contact lens care
In-Office Hydrogel Contact Lens Disinfection
The contact lens market is healthy and growing. The majority of soft contact lenses fit today are disposables: approximately 65 percent in two-week, 24 percent in 30- to 90-day planned replacement and six percent to nine percent in annual replacement (HPR 2003). This means that 90 percent or more of the time, the trial lens we evaluate on a patient's eye we either discard or dispense from stock. This is good news for patient safety. But, what about the occasional patient 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 ensure patient safety?
Eyecare practitioners and industry representatives have participated in ANSI committees that have attempted to establish standards for contact lens reprocessing. An ANSI proposal document dated October 1999, and later adapted by AOA, states, "Steam sterilization may be used to terminally sterilize trial contact lenses between patient fittings. The sterility assurance level (SAL) shall then be equal to 10-6 or less.
Trial contact lenses may also be subjected to high level disinfection using a hydrogen peroxide system which includes a two-hour soak in 3% hydrogen peroxide solution followed by neutralization and/or dilution of the hydrogen peroxide to 75 ppm or less. The final solution used for storage of a contact lens shall be preserved."
However, to my knowledge, there are no current US government guidelines for disinfection and storage of in-office, reusable hydrogel diagnostic contact lenses. The last CDC recommendation published in 1985 and specifically dealt with HIV contamination (www.cdc.gov).
The ANSI proposal recommends to clean, rinse and initially treat the trial lens with hydrogen peroxide, followed by storage in a multipurpose solution. This may prove adequate assuming that no biofilm has formed in the storage vial and that you replace the multipurpose storage solutions at least monthly. This practice assumes good aseptic techniques and sufficient efficacy and stability of the disinfecting solution over time. Lens storage in chemical disinfectants may result in toxicity or hypersensitivity reactions.
One practical lens reprocessing method guarantees sterility: steam under pressure (autoclave). This process is the standard for hospitals, clinics and dental offices. It eliminates all possible microbial contamination. Auto-claving also provides a reasonable shelf life, thus removing the necessity for monthly storage solution replacement.
In Our Practice
We reprocess all reusable hydrogel contact lenses in the following manner prior to reuse:
1. Digitally clean with Miraflow Daily Cleaner (CIBA Vision).
2. Rinse with non-preserved aerosol saline.
3. Return lens to original vial and fill with non-preserved aerosol saline; seal vial.
4. Autoclave; label with expiration date one year out.
You can reprocess certain high-water content lenses only a limited number of times before they may need replacing. Occasionally a vial will break. All trial lenses require periodic replacement; you should factor this cost in as overhead.
Fortunately, most of our diagnostic lenses are disposable and therefore pose little threat of contamination. Our special needs patients deserve the same level of verifiable safety. And, autoclaves are quite handy for sterilizing forceps, lid speculums and other office equipment.
Mr. Ward is an instructor in ophthalmology at Emory University School of Medicine and Director, Emory Contact Lens Service.