Reduction of disinfection efficacy of contact lens care products on the global market in the presence of contact lenses and cases

Abstract

ObjectiveSight-threatening infections can be caused by pathogenic micro-organisms colonising the cornea, leading to microbial keratitis (MK). These micro-organisms can be introduced to the eye via improper contact lens use and care. MK can also result from ineffective contact lens care solutions (CLCs), even if the patient is following best practice guidelines. Therefore, it is critical to understand the differences between the effectiveness of popular CLCs on the global market.Methods and analysisFollowing the International Standards Organisation standards 14 729 and 18259, bacteria (Pseudomonas aeruginosa, Serratia marcescens, Staphylococcus aureus), fungi (Candida albicans, Fusarium strains) and Acanthamoeba strains were inoculated into each CLC with and without contact lenses, and held for the manufacturer’s stated disinfection time. Plate counts were conducted to determine the number of surviving micro-organisms.ResultsAll CLCs examined met the primary log reduction criteria during stand-alone testing for Pseudomonas, Staphylococcus, Candida and Fusarium. renu Multiplus, All Clean Soft, and Kombilösung Super did not meet the primary criteria when challenged with Serratia. Only OPTI-FREE Express exceeded 4 log reduction for both strains of Acanthamoeba tested. We noted a substantial reduction in disinfection efficacy when CLCs were challenged with Fusarium in the presence of lenses and cases versus stand-alone testing. OPTI-FREE Express demonstrated significantly less net log reduction loss than the other four CLCs tested.ConclusionOf the popular CLCs on the global market, the product which relies on dual biocides polyquaternium-1 and myristamidopropyl dimethylamine demonstrated the highest disinfection efficacy in microbial disinfection challenges in the absence and presence of contact lenses.

Complete Recovery of Acanthamoeba Motility among Surviving Organisms after Contact Lens Care Disinfection

“…More critically, similar to previous studies noting that lenses and cases reduce CLC effectiveness due to biocide uptake [ 20 , 21 ], we noted in many places that in cycled PHMB (PHMB which has not been replaced after nightly use—the same aliquot of solution was used for nightly lens disinfection for 7 days, to simulate the real-world scenario of how many patients might misuse their CLCs), amoeba demonstrated significantly greater movement than in fresh PHMB. That is to say, cycled CLCs provided little to no disinfection efficacy, and were at many times not dissimilar from control solutions which contained no biocides.…”

“…As evidenced by the increase in the number of investigations into, and publications on Acanthamoeba keratitis in recent years [ 5 , 6 , 8 , 10 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], this is a devastating and potentially sight-threatening disease. However, until now there has been a lack of investigation regarding the behavior of Acanthamoeba on contact lenses, both in and out of contact lens care disinfecting solutions (CLCs).…”

The Role of Biofilms in Contact Lens Associated Fungal Keratitis

“…It has been proposed that fungal cells causing CLAFK originate from those residing in CL solutions or lens cases [23,66], using CLs as an intermediate mediator to reach the human cornea [67]. Proposedly, fungal cells from external environments contaminate CLs and lens cases, forming monolayer/microcolony biofilms on their surfaces that survive overnight CL disinfection [18,68] (Figure 1A). Small cell clusters from the biofilms can be brought to the proximity of the cornea and survive the dynamic and naturally antimicrobial ocular environment (Figure 1B).…”

Comparative Evaluation of Pseudomonas aeruginosa Adhesion to a Poly-(2-Methacryloyloxyethyl Phosphorylcholine)-Modified Silicone Hydrogel Contact Lens

“…These include outbreaks of the comparatively rare pathogens Fusarium solani [ 18 , 19 ] and Acanthamoeba [ 20 ]. It is widely understood, and now codified in ISO 18259, that the efficacy of multipurpose disinfection solutions (MPDS) can depend upon the materials of the contact lens, contact lens storage case, and the presence of soiling agents [ 21 , 22 , 23 , 24 , 25 ]. However, additional disinfection variability can arise when real-world patient practices, such as reusing or topping off contact lens care solution, dilute the effective concentration of biocides.…”