contact lens care
The Forgotten Lens Care Step
BY JENNIFER L. SMYTHE, OD, MS, FAAO
Caring for contact lenses has become incredibly simple. With the advent of contemporary no-rub, single-bottle systems, multiple steps are no longer necessary. Gone is the need for regular digital daily cleaning, separate weekly enzymatic routine and, for the most part, the never-ending power wash rinsing cycles.
However, one crucial step is probably the most overlooked element of routine lens care: taking care of the lens case. We have all encountered the immaculately groomed patient who cites his lens care routine with meticulous precision and then during the exam, pulls out a most colorful case: pink hues of serratia, fuzzy greenish-gray fungus and black dirt in the cracks and crevices. No matter how simple lens care becomes, we must still discuss contact lens case care with patients.
Have patients clean and replace their cases often to avoid microbial
Too Common for Comfort
Campbell and Caroline have shown that case contamination is not a rare phenomenon. From 91 randomly selected patient cases they found that nearly 50 percent cultured positive. Microbial growth was positive in 43 percent of the cases that came from patients who were seemingly compliant based on their description of their lens care routine.
As expected, the incidence of growth was even higher in a group of noncompliant patients. Sixty percent of their cases were contaminated. Cases of infectious keratitis secondary to microbial contamination of the lens case have been reported.
The Mighty Biofilm
Bacteria can be tough survivors and can develop specific mechanisms that help them survive even in the presence of fresh disinfecting solutions. Their principal survival strategy stems from their ability to attach to surfaces, such as the inside of the contact lens case, and then to subsequently produce biofilm.
Bacteria attached to surfaces exhibit different nutrient uptake characteristics than the free flowing organisms suspended in the lens care solution. This means that the inhabitants that live on the case walls can have a greater impact on the contact lens. Bio-film is an exopolysaccharide glycocalyx slime that the bacteria cells secrete. This slime protects the bacteria from adversities in the environment including the lens care disinfecting solutions, and, within the slime, bacteria replicate and are able to live off of one another.
Frequent case replacement would be ideal. Some manufacturers even include a new case with their retail-size solutions. Remind patients to discard their old cases with their empty bottles. Thrifty patients may not realize that even though the old case looks fine, it is still a breeding ground for microorganisms.
Rub is Still Required
Unfortunately, frequent case replacement is not the sole answer. In Campbell and Caroline's study, nine of the 15 lens cases that were less than one month old showed positive growth. Biofilm will be secure and thriving within seven days, therefore routine case cleaning is critical. For an efficacious and complete lens care regimen, instruct patients to:
- Rinse the case daily and allow it to air dry with the lids off
- At least once each week, before rinsing the case, digitally scrub both the inside and outside of it with a surfactant cleaner.
Dr. Smythe is an associate professor of optometry at Pacific University and is in private group practice in Beaverton, Oregon.