Dry eyes: caused by an imbalance of bacteria on the eye's surface? FB Twitter LinkedIn

Dry eyes: caused by an imbalance of bacteria on the eye's surface?

Rebecca Weng, Dr Kah Ooi Tan, Daniel Tilia

Sydney, Australia, 13 November 2017: Most people have experienced dry eyes at some point in their life and the discomfort experienced is a major reason for visiting an optometrist. Key symptoms of dry eyes can include blurred vision, dryness of eyes, or eyes that are easily strained. A patient visiting the optometrist might expect that the diagnosis would be quick, and a simple solution would be offered.

For an optometrist, the complexity arises when they are not able to spot any obvious signs of dry eyes when examining the patient using a slit lamp. This can create complications in prescribing a treatment for the patient due to a lack of correlation between signs and symptoms.

The surface of the eye is complex and is covered by a thin tear film that is made up of three layers; the lipid (oil) layer, the aqueous (water) layer and the mucin layer. This film keeps the eyes lubricated and protects the eyes against infection.

We are just beginning to understand that a healthy ocular surface has a community of bacteria living on the surface. These bacteria are usually harmless due to the protective barrier afforded by a stable tear film. In relation to dry eye there is increasing evidence that an imbalance of this bacterial community might be contributing to destabilisation of the tear film leading to irritation and inflammation that are characteristic of dry eye.

Our researchers are investigating if an imbalance or ‘dysbiosis’ of bacteria on the ocular surface is contributing to an unstable tear film and thus contributing to dry eyes. As part of the research, optometrists collected bacterial samples from each participant, and the samples were analysed to record the makeup of the bacterial community on the ocular surface. Following the sample collection, the participant filled in two surveys (McMonnies questionnaires and the Ocular Surface Disease Index (OSDI)) to assess the severity of their dry eyes symptoms. The study was conducted on a healthy population.

The outcome of the study suggested that within this healthy population, although there were no strong correlations between the specific bacterial species and dry eye, there were suggestions that a higher bacterial burden is correlated with increased signs of dry eye.

Further research using a population who suffer from dry eye is required to unlock the answer to: “does the imbalance of ocular surface bacteria cause the tear film to be unstable?", and, if so, "is it a major contributor to dry eye disease?”

The Brien Holden Vision Institute is currently investigating a novel treatment for dry eye.