When an outbreak of Fusarium keratitis hit the
In the case of Fusarium, issues involved the chemical composition of ReNu with MoistureLoc multipurpose solution (Bausch & Lomb) combined with inappropriate use by patientsthe creation of the perfect storm.
As of June 30, 2006, there were 164 confirmed cases of Fusarium keratitis in the
A few months later, Advanced Medical Optics voluntarily recalled its Complete MoisturePlus solution due to a threat of Acanthamoeba keratitis (AK). At that time, the CDC estimated that patients with Acanthamoeba were seven times more likely to be using Complete MoisturePlus than another solution.
No doubt, this left many of us in total disbelief, given that the perfect storm is a supposedly a rare occurrence. This situation, however, also helped re-emphasize the importance of proper contact lens care.
As of June 30, 2006, there were 164 confirmed cases of Fusarium keratitis in the United States.
Image courtesy: Ron Melton, O.D., and Randall Thomas, O.D.Higher amounts of Acanthamoeba in the water system may become airborne in the shower and lead to infection.
Image courtesy: Elmer Tu, M.D.
Ecosystem Changes
Disinfection is the core function for a contact lens care system. When the ecosytem changes, however, the care system may not remain as effective.
Take the Acanthamoeba outbreak, for example. One theory: The numbers of Acanthamoeba microbes increased due to changes in water purification and its standards. The higher microbial load may be related to these outside issues.3,4
Another theory behind the rise of infection: aerosolization, in which particles become airborne. Higher amounts of Acanthamoeba in the water system may become airborne in the shower, collect on contact lenses and subsequently cause infection.4
The Fusarium outbreak was traced to ReNu with MoistureLocs polymer package of polyquaternium 10, tetronic and pluronic F127. Also, in a study about the effects of noncompliance, researchers found that by reducing the water content of the solution until a 2x and 4x concentration was achieved vs. the commercial formulation, the evaporative effects of a lens case or bottle being left open were simulated. And, as a result, the formula showed a significant loss in efficacy against Fusarium solani.5
One area of new thinking: As new enhancements are added to the care system (i.e., comfort components), disinfection may become compromised. The scientists responsible for the formultaions did not consider this a problem until the Fusarium and AK outbreaks. The added complexity of the formulation may yield unwanted results. Some companies are leaning toward better disinfection and departing from comfort enhancements.
Lissamine green (left), traditionally used for conjunctival staining, can be used for the cornea as well and stains when there are more severe levels of staining present when compared to fluorescein (center). The cornea will stain with lissamine green if the staining is severe enough (right).
Peroxide Systems
As the Fusarium- and Acanthameoba-related recalls were unfolding, there was much uncertaintyparticularly about the safety and effectiveness of multipurpose solutions in general. There was a move toward other care systems, such as hydrogen peroxide systems.
Peroxide has a longer history in contact lens care than any of the multipurpose solutions. Unexplained discomfort, irritation, redness and dryness all seem to be alleviated with hydrogen peroxide-based systems.
But, there are certainly pitfalls with such care regimens, such as long-term storage (neutralized peroxide is unpreserved), chemical burns and more complex disinfection. Despite the disadvantages, however, peroxide is useful in cases of discomfort, irritation, redness and dryness.
Compliance Conundrum
Both outbreaks emphasized the importance of compliance with a contact lens care regimen. Poor compliance has been a factor (sometimes large, sometimes small) in many infections, including Fusarium and Acanthamoeba. The Fusarium outbreak was linked to topping off (solution re-use), unclean cases and evaporation. The Acanthameoba outbreak was tied to solution re-use, not rubbing and infrequent case replacement.4
Adherence to regimen has always been a difficult area for the clinician and patient. Philip Morgan, MCOptom, Ph.D., asked a series of 14 questions on contact lens care steps for 1,402 lens wearers (See Compliance Questions for Contact Lens Patients). He found that only 0.3% of the wearers were fully compliant with all steps.6
Compliance Questions for Contact Lens Patients Answers to the following questions may tell you how well your patients comply with contact lens wear and care: For daily wear patients: Do you sleep overnight and/or nap in your lenses? For extended-wear patients: How often do you sleep in your lenses? Do you wash your hands before inserting and removing lenses? What type of soap do you use? What do you use to clean/store your contact lenses? Where do you store your contact lenses? Do you replace your solution or top it off? Do you cover your contact lens completely with solution? Do you close your lens case tightly? Do you clean your case? How often? How often do you change your case? Do you close the cap of your bottle tightly? Do you check the expiration dates on your bottles? Do you ever share your contact lens case with other people? Source: Morgan P. Contact lens compliance and reducing the risk of keratitis. Available at: www.siliconehydrogels.org/editorials/index.asp (Accessed March 14, 2008).
Lack of compliance with rub-and-rinse regimens led manufacturers to develop no-rub solutions that would surpass FDA requirements for kill rates. The idea was that by simplifying the care regimen, compliance would increase.7
How many days do you wear your lenses before discarding them?
Since the outbreaks, however, there has been renewed emphasis on rubbing and rinsing. More than 70% of eye-care professionals recommend rubbing over no-rub, according to market research conducted by Penn Schoen & Berland Associates in September 2006.
Dr. Morgan states that inadequate surfactant cleaning accounts for a threefold increase in the risk of infection.6 Rubbing and rinsing helps provide a safety net against infection.8
Another consideration: Silicone hydrogel lenses tend to accumulate more deposits than lenses made of other materials. In one study, however, the addition of a rub-and-rinse step significantly reduced deposition rates in the tested silicone hydrogels.9
Staining
One vital dye I have been using extensively for evaluating contact lens patients has been lissamine green. Fluorescein dye is more commonly used for contact lens work. One study has shown there is more conjunctival (fluorescein and lissamine green) staining with some silicone hydrogel lenses compared to others.10
Lissamine green, traditionally used for conjunctival staining, stains the cornea as well.11 I believe that lissamine green stains when there are more severe levels of staining present when compared to fluorescein.11 My own clinical data show that the mean grade of lissamine green staining was always lower than the mean grade of fluorescein staining on the conjunctiva across six zones (p<.0001).10
With respect to corneal staining, lissamine green behaves the same way. The cornea will stain with lissamine green if the staining is severe enough. I think if lissamine green staining is present, then it would be more indicative of a problem that needs clinical intervention.
In the aftermath of the storms, I still prescribe and heartily recommend contact lenses and all approved care systems for my patients. But, its also important that we pay attention to patients contact lens habitsand prescribe lenses along with a thorough education and discussion of care regimens.
Dr. Hom is the author of Manual of Contact Lens Prescribing and Fitting with CD-ROM, 3rd ed. (Elsevier, 2006), and is in private practice in
1. Henderson D. Firm halts contact lens solution sales.
2. Perfect storm. Available at http://en.wikipedia.org/wiki/Perfect_storm (Accessed December 13, 2007).
3. Joslin CE, Tu EY, McMahon TT, et al. Epidemiological characteristics of a Chicago-area Acanthamoeba keratitis outbreak. Am J Ophthalmol 2006 Aug;142:2127.
4. Joslin CE, Tu EY, Shoff ME. et.al. The association of contact lens solution use and Acanthamoeba keratitis. Am J Ophthalmol 2007 Aug;144(2):169-80.
5. Barr JT. Fusarium keratits: special report. Available at: www.clspectrum.com/article.aspxarticle=13117 2006 Sep (accessed March 25, 2008).
6. Morgan P. Contact lens compliance and reducing the risk of keratitis. Available at: www.siliconehydrogels.org/editorials/index.asp (Accessed March 14, 2008).
7. Compliance (medicine). Available at: http://en.wikipedia.org/wiki/Compliance_%28medicine%29 (Accessed March 19, 2008).
8. Hom MM. Improving contact lens compliance. Rev Optom 2007 Sep;144(9):44-7.
9. Nichols JJ. Deposition rates and lens care influence on galyfilcon A silicone hydrogel lenses. Optom Vis Sci 2006 Oct;83(10):751-7.
10. Hom MM. A comparison of conjunctival staining with fluorescein and lissamine green between lotrafilcon b and galyfilcon Poster presentation at
11. Smick K: Personal communication.
