Dry eye may be associated with an imbalance of bacteria on the eye’s surface, according to a study being undertaken at Brien Holden Vision Institute (BHVI).
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.
While key symptoms of dry eyes can include blurred vision, dryness of eyes, or eyes that are easily strained, sometimes there are no obvious signs of dry eyes when examining the patient using a slit lamp. This lack of correlation between signs and symptoms can create complications in prescribing a treatment for the patient.
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.
The BHVI researchers wrote, “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 (or ‘dysbiosis’) of this bacterial community might be contributing to destabilisation of the tear film leading to irritation and inflammation that are characteristic of dry eye.”
Further research using a population that suffers 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.