Contact Lens Care & Compliance
In-Office Disinfection of Soft Contact Lenses
BY MICHAEL A. WARD, MMSC, FAAO
Most contact lenses fitted today are soft single-use, one- to two-week, and monthly replacement modalities. As such, most lenses that we place on patients’ eyes for evaluation are either immediately discarded or dispensed from stock.
But, what about the occasional patients whom we trial fit with an aphakic, prosthetic, or other specialty lens? How do we clean, disinfect, and store these seldom-used lenses so as to guarantee sterility and patient safety?
Eyecare professionals and industry representatives continue to participate in American National Standards Institute (ANSI) and International Organization for Standardization (ISO) committees that have attempted over the years to establish standards for contact lens reprocessing. ISO Technical Specification 19979:2004 indicates that heat management is preferred over chemical management. It states that for lenses that are compatible with heat, the preferred method is to sterilize the lenses, packed in appropriate solution and a sealed vial, such that the sterility assurance level will be less than or equal to 10−6. It also states that chemical management is achieved by soaking lenses for a minimum of three hours in 3% hydrogen peroxide solution before neutralization, after which lenses should be stored in a preserved solution. Other chemical systems may be qualified as equivalent to 3% hydrogen peroxide by a comparison of D-values obtained for a variety of challenge organisms (ISO, 2004).
However, to my knowledge, there are no current U.S. government guidelines for disinfecting and storing in-office, reusable soft trial lenses. The last Centers for Disease Control and Prevention recommendation was published in 1985 and was specific for HIV contamination (http://wonder.cdc.gov/wonder/prevguid/m0000602/m0000602.asp).
One method that has been recommended is to clean, rinse, and treat a trial lens initially with 3% H2O2 (three-hour soak prior to neutralization), followed by storage in a multipurpose solution. This may be adequate assuming that no biofilm has formed in the storage vial and that the multipurpose storage solutions are replaced at least monthly. This practice assumes flawless aseptic techniques and sufficient efficacy and stability of the disinfecting solution over time. An additional concern of lens storage in chemical disinfectants is possible toxicity or hypersensitivity reactions when later placed on the eye.
There is one practical lens reprocessing method that guarantees sterility: steam under pressure (autoclave), which eliminates all possible microbial contamination. Autoclaving also provides a reasonable shelf life, thus removing the necessity to replace storage solutions monthly.
What We Do in Our Practice
We reprocess all reusable soft contact lenses in the following manner prior to reuse:
1) Digital cleaning with extra-strength, 15.7% alcohol/surfactant-based cleaner.
2) Rinse with nonpreserved, sterile saline.
3) Return lens to original vial and fill with nonpreserved saline; seal vial.
4. Autoclave; label with expiration date one year out.
High-water-content lenses may be reprocessed only a limited number of times before they should be replaced, and occasionally a vial will break. Because all trial lenses require periodic replacement, these costs should be factored in as overhead. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #233.
Mr. Ward is an instructor in ophthalmology at Emory University School of Medicine and Director, Emory Contact Lens Service. You can reach him at email@example.com.