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Microwave disinfection of soft contact lenses
M G Harris1, J E Kirby, C W Tornatore
1Morton D. Sarver Laboratory for Corneal and Contact Lens Research, School of Optometry, University of California, Berkeley.
Abstract:
We evaluated the effectiveness and convenience of microwave irradiation as a method of disinfecting soft contact lenses. Soft contact lenses from each of the four Food and Drug Administration (FDA) categories were placed in sterile vials and immersed in 2 ml of saline which had been contaminated with one of three common species of bacteria. The contaminated lens vials were placed in a standard 600 W microwave oven and exposed to microwave irradiation times ranging from 30 to 180 s. Significant reductions in bacteria colony counts were found after 30 s of microwave irradiation. Few of the bacteria survived 60 s of microwave exposure and none survived 90 s. Our findings indicate that microwave disinfection can be an effective and rapid means of killing bacteria on soft lenses and in the storage solution. However, further studies are necessary to determine the minimum exposure time required, the effect of microwave disinfection on other microorganisms, and the effect of microwave irradiation on contact lens polymers and lens dimensions.
Insights
Microwave irradiation effectively disinfects soft contact lenses, significantly reducing bacteria within 30 seconds. Complete bacterial elimination was observed after 90 seconds of microwave exposure, offering a rapid disinfection method.
Area of Science:
- Ophthalmology
- Microbiology
- Biomedical Engineering
Background:
- Soft contact lens disinfection is crucial for preventing microbial keratitis.
- Current disinfection methods can be time-consuming or require specific chemical solutions.
Purpose of the Study:
- To evaluate the effectiveness and convenience of microwave irradiation for disinfecting soft contact lenses.
- To determine the optimal microwave exposure time for bacterial elimination.
Main Methods:
- Soft contact lenses from four FDA categories were contaminated with common bacterial species.
- Contaminated lenses in saline were exposed to microwave irradiation for varying durations (30-180 seconds).
- Bacterial colony counts were assessed post-irradiation.
Main Results:
- Significant bacterial reduction occurred after 30 seconds of microwave irradiation.
- Minimal bacterial survival was noted at 60 seconds, with complete eradication by 90 seconds.
- Microwave disinfection proved effective against bacteria on lenses and in storage solution.
Conclusions:
- Microwave irradiation is a potentially effective and rapid method for soft contact lens disinfection.
- Further research is needed to establish minimum effective exposure times and assess effects on lens materials and other microorganisms.