Remember to breathe. It is after all, the secret of life.”— Gregory Maguire, A Lion Among Men

Of late, I have given a good deal of thought to the air that we breathe in and breathe out. In this “COVID Age,” we have been sensitized to pathogens that ride the air in search of a target host; our professional and personal lifestyles have been compromised by the inconveniences of face mask-wearing. One nuisance of this for our profession is lens (spectacle, phoropter, indirect) fogging from warm, spent breath.

The Air that We Breathe Out

Exhaled breath is rather interesting. Measurements/changes in the temperature and content of exhaled “air” are of value as a diagnostic tool. Exhaled breath contains a rich collection of biomarkers in three forms—gaseous breath, volatile breath, and breath condensate (Davis et al, 2018). Its temperature can indicate airway inflammation, which contributes to several lung diseases (Carpagnano et al, 2017).

The role of exhaled breath analysis has been studied in chronic obstructive pulmonary disease (COPD) risk assessment, especially in smokers, cardiovascular disease, sleep apnea (Bikov et al, 2016), lung cancer, asthma, sarcoidosis (Terrington et al, 2019), cystic fibrosis, and other pulmonary diseases (Hashoul and Haick, 2019) and in psychological stress (Tonacci et al, 2019). Analysis of exhaled breath can serve as an easy, non-invasive method to monitor inflammation and oxidative stress in the airways (Corradi and Mutti, 2005).

Nitrogen makes up 78% of the air that humans breathe out. We breathe in 21% and exhale 16% oxygen, and we breathe in 0.04% and breathe out 4% carbon dioxide, among other trace elements (Johnson, 2018). Exhaled breath contains thousands of compounds; it also contains water vapor, a byproduct of cellular respiration, at varying rates based on an individual’s health and other factors (Johnson, 2018).

It is of interest that human bacterial pathogens such as H. influenzae, P. aeruginosa, E. coli, S. aureus and methicillin-resistant S. aureus (MRSA) are detectable in exhaled breath (Zheng et al, 2018).

Effects on the Ocular Surface

I question whether these and other pathogens contained in bioaerosols are concentrated and forced upward by face mask wear onto our ocular surface, eyelids, and eyelashes, increasing the prevalence of a variety of eye infections/inflammations of the conjunctiva and lids/lash line.

It has been suggested that the microhabitats of the human eye (ocular surface, conjunctiva, lid margin, and skin) have their own bacterial population, with some bacteria shared among regions and others more limited in location (Ozcan et al, 2019). How does microbe-laden, concentrated, and mask-directed exhaled breath alter this distribution, and what is the clinical impact of this?

Has the importance and relevance of eyelid hygiene increased? Should we be more aggressive in therapeutic management of eyelid disease? What impact does face mask wear have on ocular surface disease, ocular surgery, and contact lens wear?

Our collective experience—collated—is paramount to best practices. What has your experience been? CLS

For references, please visit www.clspectrum.com/references and click on document #301.