Wearing Contacts May Influence What Kind of Bacteria, Including Those That Cause Infection, Call Your Eye Home

Contact Lens
Contact lenses may create a better home for certain microbes, including some known to cause infection, in the eye. Photo Courtesy of Shutterstock

Most any modern-day convenience comes with its drawbacks, whether it’s frantically checking your pockets for a phantom vibrating text you were sure just happened to losing the concept of time during a six-hour marathon of Breaking Bad.

For contact lens wearers, that drawback has been an increased risk of eye injection. Nearly one million Americans visit the doctor or emergency room because of an eye infection annually, resulting in $175 million of direct medical costs, according to the Centers for Disease Control and Prevention. Though not all these infections are linked to the use of contact lenses, it’s estimated that up to one in every 500 wearers suffer from it every year. These infections are largely tied to the improper cleaning or wearing of contacts – leaving them on for too long or while sleeping for instance.

But where exactly the germs responsible for these infections come from in the first place is somewhat a mystery. Now, researchers from the NYU Langone Medical Center claim they may have shined a light on that question. In a small pilot study to be presented at the annual conference for the American Society for Microbiology in New Orleans, they swabbed the eyes of nine contact lens wearers and 11 non-lens wearers. They then analyzed the microbial environments, or microbiomes, of the contact lens wearers’ eye surfaces as well as the skin underneath their eyes and compared it to those of the control group. They found that the microbiomes of contact lens wearers were noticeably different from the controls, with the former containing a greater proportion of certain bacterial species known to trigger eye infections.

Analyzing the genetic diversity of bacteria on the eye surface, or conjunctiva, in contact lens wearers, the authors found that it strikingly resembled that of the skin under the eye. Compared to the control group, the conjunctiva had relatively higher amounts of bacteria belonging to the Methylobacterium, Lactobacillus, Acinetobacter, and Pseudomonas genus, though only Pseudomonas and very occasionally Acinetobacter are regularly linked to eye infections. "Our research clearly shows that putting a foreign object, such as a contact lens, on the eye is not a neutral act," said senior study investigator and NYU Langone microbiologist Dr. Maria Gloria Dominguez-Bello in a press release.

The authors exercise patience about what their study necessarily means, though. "Our results do not show causation, but association," Dominguez-Bello told Medical Daily. It might be the case that these bacteria are transferred to the contact lens via the skin on our fingers, but perhaps the microbiome is influenced by the pressure of the lens on the eye, allowing for different species of bacteria to flourish, Dominguez-Bello notes. In fact, while Pseudomonas was more prevalent among lens wearers, another genus of bacteria known to cause eye infections, Staphylococcus, wasn’t, which the researchers didn’t anticipate. "Further research needs to show that the contact lens eye bacterial community pattern is less resistant to injections," she told Medical Daily.

Still, while it might take some time to figure how lens wearers are more susceptible to infection, we do know that they are at higher risk. A risk that can be significantly lowered by following these simple tips, as per the CDC:

  • Wash your hands with soap and water. Dry them well with a clean cloth before touching your contact lenses every time.

  • Don't sleep in your contact lenses unless prescribed by your eye doctor.

  • Keep water away from your contact lenses. Avoid showering in contact lenses, and remove them before using a hot tub or swimming.

Source: Shin H, Catalano D, Price K, et al. Microbiota on Human Eyes Differ Between Contact Lens Wearers and Non-Lens Wearers. American Society for Microbiology Conference. 2015.

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