The U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) are alerting healthcare professionals and their patients who wear soft contact lenses to an increasing number of reports in the United States of rare but serious fungal infections in the eye that can cause permanent loss of sight. Some patients have reported a significant loss of vision, resulting in the need for a corneal transplant.
A fungus called Fusarium has been identified as the cause of the reported infections. As of April 9, 2006, 109 cases of suspected Fusarium keratitis are under investigation by CDC and public health authorities in 17 states of the U.S.
"This is a serious infection and soft contact lens users should be mindful of the potential to develop this problem," said Dr. Daniel Schultz, director of the FDA's Center for Devices and Radiological Health. "We're advising consumers to practice good basic hygiene and follow manufacturers' instructions for proper use, cleaning and storage of their lenses, and report any signs of infection to their doctors."
Clinicians who evaluate patients with microbial keratitis should consider that a fungal infection may be involved and refer the patient to an ophthalmologist, if appropriate to obtain a specimen for laboratory analysis. In addition, the FDA and CDC are urgently advising consumers to take precautions to prevent contamination of the soft lenses and the products used to maintain them. These preventive practices for contact lens wearers include the following:
-- Wash hands with soap and water, and dry (lint-free method) before handling lenses.
-- Wear and replace lenses according to the schedule prescribed by the doctor.
-- Follow the specific lens cleaning and storage guidelines from the doctor and the solution manufacturer.
-- Keep the contact lens case clean and replace every three to six Â months.
-- Remove the lenses and consult your doctor immediately if you experience symptoms such as redness, pain, tearing, increased light sensitivity, blurry vision, discharge or swelling.
-- In addition, regardless of which cleaning/disinfecting solution used, wearers may want to consider performing a "rub and rinse" lens cleaning method, rather than a no-rub method, in order to minimize the number of germs and reduce the chances of infection.
Of the 30 patient cases fully investigated so far, 28 wore soft contact lenses and two reported no contact lens use. Twenty-six of the soft contact lens users who remembered which solution they used during the month prior to the infection onset reported using a Bausch & Lomb ReNu brand contact lens solution or a generic brand manufactured by the same company. Five case-patients reported using other solutions in addition to the ReNu brand, and nine patients reported wearing contact lenses overnight, a known risk factor for microbial keratitis.
"It is important to note that some of the affected patients had used other solutions in addition to the ReNu brand, and that the source of this fungus has not yet been identified. But we're working with CDC and Bausch & Lomb -- and we're investigating other possible causes -- to prevent these infections," Schultz added.
Bausch and Lomb has informed FDA that they are voluntarily stopping shipment of the ReNu Moisture Loc product while they are continuing to investigate the cause of these infections. Soft contact lens users who have existing supplies of the Renu Moisture Loc should use the product with caution and report any signs and symptoms of eye infection to their doctors.
Clusters of Fusarium keratitis were reported among contact lens users in Asia beginning in November 2005. In February 2006, Bausch & Lomb voluntarily suspended sales of its ReNu multipurpose solutions in Singapore and Hong Kong after multiple reports of the infection among contact lens users there. No other jurisdictions have taken similar action to date.
Fusarium species are normally found in many plants, soil, and tap water. The annual risk of contact lens-related microbial keratitis is estimated in most studies to be between four and 21 per 10,000 patients, depending on whether the lenses are worn only during the day or continuously overnight.
Fungal keratitis can be associated with trauma to the surface of the eye, immunodeficiencies, and contact lens use. Organisms associated with contact lens-related keratitis are usually bacteria rather than fungus, often arising from contamination of lens care products or from contact lens storage cases.