Increased levels of humidity, particulate matter associated with worse signs and symptoms

Can your house make your dry eye symptoms worse?

Yes, according to researchers writing in JAMA Ophthalmology. They found that there is an association between dry eye and indoor environments — particularly increasing levels of humidity and air pollutants within that environment.

In a commentary accompanying the study, Ian J. Saldanha, MBBS, MPH, PhD, Brown University School of Public Health, Providence, Rhode Island, noted that the correlation between humidity and worse dry eye symptoms challenges conventional wisdom.

“However, as the authors rightly argue, higher humidity can amplify the effect of particulate matter by increasing its airborne time, mass, and size,” he wrote. “Thus, higher humidity is likely not a direct risk factor but may modify the association between particulate matter and worse outcomes.”

Saldanha also pointed out that, with the Covid-19 pandemic, more people are spending the majority of their time indoors at home.

“As a consequence, most patients with dry eye are now exposed to the indoor environment to a greater extent than ever before,” he wrote. “The time is ripe for identifying specific indoor environmental risk factors, which I hope can drive the development, evaluation, and refinement of more targeted and effective interventions.”

According to study authors Amy Huang, BS, Miller School of Medicine, University of Miami, Miami, Florida, and colleagues, while previous studies have focused on the effect that outdoor environmental factors can have on dry eye, research has been lacking on the association between indoor environments and dry eye.

This is a condition that affects a substantial percentage of the population. In the United States, for example, approximately 16.4 million adults (6.8%) have been diagnosed with dry eye. And, dry eye symptoms can be quite painful and result in poor or fluctuating vision.

Research has shown that dry eye is influenced by environmental factors including wind, high temperature, low humidity, altitude, and air pollution. In this study, Huang and colleagues examined the associations between indoor environmental metrics humidity, particulate matter mass concentration and count, and the symptoms and signs of dry eye.

For their study, the researchers recruited 97 individuals (mean age 58.2 years), with a wide range of dry eye metrics, from the Miami Veterans Affairs Healthcare eye clinic from Oct. 19, 2017-Aug. 30, 2018. Of those 97 veterans, 81 were men and 16 were women.

The participants had their dry eye symptoms assessed by questionnaire, including the Ocular Surface Disease Index (scores ranging from 0 to 100, with higher scores indicating greater presence of disease), while dry eye signs were assessed through ocular examination.

The participants’ symptoms of dry eye were in the moderate range, with a mean (SD) Ocular Surface Disease Index (OSDI) score of 31.2. Huang and colleagues found that humidity (r = 0.30 [95% CI, 0.07-0.49]) and airborne particulate matter greater than 5.0 μm/ft3 (r = 0.26 [95 CI, 0.03-0.47]) were most closely associated with dry eye symptom severity as measured by the OSDI.

They also determined that humidity was most closely correlated with dry eye signs, including a positive correlation with inflammation (r = 0.32 [95% CI = 0.10-0.51]), eyelid vascularity (r = 0.27 [95% CI, 0.05-0.47]) and meibomian gland dropout (r = 0.27 [95% CI, 0.05-0.47]). Humidity was also associated with worse Schirmer scores (a measure of whether tear glands produce enough tears to adequately moisten eyes).

“Overall, these results suggest that humidity is positively associated with both dry eye symptoms and signs,” wrote Huang and colleagues. “Seasonality was not found to be associated with dry eye symptoms and signs.”

When adjusted for confounders such as demographic characteristics, comorbidities, and medications, particulate matter of both 2.5 μm or less and 10 μm or less showed associations with OSDI and 3 signs of dry eye — inflammation, Schirmer score, and meibomian gland dropout.

The authors pointed out that, unlike with outdoor air pollution, individuals can adjust their indoor environments to better control humidity, temperature, and exposure to airborne particulate matter, giving them a potential therapeutic option to manage their dry eye symptoms and signs.

“These results suggest that future studies might investigate the efficacy of interventions on the indoor environment as they relate to improvements in dry eye signs and symptoms,” Huang and colleagues concluded.

  1. Indoor environments, such as an individual’s home, could exacerbate dry eye, according to study authors.

  2. Increased levels of humidity and particulate matter indoors are associated with worse dry eye signs and symptoms.

Michael Bassett, Contributing Writer, BreakingMED™

The study authors reported no disclosures.

Cat ID: 240

Topic ID: 92,240,730,192,925,240