate professor of optometry at Pacific University. He is also a consultant to CooperVision