According to a study published in the November issue of Archives
of Ophthalmology, a contact lens solution that was implicated
in an epidemic of the eye infection Fusarium
keratitis between 2004 and 2006 was likely due to a reduction in the
solution’s antifungal activity because of exposure to prolonged
temperature increase.
In August 2004, Bausch & Lomb
introduced the product ReNu with MoistureLoc, a contact lens
solution that contains a unique antimicrobial agent. The solution was
associated with cases of Fusarium
keratitis, according to
U.S. government reports, since March 2006. Eventually there were 154
confirmed cases identified in the United States of this condition
characterized by inflammation of the cornea (keratitis). “Bausch
&
Lomb investigators acknowledged that all original cases appear to be
related to ReNu with MoistureLoc produced in their Greenville, S.C.,
plant.” write John D. Bullock, M.D., M.P.H., M.Sc. (Wright State
University Boonshoft School of Medicine, Dayton, Ohio) and colleagues.
The
Food and Drug Administration (FDA) inspected the Greenville facility in
2006 and cited Bausch & Lomb for poorly controlling temperature
in
the production, storage and transport of products from this plant.
Bullock and colleagues further studied the effects of temperature on
the growth of the Fusarium fungus by analyzing five
contact
solutions in addition to ReNu with MoistureLoc. The researchers explain
that, “Two bottles of each solution were separately stored at room
temperature and 60 degrees Celsius [140 degrees Fahrenheit] for four
weeks, serially diluted and then tested for their ability to inhibit
growth of 11 Fusarium isolates (seven of which were
associated with the keratitis epidemic).”
ReNu
with MoistureLoc showed the greatest decline in anti-fungal activity
after the 60-degree storage period, while Clear Care and ReNu MultiPlus
demonstrated the smallest decline. The authors also specifically
analyzed the strains of Fusarium that were linked
to the
keratitis epidemic. The found that when stored at room
temperature, ReNu with MoistureLoc allowed fungal growth in
27 of
84 different blends of isolates grown in different solutions
and
at different levels of dilution. When stored at 140 degrees Farenheit,
the solution allowed fungal growth in 67 of 84 of these combinations.
“The
precise temperature, duration of exposure to elevated temperature and
extent of temperature fluctuation that may diminish the antimicrobial
activity of a particular contact lens solution is not known, and thus,
additional studies may be warranted. However, our findings, coupled
with the FDA reports of Bausch & Lomb’s failure to regulate the
storage and transport temperatures of the products manufactured in
their Greenville plant, may be significant,” conclude Bullock and
colleagues.
“Knowledge of the potential loss of antimicrobial
activity of contact lens solutions and other pharmaceutical products
when exposed to higher temperatures and the risk of such exposure when
storing and transporting those products may help prevent such epidemics
in the future.”
Temperature Instability of ReNu With MoistureLoc: A New Theory
to Explain the Worldwide Fusarium Keratitis Epidemic of 2004-2006
John D. Bullock; Ronald E. Warwar; B. Laurel Elder; William I. Northern
Archives of Ophthalmology (2008).
126[11]: pp. 1493-1498.
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