Eye Infection Epidemic Traced To Reduced Antifungal Properties Of Contact Lens Solution In High Temperatures

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Main Category: Eye Health / Blindness
Also Included In: Infectious Diseases / Bacteria / Viruses;  Biology / Biochemistry
Article Date: 12 Nov 2008 - 0:00 PST

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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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