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David McCanna, Masooda Bidar, Lakshman Subbaraman, Lyndon William Jones; The Effect of Artificial Tear Solution and Organic Load on the Efficacy of Contact Lens Disinfectant Solutions. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3075.
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© ARVO (1962-2015); The Authors (2016-present)
Artificial tear solutions (ATS) and organic load components contain components that can bind to chemical disinfectants and neutralize their ability to kill microorganisms. In contact lens (CL) cases, microbial biofilms can develop that are resistant to disinfectants, and the addition of organic molecules can enhance the resistance of these biofilms. A study was performed to determine the effect of organic molecules on the efficacy of two antimicrobials.
Two different organic solutions were tested in this study. The first solution was an ATS composed of proteins, lipids and salts in proportions that closely mimic their composition in the human tear film. The second formulation is the one described in FDA/ISO testing methods, which is composed of heat-killed yeast cells and heat-inactivated bovine serum (FDA organic load). Staphylococcus aureus (Sa) was allowed to adhere to the surface of the CL cases for 24hrs, after which they were washed to remove non-adherent cells. Disinfecting CL solutions were then added to lens cases and to lens cases containing either ATS or FDA organic load. Lens cases treated with only PBS served as a viability control. Five lens cases were evaluated for each treatment. A one-way ANOVA with a Bonferroni post-hoc was performed with significance level of 0.05.
The FDA organic load reduced the anti-microbial efficacy of two different disinfecting solutions (p<0.01). For the two solutions, a 59.6% decrease in the efficacy of polyaminopropyl biguanide (PAPB) solution (0.00001%) and a 40.9% decrease in the Polyquat/Aldox (0.0006 %/0.00036%) solution was observed. The ATS did not reduce the efficacy of the PAPB and polyquat/aldox disinfecting solutions (p>0.05).
This study showed that contamination of CL cases with the FDA organic load can significantly decrease the anti-microbial efficacy of CL care solutions. However, organic molecules in an ATS did not significantly reduce the anti-microbial efficacy of these formulations. The use of the FDA organic load as a model for lens case contamination may not be appropriate, as an ATS which models contamination of a CL from the tear film did not significantly reduce the anti-microbial efficacy of two anti-microbial disinfectant solutions.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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