Bacteria and ‘dry eye’: what’s the connection? FB Twitter LinkedIn

Bacteria and ‘dry eye’: what’s the connection?

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Sydney, Australia, 19 December 2016: ‘Dry eye’ causes discomfort for millions of people worldwide – itching, redness, pain and blurred vision are all symptoms of it. Over $1 billion is spent each year by people on artificial tears to combat it but it could be bacteria that are the key to unlocking the mystery of dry eye and developing better treatments.

While tiny glands in our eyelids (known as meibomian glands) secrete a substance (meibum) to protect and prevent our eyes from drying out, when they aren’t functioning properly ‘dry eye’ can be the result. In fact, meibomian gland dysfunction (MGD) is the leading cause of dry eye.

Researchers at Brien Holden Vision Institute are now homing in on the microbial community that inhabits the eye’s surface, the ‘ocular microbiome’, to determine if it plays a role in the development of MGD. They figure that a change to the balance of this ‘commensal’ community may lead to eyelid inflammation, changes to the composition of the eye’s tears or to the quality of meibum produced by the gland.

The researchers are looking at the eyelid margins to explore the association between the commensal microflora in this area and the function of the meibomian glands. What they’ve found is that lower meibum quality and function is associated with higher numbers of commensal bacteria on the eyelids. In particular, those diagnosed with ‘severe’ MGD were found to have higher numbers of microbial colonies and men, especially older men, were found to have higher counts of commensal bacteria.

They also had some interesting discoveries about MGD in women, finding that those on the verge of menopause had higher numbers of bacteria than younger women, which correlates with worsening meibomian gland function around menopause.

What is still unknown is whether the increased number of bacteria is a cause of compromised meibomian gland function, or a consequence of it or other systemic factors. The researchers believe further investigation of the interaction of age and gender with Propionibacterium (the dominant bacteria in the eyelid margin) would be useful in better understanding the role this microbial community plays.

Gene expression profiling in MGD

At the same time researchers at Brien Holden Vision Institute have undertaken gene profiling to determine if particular genes are associated with MGD. They identified none that was independently associated with the condition, concluding that this would support the ‘view of MGD as a complex disease with multiple etiological inputs.’

The research did, however, provide an insight into the biological pathways and processes which affect gland function and therefore may provide a better understanding of how MGD develops and progresses