Contact Lenses May Disrupt Eyes' Natural Bacteria
Whether this increases risk for infection isn't clear
By Alan Mozes
TUESDAY, March 22, 2016 (HealthDay News) -- Contact lenses may alter the natural bacterial environment of your eyes, new research suggests.
A small study found that the eye surface of contact lens wearers tends to harbor bacteria normally found on the skin surrounding the eye.
Whether this is caused by finger-to-lens interaction or the actual act of wearing contacts remains unclear. But the findings raise questions as to whether this shift in microbial composition might boost the risk for eye infections, the study authors said.
"Wearing contact lenses is known to increase the risk of microbial keratitis and other inflammatory eye conditions," said study lead author Maria Dominguez-Bello. She is an associate professor with the Human Microbiome Program at New York University School of Medicine, in New York City.
Keratitis is a painful and potentially serious inflammation of the cornea.
More than 30 million Americans wear contact lenses, and the U.S. Centers for Disease Control and Prevention estimates that roughly one in every 500 develops a vision-threatening eye infection each year. Keratitis alone prompts about 1 million doctor and hospital visits annually.
One driver of risk is hygiene. Between 40 percent and 90 percent of contact lens users fail to properly clean and/or regularly replace their contacts as instructed, the CDC says.
Another possible risk factor is the effect contact lenses may have on the bacterial composition of the eye.
The microbiome -- or bacterial community -- of body sites such as the gut, skin and mouth are designed to help resist germs, according to background notes with the study.
However, "despite being important in ophthalmology, the eye microbiome has been largely neglected, and its functions remain unknown," Dominguez-Bello said.
With that in mind, the study team set out to conduct genetic sequencing that compared the eye bacterial community of contact lens wearers and non-lens wearers.
The researchers collected samples from 58 adults, analyzing bacteria on the eye surface, the skin below the eye and on contact lenses from 20 users. Additional samples were taken from 20 participants -- about half of whom wore contact lenses -- at three points over six weeks.