Anyone who wears contact lenses knows that proper storage and disinfection is key to keeping eyes healthy. But new research shows that even those who practice proper cleaning techniques may be more at risk for harmful bacteria than previously believed.

Researchers from Israel found at least one dangerous pathogen in two-thirds of the thirty storage cases they tested. The most common type found was Pseudomonas [sue-doh-moan-as], which is known to cause severe corneal infections. The researchers also found fungal pathogens during their tests.

Both types of pathogens can lead to a disease called keratitis [care-ah-TIE-tiss], a swelling of the cornea that is frequently painful. Complications from the disease can cause vision loss.

The results were alarming because all the test subjects used disinfecting solutions to store their lenses, which shows these solutions may not be an effective barrier against disease.

According to the American Academy of Ophthalmology, more than twenty-four million Americans use contact lenses. If the lenses aren’t properly cleaned and stored, users face an increased risk of infection, corneal ulcers and even blindness.

So what can contact lens wearers do? To guard against contamination, doctors advise thoroughly cleaning any lens that is removed from the eye. The U-S Food and Drug Administration also recommends replacing the lenses frequently and undergoing eye examinations at least once a year. And don’t forget to clean the storage case… that can be a potential source of contamination, too, doctors warn.