Researchers estimate people spend more than 90% of time indoors—and they now know that the environment in which they live plays an important role in ocular health. In a recent study, researchers found that indoor humidity was associated with elevated concentrations of airborne microbes, especially in older homes, and microbial exposure showed a strong association with meibomian gland dysfunction, even after adjusting for known confounders such as age.

The investigators recruited 157 individuals with normal external ocular anatomy who underwent a clinical evaluation that included a dry eye assessment. Additionally, the team sampled and assessed the patients’ indoor air. Out of the 157 original enrollees, 93 completed a six-month follow-up home and clinical visits.

The study found more microbial colonies in older homes. A 1% increase in humidity was associated with a 3% increase in nutrient microbial colonies.

After adjusting for age and gender, the researchers found the number of microbial colonies was significantly associated with two dry eye measures: corneal epithelial disruption and meibomian gland dropout. The number of microbial colonies found in the air and patient age showed significant associations with lower lid meibomian gland dropout, while other dry eye measures were not strongly linked to the presence of microbial colonies.

Microbial colony exposure may be a useful target for meibomian gland dropout intervention, the researchers noted.

Rock S, Galor A, Kumar N. Indoor airborne microbial concentration and dry eye. Am J Ophthalmol. October 14, 2020. [Epub ahead of print].