Case Closed: A Review of Contact Lens Case Care
LENS CASE CARE
Case Closed: A Review of Contact Lens Case Care
Inconsistencies in lens case care recommendations put contact lens wearers at risk for infection.
By Nicole Olboeter, BSc, & Siblle Scholtz, PhD
In this day and age, contact lenses are an almost obvious choice for vision correction. Nevertheless, severe infections constitute a recurring issue, due mostly to patient carelessness or ignorance. Contact lens care—more specifically, contact lens case hygiene—is often perceived as a tedious chore, the result being that users often either fail to follow the appropriate steps altogether, deviate from the process, or carry it out in an inconsistent manner. These steps, however, are fundamental to ensuring long-term, satisfactory, and complication-free contact lens wear.
In industrialized countries, contact lens wear is deemed the highest-ranking risk factor for microbial keratitis (MK) (Dart et al, 1991). Contact lenses affect the development of infections, with the lens material serving as a vector for microorganisms, favoring the subsequent adhesion of pathogens to the ocular surface. The presence of microorganisms in the eye is, however, necessary and does not automatically lead to serious infections (Das et al, 2007; Martins et al, 2002; Mela et al, 2003). For more than 20 years now, numerous risk factors involved in the development of MK have been identified and have been confirmed as such through a number of studies dating up to 2008 (Poggio et al, 1989; Cheng et al, 1999; Stapleton et al, 2008). These risk factors range from overnight wear to inadequate contact lens case care and limited experience with contact lenses, all the way to socio-economic status. Poor contact lens case hygiene raises the probability of eye infection by a factor of 3.7 (Stapleton et al, 2008). On average, inadequate lens case hygiene is thought to be a significant risk factor with regard to MK infections worldwide and can also be linked to the presence of sterile infiltrates in the cornea (Bates et al, 1989).
The Key Role of Lens Cases
Numerous studies on the microbial contamination of contact lens cases describe colonization by bacteria, fungi, viruses, and Acanthamoeba (Gray et al, 1995; Pens et al, 2008; Devonshire et al, 1993; and others—full list available at www.clspectrum.com). Depending on the author, case contamination rates range from 19 percent to 81 percent with bacteria, 4 percent to 24 percent with amoeba, and 24 percent to 59 percent with fungi. The most frequent pathogens linked to poor case hygiene are Pseudomonas, Serratia, Staphylococcus, Acanthamoeba, and Fusarium (Boost et al, 2008; Margolis and Whitcher, 2006; Chalupa et al, 1987).
Even at very low concentrations, pseudomonads are able to trigger MK (Chalupa et al, 1987; Stapleton and Dart, 1995) and lead to significant loss of vision. It has been possible to isolate Serratia from corneal ulcers, and Staphylococci were found in contact lens cases belonging to patients who had suffered from MK (McLaughlin-Borlace et al, 1998). The distinguishing features of Acanthamoeba are on the one hand their ubiquity and on the other their ability to cause major eye infections, carrying the highest known risk for the eye (Illingworth and Cook, 1998; Lorenzo-Morales et al, 2005; Seal et al, 1992). Fungal spores from the Fusarium species can lead to painful keratitis and likewise also to significant loss of vision (Margolis et al, 2006; Alfonso et al, 2006; Thomas, 2003).
Not only can these pathogenic microorganisms cause severe damage to the eyes of contact lens wearers, but some of these germs are also able to generate protective biofilms (Costerton et al, 1987). Biofilms significantly impair the effectiveness of disinfectant contact lens cleansers because they constitute a means by which the relevant microorganisms become resistant to the antimicrobial components of the solutions used (Dart, 1997).
A Search for Consensus With Case Care
Contact lens care guidelines are constantly being updated and adapted to incorporate new findings. Recommendations from eyecare professionals, the industry, and the U.S. Food and Drug Administration (FDA) are consistent as well as easy to follow for any contact lens wearer.
However, the same cannot be said of the instructions and directions regarding contact lens case care, which is the most effective manner to prevent microbial colonization and which was originally described as rinsing the case with hot tap water and leaving it to air dry (Larragoiti et al, 1994). Following the multiplication of Acanthamoeba infections, rinsing with tap water is no longer recommended (Larkin et al, 1990; Seal et al, 1999). In addition to the wide-ranging, classic cylindrical and flat lens cases, lens cases impregnated with silver ions that are meant to inhibit biofilm formation are now available. There is, however, insufficient scientific evidence to support the effectiveness of these cases in our opinion.
Given the major discrepancies in lens case hygiene guidelines, an Australian study has undertaken to shed more light upon the various care instructions and to ensure their consistency in practice by joining forces with eyecare practitioners (Wu et al, 2010). They examined manufacturers' instructions provided on the packaging and instruction leaflets of five contact lens care solutions available on the market and also compiled FDA recommendations, which are freely available on the Internet to anyone interested. A survey in which 77 optometrists took part was then carried out to compare the consistency of these instructions with practice.
Inconsistent Case Care Recommendations
Why make things easy when they could be difficult? The survey mentioned above found inconsistent recommendations regarding contact lens case care. To what extent do the industry, authorities, and contact lens specialists actually agree in terms of these recommendations?
The Industry Four out of five of the care products tested recommended rinsing the contact lens case with a disinfecting solution. The only exception was for a peroxide system, which advised rinsing the case with sterile saline. None of the manufacturers provided any specific indications regarding whether or not the contact lens case used should, for instance, be wiped or rubbed. The general standard regarding the frequency with which to replace the case ranged from “every month” to “as soon as a new care product pack is opened.”
FDA The FDA recommended rinsing the contact lens case with a disinfecting solution and leaving it to air-dry, hollow side (“face”) down. There was no indication as to whether or not the case should be wiped clean, and the recommended replacement frequency ranged from every three to every six months.
Optometrists More than half (52 percent) of all optometrists who participated in the survey recommended rinsing the contact lens case with disinfecting solution, while 30 percent also advised wiping the case. Seventy-seven percent of all participants agreed that the case should then be air-dried, with 42 percent recommending positioning the case hollow side up; 31 percent gave no recommendation as to how to position the lens case. Five percent of all optometrists advocated once-weekly cleaning of the case with a toothbrush. The recommended case replacement frequency also ranged from once monthly to every six months (Wu et al, 2010).
Although both the information leaflets provided with the cleaning solutions studied as well as the FDA itself recommended rinsing used contact lens cases with a disinfecting solution, information leaflets from one peroxide product and 36 percent of all optometrists differed in their recommendations, favoring sterile saline instead. Thirty percent of all optometrists recommended wiping the lens case, although no reference to this particular step in contact lens case care was made in any official sources. Following the rinsing of the container, air-drying was typically recommended as the next step. While the FDA was highly specific in stating that the position of the case during drying should be “face down,” industry recommendations provided no indication whatsoever regarding the drying position, and optometrist recommendations proved highly divergent. Recommended case replacement intervals varied between once monthly and twice yearly, whereupon it was possible to prove that replacing the case at regular intervals resulted in significantly reduced contamination rates (Gray et al, 1995).
What Can and Should Be Done?
Inconsistent data from various sources is precisely what leads to confusion in inexperienced contact lens wearers and undermines the value of lens case care in the perception of contact lens wearers.
Reliable lens case care is essential, as the container provides an inexhaustible reservoir for potentially pathogenic microorganisms (Cheng et al, 1999; Mayo et al, 1987). When it comes to contact lens care, contact lens wearers give lens case hygiene very little thought (Radford et al, 1993), despite contaminated cases constituting a major potential health risk to eyes of contact lens wearers: contact lens cases register the highest contamination rates (Yung et al, 2007) and levels (Mayo et al, 1987) when compared with any other contact lens accessories.
It is therefore especially important for every contact lens wearer to be given simple, easy-to-follow, consistent recommendations regarding contact lens case cleaning. This, surely, is the duty of the industry and research institutions. This also applies to all contact lens practitioners, who must provide their contact lens wearers with up-to-date and practical care guidelines through technical training and raised awareness.
Because the correlative inconsistencies are unlikely to be imminently eradicated, we advocate following the care recommendations issued by the FDA (www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PatientAlerts/ucm064695.htm; www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/HomeHealthandConsumer/ConsumerProducts/ContactLenses/ucm062584.htm) as follows:
● Store your contact lenses in the appropriate [care system and (Amendment statement by Authors)] lens cases.
● Clean and rinse your contact lens case with sterile contact lens cleaner after each use (never use tap water).
● Leave the open case to air-dry after each use. You can also leave the container to dry “face down” to allow any excess solution to drain off.
● Contact lens cases can constitute a source of bacterial colonization.
● Replace your contact lens case at least after every three months [of use (Amendment statement by Authors)].
Compliance with the recommended contact lens care steps ensures long-term, successful contact lens wear for both eyecare practitioners and patients. Compliance and contact lens care are closely linked. Good compliance on the part of contact lens wearers constitutes the basis for comfortable contact lens wear and also helps prevent the discontinuation of contact lens use. Safe and efficient contact lens care systems can make a valuable contribution toward this, but we must also include clear and efficient instructions on caring for contact lens cases. Aside from all of the care measures recommended thus far, replacing the lens case on a regular basis constitutes another essential contribution to reducing biofilm formation in contact lens cases and therefore represents a fundamental step in contact lens container care—along with manual cleaning, disinfection, protein removal (if applicable), and (re)wetting.
Even though mankind has made outstanding progress in the fight against “microbes”—the significance of which must not be undermined—Pasteur's words have retained a frighteningly powerful significance even in our day and age:
“It is the microbes who will have the last word” (Louis Pasteur, Czichos J, 1987).
Further information regarding FDA care instructions for contact lenses is available on www.fda.gov. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #184.
|Nicole Olboeter is an employee of Rodenstock, Germany. She has a Bachelor of Science in Ophthalmic Optics/Optometry, and several years of experience in the ophthalmic Medical Device industry in several scientific positions.|
|Dr. Scholtz is an employee of Abbott Medical Optics, Germany. She is a biologist and chemist with a PhD in Medicine and almost 20 years of experience in medical devices used in ophthalmology. She has written numerous scientific articles on ophthalmology and optometry.|
Contact Lens Spectrum, Issue: March 2011