Even with the use of multipurpose or hydrogen peroxide-based systems, contact lens case contamination is common (Dantam et al, 2016; Wu et al, 2015; Thakur and Gaikwad, 2014), occurs rapidly, can persist (Dantam et al, 2016), and is associated with microbial keratitis and sterile corneal infiltrates (Vijay et al, 2015). A contaminated case can act as a reservoir for microorganisms that could potentially negate healthy lens wear and lead to sight-threatening adverse events (Wu et al, 2015). The variety of lens case contaminants may exceed that for lenses (Szczotka-Flynn et al, 2010), and cases provide an ideal environment for biofilm development. In fact, inadequate case cleaning can increase the risk of a lens-related infection by approximately four times (Efron and Morgan, 2017). One review reported that the rate of case contamination is often more than 50% (Wu et al, 2015). The most common bacteria recovered from lens cases were Coagulase-negative Staphylococcus, Bacillus spp., Pseudomonas aeruginosa, and Serratia marcescens (Wu et al, 2015).

Proper Cleaning

The type of contact lens case used can help prevent infection; a simply designed case (non-ridged wells) or a cylindrical case is easy to clean (Wang et al, 2011; Wu et al, 2011).

The most effective way to clean a storage case and remove biofilm with a multipurpose solution is to incorporate manual rubbing or wiping of the case with a paper towel. Once clean, air dry the case face down rather than face up (Vijay et al, 2015; Tilia et al, 2014). This process removes excess moisture and decreases the risk of microbial keratitis and airborne contamination (Wu et al, 2015; Hall and Jones, 2010). Lens cases should not be stored in the bathroom or near the toilet to reduce contamination (Wu, Zhu et al, 2010).

Poor case hygiene and cleaning is common (Wu et al, 2011; Kuzman et al, 2014) and may be further heightened by a lack of regular case replacement (Dumbleton et al, 2013; Cope et al, 2017; Abbouda et al, 2016). Monthly case replacement is recommended (Cho et al, 2009).

Avoid water for all contact lens wear and care, especially due to the risk of Acanthamoeba, which can cause sight-threatening vision loss. One study reported that two-thirds of individuals used tap water to clean cases (Dumbleton et al, 2013). Despite clear recommendations that tap water should be avoided, a recent survey indicated that 24% of practitioners (n = 8/33) recommended boiled or warm water for case cleaning (Hind et al, 2020).

To help with this, creative reminder cues may be beneficial. A recent study demonstrated that a simple “no water” graphic on contact lens paraphernalia can reduce water exposure behaviors and environmental contact lens case contamination (Stapleton et al, 2021).

Mixed Messages

However, mixed messages by practitioners, professional and regulatory bodies, and manufacturers may contribute to poor case hygiene (Hind et al, 2020; Wu, Carnt et al, 2010). Case replacement recommendations vary between one-to-three months, and few mention rubbing cases and storing them face down.

In addition to prescribing specific lenses and recommending a lens care solution, practitioners should educate patients to clean and disinfect their cases daily, avoid the use of tap water, avoid topping off solutions, consider the location and how the cases are stored during the time of lens wear, and emphasize the importance of good hand hygiene when handling lens cases. Also remind patients that contact lens cases must be replaced monthly.

Improved lens case hygiene will substantially reduce pathogenic microbe contamination of both cases and eyes and will thus promote healthy lens wear. CLS

For references, please visit www.clspectrum.com/references and click on document #312.