Reviews Supplements Alcon Clear Care : Page 1

STUDIES STUDIES IN CONTACT IN CONTACT LENS LENS CARE CARE 1 A Fresh Look at One-Step Hydrogen Peroxide Lens Disinfection Robin L Chalmers, OD Hydrogen peroxide-based contact lens disinfection systems are known for their exceptional disinfecting effi cacy and ocular biocompatibility. These traits have enabled hydrogen peroxide disinfection to remain an important option for contact lens wearers over almost three decades. In that time, peroxide disinfection grew to become the market leader and then, with the advent of “no-rub” multi-purpose disinfecting solutions, declined substantially for some years. Yet one-step peroxide disinfection has endured, and today it again holds a sizeable and steadily growing share of the market. Over the years, the advantages of peroxide disinfection have been proven in many types of studies. 1-3 Human clinical studies have characterized the eye’s tolerance for low levels of residual peroxide to which contact lens wearers may be exposed. And laboratory research has enabled developers to design effective neutralization systems and formulate the peroxide solution and system for maximum comfort as well as effi cacy in cleaning and disinfection. A review of these studies shows how hydrogen peroxide-based contact lens care products in general, and CLEAR CARE ® Cleaning & Disinfecting Solution in particular, can combine exceptional disinfection and cleaning with reliable neutralization of residual peroxide for safe and comfortable contact lens wear when used as directed. When I entered contact lens research in the 1980s, one of my fi rst research assignments was to explore the ocular effects of residual hydrogen peroxide (H 2 O 2 ) from the then relatively new peroxide-based contact lens disinfection systems. 4,5 In the ensuing decades, the popularity of peroxide-based contact lens disinfection grew substantially and then waned, almost to the point of being an afterthought among contact lens disinfection systems. In recent years, however, H 2 O 2 has reemerged as an important option for contact lens care. And for good reason: The large body of peer-reviewed research on H 2 O 2 contact lens disinfection shows that peroxide’s recent gains in respect and market share rest on a solid base of CLEAR CARE ® : Clear Advantages Hydrogen peroxide is a powerful disinfectant, with high effi cacy even against microbial biofi lms Neutralization breaks hydrogen peroxide into benign byproducts: water and gaseous oxygen Enzymes in the tears and ocular surface tissues are able to rapidly neutralize residual peroxide The CLEAR CARE ® System’s case is designed for controlled, thorough neutralization, leaving low levels (5 to 60 ppm) of residual H 2 0 227 CLEAR CARE ® use has consistently been associated with low rates of corneal staining and has not been signifi cantly associated with corneal infl ammatory events 9,10 CLEAR CARE ® users demonstrate compliance and loyalty, and enjoy excellent comfort on lens insertion and throughout the day 11,22,30,43,44 scientifi c evidence, not to mention years of continued use by many loyal contact lens wearers. The Eye and H 2 O 2 In 1989 and 1995 I published two review papers explaining that, more than just a man-made disinfectant, H 2 O 2 is generated in many normal physiological processes. Since it is a common physiological by-product, the human body is well equipped to metabolize H 2 O 2 in low concentrations (up to 800 ppm in topically applied ophthalmic drops). 5,6 In 1993, Michael Riley and Graeme Wilson, esteemed corneal physiologists, wrote a review of the safety of topically applied H 2 O 2 on the ocular surface, making it clear that both the tear fi lm and the ocular surface tissues have an abundance of enzymes capable of rapidly neutralizing dilute H 2 O 2 . 5,7 With colleagues, I determined the human detection threshold for buffered isotonic H 2 O 2 and the speed with which residual H 2 O 2 is neutralized by the ocular surface. 1,4 Wilson and Riley then used a rabbit model to conduct in-vivo and in-vitro studies determining the safety of topical exposure to H 2 O 2 and the degree to which H 2 O 2 is able to penetrate an intact rabbit cornea. 2,7,8 Taken as a whole, this body of work clearly demonstrates that exposure to low levels of H 2 O 2 Sponsored by Alcon

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