A recent study published in Contact Lens & Anterior Eye led by a team of researchers from Spain performed a literature review to evaluate the link between physical activity and symptoms of dry eye disease (DED).
Talk about the study.
In this meta-analysis study, investigators reviewed 16 papers from the PubMed and Web of Science databases to determine the association between exercise and DED symptoms.
These papers evaluated dry eye-associated signs, such as changes in tear volume, osmolarity, and/or biochemical composition, as well as dry eye subjective symptoms in patients primarily between the ages of 20 and 70 (with one paper assessing pediatrics and an inclusion of a small number of patients over the age of 70 in the remaining papers).
Go on…
Of the 16 papers, eight measured the changes in dry eye signs after a single, acute session of aerobic exercise, while the other eight studies measured the changes in dry eye symptoms in relation to the long-term practice of physical activity.
Findings?
In general across the studies, it was shown that after performing a short period of high to maximal-intensity aerobic exercise:
- Tear volume increased
- Tear osmolarity increased
- Tear breakup time (TBUT) did not change or was prolonged
However, the length of these responses and if they were maintained after repeated bouts of exercise is still unknown.
Tell me more.
Interestingly, a potential link between osmolarity and oxygen bioavailability was identified.
The study authors noted that the increase in tear film osmolarity in response to high or maximal-intensity exercise was lower after supplemental oxygen administration and in individuals with high maximal oxygen uptake.
Additionally, investigators hypothesized that during physical activity, the simultaneous activity of both autonomic divisions of the nervous system on the lacrimal gland could influence the increased tear volume and/or its differential in composition after exercise.
Anything else?
Researchers observed that habitual physical activity led to a long-term adaptation of the autonomic nervous system, increasing the so-called “parasympathetic tone.”
They hypothesized that higher basal tonic activity of the parasympathetic nervous system could improve both lacrimal gland secretion and the physiological function of the meibomian glands.
Significance?
This literature review shows strong evidence to suggest that physical activity could act as a modulatory stimulus to maintain the proper functionality of the tear film while possibly alleviating the signs and symptoms of DED.