contact lens
care
Maintaining
and Disinfecting GP Diagnostic Lenses
BY
MICHAEL A. WARD, MMSC, FAAO
Gas permeable diagnostic
contact lens sets will last for years if you care for and store them properly. Some
trial sets get regular use, while some are used only rarely. Regardless of the frequency
of use, you must be concerned about how you store and care for these lens sets to ensure
cleanliness, parameter accuracy and safety. Figure 1 shows an example of an improperly
stored GP diagnostic lens.
Regularly Check Parameters
Unlike soft lenses, you can accurately verify GP lens parameters
with standard office instrumentation. You can use a magnifying loupe to inspect
lens surfaces and to verify optic zone and overall diameters. A lensometer
can help you check the lens power (for high powers, front vs. back vertex becomes
important) and optical quality. A radiuscope can accurately measure the base curves
and allow you to detect any warpage. However, one thing these instruments can't
tell us is whether the lens surfaces are free from microbial contamination.
Periodically inspect all GP diagnostic lenses to ensure that each
is in its correctly labeled container and that the parameters haven't altered over
time. Replace any warped or out of spec lenses.
Diagnostic Lens Care
Store GP diagnostic lenses wet, in conditioning/storage solution
or dry. Each method offers potential advantages. Lenses stored wet are theoretically
better conditioned for immediate use, whereas lenses stored dry require less maintenance.
Other
considerations exist as well. No contact lens disinfecting solution is approved
for lens storage for greater than 30 days. You must redisinfect lenses that you
store wet in chemical storage/disinfecting/conditioning solutions at least every
30 days. If you don't regularly maintain wet-stored GP lenses, evaporation and aging
may alter the chemical composition of the storage solution, which may compromise
its antimicrobial efficacy.
You must clean and disinfect all diagnostic contact lenses prior
to their reuse. The Centers for Disease Control and Prevention (CDC) recommends
using ophthalmic grade 3% hydrogen peroxide for disinfection of rigid lenses. Specifically,
"Contact lenses used in trial fittings should be disinfected after each fitting
by using a hydrogen peroxide contact lens disinfecting system for 10 minutes."
http://wonder.cdc.gov/wonder/prevguid/p0000318/p0000318.asp).
The two primary peroxide systems available in the United States are Clear Care (CIBA
Vision) and UltraCare (Advanced Medical Optics).
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Figure
1. Improperly stored GP diagnostic contact lens.
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Recommendation
Clean GP diagnostic lenses with an approved surfactant
cleaner such as Boston Advance Cleaner (Bausch & Lomb), Optimum Extra Strength
Cleaner (Lobob Laboratories) or MiraFlow Extra Strength Daily Cleaner (CIBA) after
each use.
Disinfect the lenses with an approved peroxide system (Clear
Care or UltraCare) for a minimum of 10 minutes.
Store rigid diagnostic lenses dry for long-term storage.
Prior to reuse, clean the lenses with an approved cleaner, then
rinse and wet them with an appropriate wetting or conditioning solution. I've followed
this practice for many years and I do not encounter surface wetting problems following
dry storage of GP lenses.
Mr. Ward is an instructor
in ophthalmology at Emory University School of Medicine and Director, Emory Contact
Lens Service.
Contact Lens Spectrum, Issue: September 2006