Contact Lens Care & Compliance
Should Tap Water Be Used to Rinse GP Contact Lenses?
BY MICHAEL A. WARD, MMSC, FAAO
Rinsing GP lenses with tap water is a common practice of GP lens wearers. Does this put GP wearers at risk for microbial keratitis and, most concerningly, for Acanthamoeba keratitis (AK)? Should water be eliminated from all aspects of GP lens care?
The answer is not as simple as it may appear.
Defining the Risks
AK is a rare, potentially blinding infection of the cornea caused by a free-living, water-borne protozoan that is ubiquitous in nature (http://eyewiki.aao.org; Centers for Disease Control and Prevention [CDC],1986). The first major AK outbreak occurred in the mid-1980s and was associated with contact lens use with homemade saline (salt tablets and distilled water) (CDC, 1986). In 2007, the CDC reported increased incidence of AK among contact lens wearers: 85% were soft lens wearers, 7% were GP lens wearers, and 9% did not wear contact lenses. The question of water quality due to lowered concentrations of chlorine was raised (Joslin et al, 2006; Ward, 2009).
The risk of contact lens-associated microbial keratitis increases with continuous wear and when wearing lenses during water activities (Stehr-Green et al, 1989).
Water should never be used with soft contact lenses. Do GP lenses deserve different considerations? At least three major GP lens care products have U.S. Food and Drug Administration (FDA)-approved labeling for use with a tap water rinse. If used, tap water should only be used prior to lens disinfection (Ward, 2009). The FDA and CDC are focusing their efforts to prevent further outbreaks.
Pros and Cons of Using Tap Water with GP Lenses
Following are some points to ponder regarding tap water and GP lenses:
• Water is the “universal solvent” because it dissolves more substances than any other. Its strong solvent properties are related to its ionicity (polarity). Sufficient rinsing force and volume are necessary to remove emulsified contaminants and excess detergents during GP lens rinsing. Salines and multipurpose solution (MPS) products may be used to rinse GPs, but are unlikely to be as effective as water at removing surfactants. The tendency is to use less saline or MPS product for economy, and inadequate rinsing can lead to a toxic reaction at the ocular surface (Ward, 2009).
• Water may contain various levels of bacteria, fungi, and protozoa, and not all water is of equal quality. Dr. Eve Higginbotham insightfully commented in a recent FDA Ophthalmic Devices Panel meeting regarding the quality of tap water: “… ZIP code may be more important than anything else as it relates to sources of water,” (www.fda.gov).
• Rinsing with tap water is a significant associated risk for AK among patients wearing overnight orthokeratology lenses (Watt and Swarbrick, 2005).
• As Dr. Ralph Stone reported during the recent FDA Panel meeting: “While some panel members believed it would be appropriate to eliminate the use of tap water in the regimen, it was agreed that there is no good alternative today,” (Stone, 2014).
It is important for us to remember that contact lens wear is not a sterile event; however, it should be a clean event. Ideally, lens wearers use good hygiene and sterile products, replace lenses as prescribed, and replace cases at least every three months. Reality may be otherwise. Stay tuned as the FDA and CDC focus their efforts to make contact lens wear safer. CLS
For references, please visit www.clspectrum.com/references and click on document #225.
Mr. Ward is an instructor in ophthalmology at Emory University School of Medicine and Director, Emory Contact Lens Service. He is also a consultant or advisor to Alcon and B+L. You can reach him at firstname.lastname@example.org.