Alterations to the eye microbiome of contact lens wearers may increase infections

Contact lens wearers - ever wondered why you are more likely to experience eye infections than your contacts-less friends? Researchers from NYU Langone Medical Center in New York City think they may have found the answer, in a study that used high-precision genetic tests to map the human microbiome.

Presenting their work at the annual meeting of the American
Society for Microbiology on May 31st in New Orleans, LA, the NYU Langone researchers report that micro-organisms residing in the eyes of people who wear contact lenses daily more closely resemble micro-organisms residing in eyelid skin than the bacteria usually found in the eyes of people who do not wear contacts.

The researchers took hundreds of swabs of different parts of the eye, including the skin directly beneath the eye. Genetic
analysis of swabs and used contact lenses allowed the team to identify which bacteria were present.

Comparing nine contact lens wearers with 11 non-contacts
users, the team found three times the usual proportion of
the bacteria Methylobacterium, Lactobacillus, Acinetobacter and Pseudomonas on the eye surfaces
(conjunctiva) of contact lens wearers than on the eye surfaces of the control group.

Examining the bacterial diversity using a plotted graph, the team observed that the eye microbiome of contact lens wearers is more similar in composition to the microbiome of their skin than the eye microbiome of non-lens wearers.

Interestingly, the researchers say, Staphylococcus bacteria was
found in greater amounts in the eyes of non-lens wearers.
Staphylococcus is linked with eye infections, but is usually
more prominent on the skin. However, the researchers are
unable to explain why non-lens wearers have greater amounts of this bacteria, despite this group traditionally having fewer
eye infections than people who wear contacts.

Next, the team will investigate whether or not changes in the
eye microbiome of people who wear contacts are caused by the
direct pressure of the lens altering the immune system in the eye and hope to identify in greater detail which bacteria thrive or are suppressed in this environment.


Putting a foreign object on the eye 'is not a neutral act'

"Our research clearly shows that putting a foreign object, such
as a contact lens, on the eye is not a neutral act," says senior
study investigator and NYU Langone microbiologist Maria
Gloria Dominguez-Bello, PhD.

"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," she adds.

Last year, Medical News Today looked at a Centers for Disease Control and Prevention (CDC) report on keratitis - a painful eye condition that occurs when the cornea is infected with bacteria, fungi and other microbes - that suggested
improper contact lens care boosts risk of this condition and potentially blindness.