What to Know About Contact Lenses and Infections

Our bodies are home to billions of microbes of all types. Microorganisms find our bodies quite comfortable, and we have a normal flora of bacteria, fungi, and viruses that, for the most part, enhance our quality of life and health. Sometimes, though, bacterial overgrowth or an invasion of a virus that our bodies don’t particularly like create infections that can be threatening to our life and can be harmful to our vision and eye health.

Woman using a mirror to insert a contact lens
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We have known for quite some time that contact lens wearers have about 15 times higher risk of getting eye infections than non-contact lens wearers. Besides manipulation of the lens with our fingers, researchers were not always clear on how the bacterial environment in the eye changes when wearing contact lenses. However, researchers at NYU completed a study that was displayed at the annual meeting of the American Society for Microbiology in May 2015 that shed some light on differences in the types and amounts of microorganisms that may be present in contact lens wearers versus non-contact lens wearers.

Bacterial Study

Hundreds of swabs of different parts of the eye were taken during the study. Analysis of these swabs allowed the team to study what types of bacteria were present. The study included 20 people. Nine of the participants wore contact lenses and the remaining did not. The scientists took hundreds of swabs of the skin around the eye, parts of the eye itself and even used contact lenses. These swabs were analyzed in a laboratory to count how many different bacteria were present in the eye.

After analyzing the results, the researchers found three times the usual number of bacteria Methylobacterium, Lactobacillus, Acinetobacter and Pseudomonas on the eyes of contact lens wearers. They pointed out that the eye microbiome resembled the microbiome of the skin rather than that of the normal eye. This information could be important in helping scientists understand why contact lens wearers are more susceptible to eye infections than non-contact lens wearers. It may also help scientists determine if the increase in eye infections in people wearing contact lenses is due to fingers touching the eye or from contact lenses directly contacting the eye.

However, the researchers pointed out something they did not expect to find. While the eye microbiome in contact lens wearers included some potentially hazardous bacteria that we find more commonly on our skin, the study did show that 5,245 different strains of bacteria and subtypes were found in the eye of contact lens wearers. Also, 2,133 strains were found on the skin directly beneath the contact lens wearers, while 3,839 different strains were found on non-contact lens wearers. Interestingly, researchers also counted more Staphylococcus bacteria, which are also associated with eye infections and present in high amounts on our skin, in the eyes on non-contact lens wearers. They admitted it was puzzling to see this disparity. In summary, contact lens wearers had fewer bacteria, but the type of bacteria found could potentially be more hazardous to eye health.

Tips to Prevent Infection

As with all studies, more research is needed to clarify the data. However, it does reinforce the fact that contact lens wearers should pay particular attention to their eye and hand hygiene. One can easily lower the risk for infection by the following:

  • Wash your hands with soap and water. Dry your hands completely before touching your contact lenses.
  • Even if you've been prescribed a lens that is FDA-approved to sleep in, you are still at higher risk for an eye infection. Make sure you to follow your healthcare provider's schedule and even limit the number of days you sleep in contact lenses. Even better, switch to a daily wear-only schedule instead.
  • Avoid swimming, showering, and using hot tubs with contact lenses in. Some types of water may contain microbes that can attach themselves to your contact lens and then eat away at your cornea. This type of infection, called Acanthaomeba, can cause permanent vision loss.
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  • 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.

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.