Millions of people around the world wear contact lenses, with 24 million wearers in the U.S. alone. While contact lens care is generally very safe, lenses that are not properly cleaned and disinfected increase the risk of severe eye infection. Any lens that is removed from the eye needs to be cleaned and disinfected before it is reinserted.
Care of contact lenses includes cleaning the storage case, since it is a potential source of infection.
Assaf Kratz, MD, and Tova Lifshitz, MD, of Soroka University Medical Center in Israel, and their colleagues studied the rate of contamination in contact lens storage cases by taking samples of the contact lens disinfection solution from lens cases belonging to candidates for refractive surgery. Thirty storage cases of 16 asymptomatic candidates were tested for the study. In two-thirds of the storage cases, at least one pathogen was detected.
The most common pathogen was Pseudomonas (41.2 percent), a known cause of severe corneal infections. Fungal pathogens were found in 3.3 percent of the cases. Pathogens were found in all of the types of storage solutions that were studied; some solutions tested positive for pathogens every time they were tested among the samples. The pathogens can cause keratitis, an often painful inflammation of the cornea; complications from keratitis can lead to vision loss.
"The picture that arises from this study is disturbing," the authors conclude. "It seems that the commonly used disinfecting solutions provide little protection from contamination of contact lens storage cases." The authors urge contact lens wearers to closely adhere to contact lens care guidelines, including frequent cleaning and replacing their lens case regularly, in order to prevent contamination.
This research was presented at the 2008 Joint Meeting of the American Academy of Ophthalmology (Academy) and European Society of Ophthalmology (SOE) in Atlanta, Georgia, U.S. on November 10, 2008.
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