Travelers, Contact Lenses, and Keratitis
Travelers, Contact Lenses, and Keratitis
Abstract & Commentary
Synopsis: Bacterial eye infections can complicate travel for individuals using contact lenses. In Hong Kong, keratitis was linked to the use of tap water to store lenses, a failure to air-dry lens storage cases, and the use of hydrogen peroxide as a disinfectant.
Source: Houang E, et al. Microbial keratitis in Hong Kong: Relationship to climate, environment and contact-lens disinfection. Trans R Soc Trop Med Hyg. 2001;95:361-367.
During 18 months between 1997 and 1998, 223 cases of ulcerative keratitis were identified in Hong Kong. As some patients had received previous antimicrobial therapy, only one third had positive cultures. Pseudomonas, a relatively common cause of keratitis in the tropics, was the most common etiologic agent isolated in both users and nonusers of contact lenses. A variety of other bacteria were also identified as were some fungi and the protozoa, Acanthamoeba. Other studies have suggested that fungi are relatively more common in equatorial tropical areas. Antimicrobial susceptibility testing in Hong Kong suggests that a quinolone antibiotic would provide excellent coverage for most of the bacterial organisms causing keratitis.
Uninfected contact lens users were also recruited as part of a case-control study. As compared to controls, contact lens users with keratitis were more likely to use a one-step hydrogen peroxide disinfection regimen, to store their lenses overnight in tap water, and not to air-dry their empty storage cases.
Contact lens storage containers were also cultured. Bacterial growth was less likely if the storage containers were disinfected with a multipurpose solution than if they were disinfected with hydrogen peroxide. The multipurpose solutions contained both a cleanser and a disinfectant, were inexpensive and available commercially.
Comment by Philip R. Fischer, MD, DTM&H
Travelers with contact lenses often experience discomfort and hassle during long airplane trips and while traversing time zones. In a 1999 review of "sore eyes and travelers," Peter Leggat and his Australian colleagues provided good counsel in reminding travelers to use regular glasses instead of contact lenses during long air trips. When contact lenses must be used, regular lens cleaning and ocular application of lubricating drops can help.1
This new study from Hong Kong provides sound epidemiologic evidence to guide the practical use of contact lenses, especially in humid tropical areas. It is wise to use a proven cleaning solution, clean lens storage, and, in the event of infection, a good antimicrobial agent.
There have been recommendations that hydrogen peroxide be used for cleaning lenses, but this study, as well as an earlier review,2 demonstrates that hydrogen peroxide is not totally effective for this purpose. Use of commercial preparations containing both a cleanser and a disinfectant seems to be advisable. Realizing that supplies and quality might vary in different parts of the world, travelers should carry an adequate amount of a multipurpose solution.
This study from Hong Kong shows that lens storage affects the risk of infection. While the use of tap water to clean lenses did not vary between infected patients and controls, patients were more likely to use tap water for overnight storage of lenses. Multipurpose solutions (containing both a cleanser and a disinfectant) can effectively be used for overnight lens storage. In addition, storage containers should be air dried between uses to prevent the overgrowth of pathogens, especially protozoa such as Acanthamoeba. If hydrogen peroxide is used to clean containers, the containers should have at least 2 hours of contact with the solution.2
The medical kit for travelers should include a topical antibiotic for presumptive use in the event of infection. The Hong Kong study confirms that a quinolone, such as ciprofloxacin, is a reasonable choice for a traveler’s medical kit.
References
1. Leggat PA, Speare R, Moon MEL. Sore eyes and travelers. J Travel Med. 1999;6:45-47.
2. Holden B. A report card on hydrogen peroxide for contact lens disinfection. CLAO J. 1990;16:S61-S64.
Dr. Fischer, Professor of Pediatrics, Department of Pediatric & Adolescent Medicine, Mayo Clinic, Rochester, MN, is Associate Editor of Travel Medicine Advisor.
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