RGP insights

In-Office RGP Lens Disinfection

BY LORETTA B. SZCZOTKA, OD, MS, FAAO
November 2001

When did you last review your procedures for in-office disinfection of RGP diagnostic lenses? Manufacturers of hydrophilic trial lenses post guidelines for disinfection of their products, and autoclaving is still in use in many offices. However, it is difficult to find information specifically on RGP trial lens disinfection, including the types of pathogens targeted for disinfection.

What I Do

The Centers for Disease Control and Prevention (CDC) recommends ophthalmic grade hydrogen peroxide for RGP lenses (see below); therefore I use AOSept, AOSept Clear Care (CIBA Vision) or Ultracare (Allergan) for a five- to 10-minute soak and store them dry. We also clean with Miraflow (CIBA Vision) prior to disinfection and prior to re-insertion during a diagnostic fit. Miraflow is indicated for use as a cleaner for hard (PMMA) lenses, but many reports state its utility for RGP lenses as well. The only precaution for its use on RGP lenses is that prolonged and repeated exposure may cause permanent parameter changes and brittleness from isopropyl alcohol. Use it for no more than 30 seconds and then rinse it off.

Current Standards

In the 2000 American Optometric Association document, "Optometric Clinical Practice Guideline Care of the Contact Lens Patient," the AOA simply states that disinfection of diagnostic contact lenses should be performed by a method approved by the CDC. Searching the CDC Web site (www.cdc.gov) reveals specific guidelines only for the precautions of spreading "HTLV- III/LAV (Human T-Lympho- tropic Virus Type III/Lympha-denopathy) and other microbial pathogens that might be present in tears."

Per its 1985 document (www.cdc.gov/mmwr/prview/mmwrhtml/00000602.htm), the CDC recommends:

Instruments that come into direct contact with external surfaces of the eye should be wiped clean and disinfected by one of the following:

• A five- to 10-minute exposure to a fresh solution of 3% hydrogen peroxide
• A fresh solution containing 5,000 parts per million free available chlorine­a 1/10 dilution of common household bleach (sodium hypochlorite)
• 70% ethanol
• 70% isopropanol. The device should be thoroughly rinsed in tap water and dried.

These procedures were most likely designed for instruments such as tonometer tips which are used repeatedly each day between patients, but some of these regimes may not be appropriate for RGP materials. However, the CDC does make specific recommendations for disinfection of RGP diagnostic lenses between each fitting:

• Disinfect trial hard lenses with a hydrogen peroxide contact lens disinfecting system currently approved for soft contact lenses. RGP lenses may warp if they are heat disinfected.

Recent contact lens textbooks reveal fewer specifics but do provide insight into wet and dry storage. Most studies support storing all lenses dry, including patient spare lenses at home. Because the microbial recovery from dry-stored RGP lenses is minimal and additional rubbing (with a cleaner) and rinsing removes >99 percent of micro-organisms, dry storage is recommended. Furthermore, lens base curve instability from repeated hydration and dehydration does not reach clinically significant levels, even for high Dk materials.

If wet shipping and storage becomes common, new recommendations will be needed by solution manufacturers or the CDC.

Dr. Szczotka is an assistant professor at Case Western Reserve University Dept. of Ophthalmology and Director of the Contact Lens Service at University Hospitals of Cleveland.