Evaluation of prevention and disruption of biofilm in contact lens cases

Abstract

Purpose The presence of biofilm in the lens case has been shown to be a risk factor for contamination of lenses and consequently microbial keratitis. This study aimed to evaluate effectiveness of solutions for rigid contact lenses in prevention and disruption of biofilm in lens cases and methods for biofilm detection. Method This study adopted a stepwise approach to evaluate effectiveness of four rigid lens disinfecting solutions against biofilm. These included two polyhexamethylene bigiuanide (PHMB) solutions and a chlorhexidine/PHMB‐based solution, as well as a novel povidone‐iodine formulation. The presence of biofilm following exposure to the solutions was assessed using both crystal violet (CV) staining and MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide) viability assay, taking into account the effect of lens case design. Three lens case designs, conventional flat, large bucket type, and cylindrical cases, were investigated for the ability to trap stain and allow biofilm formation. Results Considerable differences were noted between solutions in their ability to prevent and disrupt biofilm (p < 0.001). Lens case design greatly influenced optical density (OD) measurements even in negative controls, as cylindrical cases trapped more stain, increasing OD readings. Correcting for this factor reduced variations, but could not differentiate between residues and biofilm. MTT assay revealed that both povidone‐iodine and chlorhexidine‐containing solutions could effectively kill > 95% of organisms, whilst PHMB‐based solutions were less effective with up to 55% of staphylococci and 41% of Pseudomonas surviving at 24 h. Conclusion Biofilm can rapidly form in lens cases and may not be killed by disinfecting solutions. Of the solutions tested, none were able to prevent biofilm formation or disrupt established biofilm, but those containing chlorhexidine or povidone iodine were able to penetrate the biofilm and kill organisms. Assessment of biofilm by CV assay may be confounded by lens case design. Whilst CV assay can demonstrate presence of biofilm, this technique should be accompanied by viability assay to determine bactericidal activity.

BCLA CLEAR - Orthokeratology

“…the adhesion and growth of microbes within a self-produced matrix material). Several MPS have a limited effect on biofilm formation, leaving a risk of infection [179][180][181]. However, this could be addressed by using a combination of iron-chelating agents, which have demonstrated success in the removal of bacterial biofilms within contact lens cases [182].…”

“…Povidone-iodine has been used for decades for wound healing and pre-surgical prophylaxis [194,195] and resistance to povidone-iodine has not been reported [196], despite long term exposure. The novel povidone-iodine-based solution has also been shown to be able to effectively penetrate biofilms formed in contact lens cases and kill the organisms contained within them [181].…”

The role of Acanthamoeba spp. in biofilm communities: a systematic review

“…Some bacteria, not all, utilize "quorum sensing" (QS) as a signaling chemical, communicator, and regulator of biofilm formation and the expression of virulence factors (Tortora 2010a(Tortora , 2010b. Biofilms are found in aqueous environments on both biotic and abiotic surfaces such as rocks, food, teeth, the insides of pipes, and medical devices (e.g., prostheses and implants), including contact lenses and lens cases (Tortora 2010a;Cho and Boost 2019).…”

Comparison of compliance with care procedures performed by orthokeratology wearers and their parents and factors affecting compliance

“…38,39 Rubbing the lens case helps to remove biofilm, which may not be adequately removed by most lens care solutions. 40 The importance of regular replacement of the lens case to eliminate a major source of contamination has led to some researchers suggesting monthly replacement rather than 3 months as recommended by the FDA. 41 Manufacturers usually include free lens case together with lens disinfecting solution, so practitioners should encourage wearers to replace their lens case with every new bottle.…”