The Dirt on Hand Washing
BY TIMOTHY B. EDRINGTON, OD, MS, FAAO, & DAWN LAM, MSC, OD
A 2005 nationwide poll by Harris Interactive reported that women (95 percent) are more likely to wash their hands than are men (75 percent) after using the restroom. In this poll, hand washing compliance ranged from a low of 74 percent for baseball fans at Turner Field in Atlanta to 89 percent at Chicago's Shedd Aquarium.
We know that hand washing is an integral component of good contact lens hygiene. Hopefully, hand washing compliance improves when patients receive proper instructions and the instructions are reinforced during follow-up care.
In the recent past we could assume that most patients used soap and tap water to clean their hands. Today, antimicrobial hand sanitizers, which may contain alcohol, are more prevalent. Alcohol is irritating if it comes in contact with the eye. Soft lenses may absorb the alcohol during lens application or during the removal and disinfection process. This may lead to a sustained exposure time with the cornea resulting in symptoms of burning and/or signs of corneal staining.
Hand drying may be accomplished by using cloth or paper towels, warm forced air through a hand dryer or good-old evaporation. Several studies analyzed the efficacy of different methods of hand drying. Though counterintuitive, hot air drying tends to increase the amount of bacterial load on the hands, whereas paper towel drying causes a slight decrease in the bacterial load.
Regardless of method, we recommend that patients thoroughly dry their hands to avoid tap water contamination of their lenses and case. Also, lint free towels will reduce the introduction of foreign bodies to the lens surface.
Sources of Contamination
A study by Mowrey-McKee et al (1992) suggests that lens handling is a significant source of microbial contamination. Stapleton et al (2005) found that a lack of hand washing contributed to patients' increased risk for microbial keratitis. Both Ly et al (1997) and Hart et al (1993) found Staphylococcus epidermidis to be the most frequently isolated bacteria from the surface of soft lenses. This was found regardless of whether lenses were handled by the patient or aseptically.
A study by Willcox et al (1997) suggests that the lids and lashes are also a potential source for Staphylococcus on the surface of soft contact lenses.
The Centers for Disease Control and Prevention Clean Hands Campaign (www.cdc.gov/cleanhands) recommends that it's best to wash your hands for 20 seconds — approximately the time it takes to sing "Happy Birthday" twice.
The CDC recommends to first wet your hands with clean running water, apply non-perfumed soap and lather your hands thoroughly by rubbing them vigorously for 20 seconds. Rinse hands well to remove any remaining soap and loosened debris followed by drying hands completely with a clean, lint free towel. Warm water is a better solvent for soap than cold water is.
It's important to have patients wash their hands before lens application and removal, but it's equally important to remind patients to wash their hands prior to even touching their eyes.
It's also important that patients digitally clean, rinse and air dry their lens storage cases. The solution left behind without proper and regular case cleaning may leave a slimy or sticky residue. During the recent Fusarium concern, it was found that residue from a multipurpose contact lens solution may have contributed to an increased incidence of fungal infections. Strongly recommend that your patients clean their cases daily and replace cases regularly. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #149.
Dr. Edrington is a professor at the Southern California College of Optometry. E-mail him at email@example.com. Dr. Lam is an assistant professor at the Southern California College of Optometry.