The development of evidence based contact lens storage case cleaning guidelines

Contact lens storage case contamination is a significant risk factor for contact lens related complications such as infection and inflammation. Currently, there are no evidence-based data to support current lens case cleaning guidelines. This represents a major challenge to eye care practitioners in educating lens wearers regarding hygiene practices to limit microbial contamination of lens cases and to reduce the risk of microbial related adverse events. The objective of this thesis was to develop an evidence-based contact lens case cleaning guideline to limit microbial contamination of contact lens cases.A cross-sectional study was conducted to characterize the scope of lens hygiene behaviour, followed by a microbiological study adopting a new sampling method to assess microbial contamination in lens cases. A systematic literature review and a survey were undertaken to establish the extent of current lens case cleaning guidelines available from authoritive sources. In vitro studies investigated the effectiveness of various cleaning methods commonly carried out by lens wearers. Based on this, a new guideline was proposed and finally, the effectiveness of the new lens case cleaning guidelines in reducing microbial contamination was tested in a clinical trial. A number of key findings were established from the above studies. Lens case hygiene practice is inadequate in lens wearers. Lens case contamination is common, and the rate and the profile of microbial contamination may be spatially distributed differently within one lens well, with aerobic organisms predominantly found at the air/fluid interface and facultative anaerobic within the case fluid. Inconsistent and inadequate contact lens case cleaning guidelines persist amongst industry, regulatory authority, and practitioners. Amongst lens case cleaning methods, mechanical friction is essential in removing biofilm. Hence, the most effective cleaning regimens proven in vitro and in vivo are rubbing, rinsing with disinfecting solution, tissue-wiping and air-drying lens cases. Lens cases should be air-dried face down to minimize air-borne microbial contamination. The topography and/or material of a lens well determine the ease of biofilm removal and surface contamination. The newly developed lens storage case cleaning guidelines were shown to limit microbial contamination of lens cases and can be used to educate lens wearers on how to clean lens cases. Also the study provides advice to manufacturers who design lens care products