Post-Neutralizing Effect of Peroxide Based Contact Lens Disinfecting Solutions

Signature Grand, Davie, Florida, USA

Objective. The objective of this study was to investigate whether or not a peroxide based contact lens disinfecting solution loses disinfecting capacity after prolonged use. Background. Contact lens wearers tend to overuse their disinfecting solutions which may lead to an increased incidence of microbial infections due to increased microbial numbers on the contact lenses. Methods. We tested two peroxide based contact lens disinfecting solutions by inserting 4.5 ml of each contact lens solution into a test tube and then adding 5ul of 400 U/ml catalase (in PBW). Controls contained 4.5 ml of PBW. Each test tube was inoculated with 1 x 107 cells in 0.5 ml PBW. Aliquots were removed from the inoculated solution at intervals of 0, 2, 4 and 6 hrs and plated in triplicate on nutrient agar.The test organisms were ATCC strains of Staphylococcus aureus, Staphylococcus warneri, Serratia marascens, Pseudomonas aeruginosa, Candida albicans, Fusarium solani and Aspergillus sp. Colony counts were made after incubation for 24-72 hrs at 35 C (bacteria) and 25 C (fungi). Results. Both contact lens disinfecting solutions displayed a comparable low level of ability to kill microbial organisms at the time periods and a one log reduction in microbial populations was observed after 6 hrs of incubation. Conclusion. Contact lens disinfecting solutions rapidly lose their disinfecting properties and must be replaced on a regular basis. Patients must be educated that proper ocular hygiene includes timely replacement of their contact lens disinfecting solution along with a strict regimen of contact lens care. Grants. This study was funded by a NSU President’s Research & Development Award (SS & HL).