Contact lenses change the bacteria in your eyes to more resemble the microbes found on skin.
A study led by Professor Maria Dominguez-Bello from New York University School of Medicine suggests this alteration may be why contact-lens wearers have a higher risk of eye infections.
According to Yahoo! News, swab samples of conjunctiva, the mucus membrane on the eye surface, and the skin under the eyes were taken from a group of contact-lens wearers, as well as from another group that doesn't wear contacts.
Researchers found the eye surfaces of contact-lens wearers had an increased amount of bacteria associated with skin such as Methylobacterium, Lactobacillus, Acinetobacter and Pseudomonas.
It isn't clear why contact wearers have more of this bacteria, but Dominguez-Bello said the skin bacteria may have been “transferred from the fingers to the lens and to the eye surface."
In a statement, Dominguez-Bello said another possibility is “the lenses exert selective pressures on the eye bacterial community in favor of skin bacteria."
More research is needed to determine whether the new bacteria directly causes eye infections, but the results do encourage contact wearers to keep hygiene in mind when inserting or removing contact lenses.
Previous research showed contact wearers risk the development of numerous inflammatory eye infections such as giant papillary conjunctivitis.
Future studies could determine whether or not the increased amount of infections stem from the eye becoming more vulnerable due to the replacement of its natural bacteria with skin bacteria.
This research was originally published in the journal mBio.