Even short-term exposure to increased ground-level ozone concentrations can intensify ocular discomfort and decrease tear secretion for patients with dry eye, a new study published in Cornea says. Ozone, the report shows, is among the most harmful air pollutants and can be associated with cardiovascular and respiratory disease as well as dry eye disease (DED). Ozone can induce damage to cellular proteins and lipids through the production of reactive oxygen species, according to the investigators.

The Korean research team looked at 33 patients with DED. All patients were treated with 0.05% cyclosporine or 3% diquafosol and visited the hospital twice at two-month intervals. Patients who showed a short tear film break-up time and positive ocular surface staining were assigned to the diquafosol and cyclosporine groups, respectively. Researchers then measured their ocular surface disease index (OSDI) score, tear secretion, tear film break-up time and examined them using corneal fluorescein staining. The researchers also documented the mean ground-level ozone concentration one week before the scheduled ocular examinations.

Positive changes in the ozone concentrations were significantly associated with a 3.43 increase in OSDI scores and a 1.43mm decrease in tear secretion. The ozone effects were more prominent among women and those treated with cyclosporine, the study found.

“Ozone-induced inflammation of the ocular surface and lacrimal glands may be correlated with these results,” the researchers concluded. 

Kim Y, Paik H, Kim M, et al. Short-term effects of ground-level ozone in patients with dry eye disease: a prospective clinical study. Cornea. July 3, 2019. [Epub ahead of print].