Wearing contact lenses may change eye bacteria

Wearing contact lenses daily may alter the eye microbiome, according to a new study which may explain why contact lens wearers are at increased risk of certain eye infections.
Researchers at NYU Langone Medical Center in New York City have identified a diverse set of microorganisms in the eyes of daily contact lens wearers that more closely resembles the group of microorganisms of their eyelid skin than the bacterial grouping typically found in the eyes of non-wearers.
The team found that the eye surface, or conjunctiva, had surprisingly higher bacterial diversity than the skin directly beneath the eye in the study's nine contact lens wearers.

They also found three times the usual proportion of Methylobacterium, Lactobacillus, Acinetobacter, and Pseudomonas bacteria in the eyes of the contact lens wearers than is typically found on the surface of the eyeballs of 11 other men and women in the study who did not wear contact lenses.
When measured and plotted on a graph, statistical germ diversity scores showed that the eye microbiome of contact lens wearers had a composition more similar to that of the wearer's skin than the eye microbiome of non-lens wearers.
"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 Maria Gloria Dominguez-Bello.

"What we hope our future experiments will show is whether these changes in the eye microbiome of lens wearers are due to fingers touching the eye, or from the lens's direct pressure affecting and altering the immune system in the eye and what bacteria are suppressed or are allowed to thrive," said Dominguez-Bello.

"These findings should help scientists better understand the longstanding problem of why contact-lens wearers are more prone to eye infections than non-lens wearers," said Dominguez-Bello.
"There has been an increase in the prevalence of corneal ulcers following the introduction of soft contact lenses in the 1970s," said study co-investigator Jack Dodick, professor and chair of ophthalmology at NYU Langone.

"A common pathogen implicated has been Pseudomonas. This study suggests that because the offending organisms seem to emanate from the skin, greater attention should be directed to eyelid and hand hygiene to decrease the incidence of this serious occurrence," he said.