<span id="midArticle_start"/><span id="midArticle_0"/>(Reuters Health) - People who wear contact lenses have different microorganisms living on the surface of their eyeballs than those who do not, according to new research.
<span id="midArticle_1"/>
<span id="midArticle_2"/>That may explain why contact wearers tend to have more eye infections, the researchers reported at the annual meeting of the American Society for Microbiology on May 31 in New Orleans.
<span id="midArticle_3"/>
<span id="midArticle_4"/>“As other body sites such as gut, skin and mouth, the eye has a normal community of bacteria, expected to confer resistance to invaders,” said senior author Maria G. Dominguez-Bello of New York University School of Medicine.
<span id="midArticle_5"/>
<span id="midArticle_6"/>“Despite being important in ophthalmology, the eye microbiome has been largely neglected, and its functions remain unknown,” Dominguez-Bello told Reuters Health in a statement.
<span id="midArticle_7"/>
<span id="midArticle_8"/>The researchers swabbed various parts of the eyes, including the eyeball surface and the skin directly beneath the eye, of nine contact lens wearers and 11 non-lens wearers at three different times. They used so-called metagenomic sequencing to identify the specific microorganisms in each swab.
<span id="midArticle_9"/>
<span id="midArticle_10"/>For contact wearers, the bacterial population living on the eyeball surface was more similar to that of the eyelid skin than for non-lens wearers, the researchers found. Contacts may transfer bacteria from the finger skin to the eye surface, they write in their poster presentation.
<span id="midArticle_11"/>
<span id="midArticle_12"/> <span class="first-article-divide"/>For both groups, there were more than 5,000 bacterial strains on the eye surface and more than 2,000 strains on the skin directly beneath the eye.
<span id="midArticle_13"/>
<span id="midArticle_14"/>This was unexpected, since tears contain antibacterial compounds, Dominguez-Bello said.
<span id="midArticle_15"/>
<span id="midArticle_0"/>Non-lens wearers tended to have more bacterial strains than lens wearers in each location.
<span id="midArticle_1"/>
<span id="midArticle_2"/>But for lens wearers the proportion of bacteria from the Methylobacterium, Lactobacillus, Acinetobacter and Pseudomonas families was three times as great as for non-lens wearers.
<span id="midArticle_3"/> <span class="second-article-divide"/>
<span id="midArticle_4"/>“The findings indicate there are significant differences in diversity of bacterial sequences between contact and non-contact lens wearing subjects and that taxonomic units in the contact lens wearing group were more like the skin than the normal eye,” said Dr. Stephen Pflugfelder, who studies cornea and ocular surface diseases at Baylor College of Medicine in Houston, Texas.
<span id="midArticle_5"/>
<span id="midArticle_6"/>“Because they did not perform cultures, the study didn't determine if these sequences were from live viable bacteria or dead bacteria that may have been transmitted by the finger skin,” Pflugfelder, who was not part of the new research, told Reuters Health by email.
<span id="midArticle_7"/>
<span id="midArticle_8"/>Previous studies have shown that the eye is very sparsely colonized by microbes compared to other areas of the body like the mouth, according to Mark Willcox, the Brien Holden Vision Chair in Experimental Optometry at the University of New South Wales in Sydney, Australia.
<span id="midArticle_9"/> <span class="third-article-divide"/>
<span id="midArticle_10"/>“So, it seems unlikely that the ocular microbiota plays a large part in protecting the eye from colonization by potential pathogens,” Willcox, who was not involved in the research, told Reuters Health by email.
<span id="midArticle_11"/>
<span id="midArticle_12"/>Contact lens wearers are at about 80 times greater risk for corneal infection, or keratitis, than those who do not wear lenses, he said.
<span id="midArticle_13"/>
<span id="midArticle_14"/>Pseudomonas, which was three times as common among lens wearers in the new research, is most often responsible for lens wearers’ keratitis, he said.
<span id="midArticle_15"/>
<span id="midArticle_0"/>Disinfecting the lenses when not being worn and washing hands with soap and water and drying them prior to touching the lenses reduces infection risk, he said.
<span id="midArticle_1"/>
<span id="midArticle_2"/>Further studies will need to determine if these bacteria are transferred from the fingers to the lens and to the conjunctiva, or if the lenses act to favor skin-like bacteria in the eye microbiota, Dominguez-Bello said.
<span id="midArticle_3"/>
<span id="midArticle_4"/>“It’s too early to give advice yet, but the results start to indicate why contact lens wearers are more prone to have eye infections than non wearers,” she said.
<span id="midArticle_5"/>
<span id="midArticle_1"/>
<span id="midArticle_2"/>That may explain why contact wearers tend to have more eye infections, the researchers reported at the annual meeting of the American Society for Microbiology on May 31 in New Orleans.
<span id="midArticle_3"/>
<span id="midArticle_4"/>“As other body sites such as gut, skin and mouth, the eye has a normal community of bacteria, expected to confer resistance to invaders,” said senior author Maria G. Dominguez-Bello of New York University School of Medicine.
<span id="midArticle_5"/>
<span id="midArticle_6"/>“Despite being important in ophthalmology, the eye microbiome has been largely neglected, and its functions remain unknown,” Dominguez-Bello told Reuters Health in a statement.
<span id="midArticle_7"/>
<span id="midArticle_8"/>The researchers swabbed various parts of the eyes, including the eyeball surface and the skin directly beneath the eye, of nine contact lens wearers and 11 non-lens wearers at three different times. They used so-called metagenomic sequencing to identify the specific microorganisms in each swab.
<span id="midArticle_9"/>
<span id="midArticle_10"/>For contact wearers, the bacterial population living on the eyeball surface was more similar to that of the eyelid skin than for non-lens wearers, the researchers found. Contacts may transfer bacteria from the finger skin to the eye surface, they write in their poster presentation.
<span id="midArticle_11"/>
<span id="midArticle_12"/> <span class="first-article-divide"/>For both groups, there were more than 5,000 bacterial strains on the eye surface and more than 2,000 strains on the skin directly beneath the eye.
<span id="midArticle_13"/>
<span id="midArticle_14"/>This was unexpected, since tears contain antibacterial compounds, Dominguez-Bello said.
<span id="midArticle_15"/>
<span id="midArticle_0"/>Non-lens wearers tended to have more bacterial strains than lens wearers in each location.
<span id="midArticle_1"/>
<span id="midArticle_2"/>But for lens wearers the proportion of bacteria from the Methylobacterium, Lactobacillus, Acinetobacter and Pseudomonas families was three times as great as for non-lens wearers.
<span id="midArticle_3"/> <span class="second-article-divide"/>
<span id="midArticle_4"/>“The findings indicate there are significant differences in diversity of bacterial sequences between contact and non-contact lens wearing subjects and that taxonomic units in the contact lens wearing group were more like the skin than the normal eye,” said Dr. Stephen Pflugfelder, who studies cornea and ocular surface diseases at Baylor College of Medicine in Houston, Texas.
<span id="midArticle_5"/>
<span id="midArticle_6"/>“Because they did not perform cultures, the study didn't determine if these sequences were from live viable bacteria or dead bacteria that may have been transmitted by the finger skin,” Pflugfelder, who was not part of the new research, told Reuters Health by email.
<span id="midArticle_7"/>
<span id="midArticle_8"/>Previous studies have shown that the eye is very sparsely colonized by microbes compared to other areas of the body like the mouth, according to Mark Willcox, the Brien Holden Vision Chair in Experimental Optometry at the University of New South Wales in Sydney, Australia.
<span id="midArticle_9"/> <span class="third-article-divide"/>
<span id="midArticle_10"/>“So, it seems unlikely that the ocular microbiota plays a large part in protecting the eye from colonization by potential pathogens,” Willcox, who was not involved in the research, told Reuters Health by email.
<span id="midArticle_11"/>
<span id="midArticle_12"/>Contact lens wearers are at about 80 times greater risk for corneal infection, or keratitis, than those who do not wear lenses, he said.
<span id="midArticle_13"/>
<span id="midArticle_14"/>Pseudomonas, which was three times as common among lens wearers in the new research, is most often responsible for lens wearers’ keratitis, he said.
<span id="midArticle_15"/>
<span id="midArticle_0"/>Disinfecting the lenses when not being worn and washing hands with soap and water and drying them prior to touching the lenses reduces infection risk, he said.
<span id="midArticle_1"/>
<span id="midArticle_2"/>Further studies will need to determine if these bacteria are transferred from the fingers to the lens and to the conjunctiva, or if the lenses act to favor skin-like bacteria in the eye microbiota, Dominguez-Bello said.
<span id="midArticle_3"/>
<span id="midArticle_4"/>“It’s too early to give advice yet, but the results start to indicate why contact lens wearers are more prone to have eye infections than non wearers,” she said.
<span id="midArticle_5"/>
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