Accumulation of bacteria on the surface of contact lenses is a major cause of contact lens-related eye infections. The key to preventing this buildup is disrupting the formation of biofilms in contact lens deposits, according to a new study.
By breaking apart the structure of biofilms — complex formations of microorganisms that excrete a protective and adhesive matrix on the surface of contact lenses during wear — researchers have found that the bacteria on the lens become much more susceptible to disinfection with contact lens solutions.
“Infections by the bacteria Pseudomonas aeruginosa can cause severe scarring and vision loss when they spread to the cornea,” said study author Jerry Nick, MD, associate professor of medicine at National Jewish Health. “By breaking apart a molecular scaffolding that encases the organisms and makes them more difficult to eradicate, we were able to significantly reduce bacterial infection of the cornea.”
The eye normally fights infections through a variety of defense mechanisms including blinking, which helps remove bacterial organisms from the surface of the eye. Contact lens wear, however, reduces the frequency and effectiveness of blinking, and bacteria can more easily adhere to the surface of the contact lens, according to the study authors.
If those bacteria infect the corneal surface, they can destroy the delicate corneal cells, which can lead to scarring and vision loss. The condition — known as microbial keratitis — affects about two to four contact lens wearers per 10,000 each year, the researchers said.
Dr. Nick and his colleagues confirmed earlier findings that cellular debris from immune cells that fight eye infections actually provide raw materials for biofilm formation on contact lenses. By using a special enzyme (DNAase) combined with another compound, the researchers were able to break down the chemical bonds of these elements that support contact lens biofilms.
The treatment reduced biofilms on the contact lenses by 79.2 percent. The same treatment reduced corneal infections in animals by 41 percent. There was no evidence of any harm caused by the treatments.
“These are very promising early results that point to potentially new methods for removing bacterial biofilms from contact lens surfaces, thereby reducing the risk of microbial keratitis,” said study author Danielle Robertson, OD, PhD, assistant professor of ophthalmology at UT Southwestern.
The results of the study were recently published online by the journal Investigative Ophthalmology and Visual Science.