Long-Term CL Storage for Part-Time Wearers: Pro-Guard Versus Traditional Polyethylene Case
(Kellee) Leangsok Tea, O.D., Mariam E. Sasani, O.D., Dawn Y. Lam, M.Sc. O.D., F.A.A.O.
Introduction: Statistics show that over 34 million Americans wear
contact lenses and of these, 85% are hydrophilic contact lens wearers.
Contact lens wearers comprise of full or part-time wearers. Part-time
wearers may be more susceptible to ocular infections because of
potential long-term lens storage in contact lens cases. Contamination of
contact lens case has been shown to be a common culprit behind contact
lens contamination leading to contact lens-related bacterial keratitis and
corneal ulcers. In 2006, Ciba developed a new silver impregnated PROGUARD™ contact lens case to minimize contact lens complications due
to lens contamination during storage. This study examines the efficacy
of this new lens case compared to a traditional polyethylene contact
Methods: 20 silver-impregnated cases (Sample A) and 20 traditional
polyethylene cases (Sample B) were inoculated with P. aeruginosa,
Ciba Aquify® solution, and a previously worn (harvested from recruited
soft contact lens wearers >18 years of age) silicone hydrogel lens (O2
Optix). Cases were either incubated for four hours or for one week.
There were 10 control samples per case per time period of incubation.
After the designated incubation periods, solution from each case was
cultured on Cetrimide agar plates. Agar plates were then incubated at
37 degrees Centigrade for 24 hrs to allow time for bacterial growth.
Results: Preliminary data for the four hour incubation period utilized a
diluted titer of P. aeruginosa, and did not yield microbial growth in either
lens cases. Further testing for the one week incubation period utilized a
100% concentration of P. aeruginosa and yielded recordable microbial
growth. Employing a Two-sample T-test to the growth data, a p-value of
0.023 demonstrated a significant difference between the polyethylene
and PRO-GUARD™ contact lens cases.
Conclusion: This study has demonstrated that the advent of the silverimpregnated
PRO-GUARD™ cases may be one solution to the dilemma
of contaminated contact lens cases.