Microbial Contamination of Contact Lenses, Lens Care Solutions, and Their Accessories: A Literature Review

Abstract

Purpose A contact lens (CL) can act as a vector for microorganisms to adhere to and transfer to the ocular surface. Commensal microorganisms that uneventfully cohabitate on lid margins and conjunctivae and potential pathogens that are found transiently on the ocular surface can inoculate CLs in vivo. In the presence of reduced tissue resistance, these resident microorganisms or transient pathogens can invade and colonize the cornea or conjunctiva to produce inflammation or infection. Methods The literature was reviewed and used to summarize the findings over the last 30 years on the identification, enumeration, and classification of microorganisms adherent to CLs and their accessories during the course of normal wear and to hypothesize the role that these microorganisms play in CL infection and inflammation. Results Lens handling greatly increases the incidence of lens contamination, and the ocular surface has a tremendous ability to destroy organisms. However, even when removed aseptically from the eye, more than half of lenses are found to harbor microorganisms, almost exclusively bacteria. Coagulase-negative Staphylococci are most commonly cultured from worn lenses; however, approximately 10% of lenses harbor Gram-negative and highly pathogenic species, even in asymptomatic subjects. In storage cases, the incidence of positive microbial bioburden is also typically greater than 50%. All types of care solutions can become contaminated, including up to 30% of preserved products. Conclusions The process of CL-related microbial keratitis and inflammation is thought to be preceded by the presence or transfer or both of microorganisms from the lens to the ocular surface. Thus, this detailed understanding of lens-related bioburden is important in the understanding of factors associated with infectious and inflammatory complications. Promising mechanisms to prevent bacterial colonization on lenses and lens cases are forthcoming, which may decrease the incidence of microbially driven CL complications.

Ceragenins as Mimics of Endogenous Antimicrobial Peptides

“…AMPs are present in the conjunctival sac, and covalent attachment of AMPs to contact lenses has been shown to inhibit bacterial biofilm formation [92]. However, the costs of AMPs and their susceptibility to proteases complicates their use in contact lenses.…”

Contact Lens-Related Infectious Keratitis: Review of 29 Cases

“…Auto-medication of patients before hospitalization and the lack of coordination with the laboratory may decrease the chance of isolating a germ as Open Access Library Journal cited by Benhmidoune [3]. Due to their low specificity, contact lenses or contact lens cases culture will be mainly useful in the etiological diagnosis when corneal scratch culture returns negative as demonstrated elsewhere [17]. The first etiology of infectious keratitis in contact lenses users worldwide was bacterial (range 80% -94.2%), followed by amoebic infection (1.5% -17.7%), followed by fungal infection (1% to 4.3%) as described in these reports [3] [10] [13] [18].…”

Potential application spectrum of microbial proteases for clean and green industrial production

“…Films formed over the lenses provide a surface for the adhesion of opportunistic pathogens like Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis (Dutta et al 2012). Adhesion and colonization by microorganisms, particularly bacteria, on contact lenses have been implicated in several adverse events including microbial keratitis (Willcox and Holden 2001), contact lens-related acute red eye (Szczotka-Flynn et al 2010), contact lens peripheral ulcer (Wu et al 2003) and infiltrative keratitis (Szczotka-Flynn et al 2010). Therefore, cleansing of contact lenses is utmost important.…”