The beginning of 2021 saw the New South Wales and Victorian governments introduce mandatory use of masks in indoor settings to prevent transmission of severe acute respiratory syndrome coronavirus 2 (SARSCoV- 2). Globally, the COVID-19 pandemic has increased the use of face masks in the general population unlike ever before. Although specialised face-conforming N95 respirators are used by some, cloth masks and/or single-use surgical masks are used by most of the public and these do not fit tightly against the face. A surprising consequence has been an anecdotal increase in dry eye symptoms with such loose-fitting masks.
Face masks aim to reduce transmission of the SARS-CoV-2 virus by restricting the flow of particles from the wearer’s nose and mouth into the atmosphere and vice versa. N95 respirators are designed to block inflow of up to 95% of airborne particles that are 0.3μm or larger.1 It is unknown whether cloth and surgical masks have any such similar effectivity in blocking airborne particles. A review of several observational studies published in June 2020 in The Lancet concluded that surgical and cloth masks are 67% effective and N95 respirators 96% effective in reducing viral infections caused by pandemic-causing respiratory viruses such as COVID-19 and SARS. The advantage of N95 respirators over surgical and cloth masks is the former has a tight seal around the nose, cheeks, and chin to ensure there is no airflow bypassing the filter within the mask.
A surprising consequence has been an anecdotal increase in dry eye symptoms with such loose-fitting masks
There have been several anecdotal reports of increase in dry eye symptoms and signs during the recent pandemic. One of the early reports2 described a marked increase in ocular surface symptoms and corneal staining in patients and staff who wore masks all day. The term ‘MADE’ for ‘mask associated dry eye’ was coined by an Ohio ophthalmologist3 who noticed an increase in dry eye amongst his mask-wearing patients. A pilot study of mask wearers in Bulgaria4 likewise found that regular users of surgical masks (along with occasional use of N95-like respirators) for ≥6 hours/day experience significantly worse symptoms of eye discomfort, redness, tearing, burning, dry eye, itching and foreign body sensation, than those who wore masks incidentally. Accompanying these symptoms were ocular surface changes such as corneal staining, reduced tear breakup time and Schirmer scores. The presence and severity of symptoms was significantly associated with length of time that masks were worn during the day.
Similarly to what has previously been reported in sleep apnoea patients using CPAP machines,5 it is likely that MADE symptoms occur because exhaled air flows upwards from beneath loose-fitting masks towards the ocular surface. This air has a temperature of 36–37℃ as well as increased carbon dioxide and decreased oxygen concentration – all of which adversely affect the tear film, causing instability, greater evaporation, hyperosmolarity and reduced tear pH. The use of a face shield further increases the temperature of exhaled air that the ocular surface is exposed to, due to reduced availability of cool ambient air for the exhaled air to mix with, near the ocular surface.
It is conceivable that MADE may lead to greater face or eye touching. Whether this increases the risk of virus transmission through the ocular surface is unknown. In the context of this potential increase in face or eye touching, good hand hygiene becomes crucial to reduce transmission of virus from fingers to the face and ocular surface.
Optometrists as primary care practitioners are well placed to monitor for and manage any increased occurrence of MADE. Those required to wear masks for long hours regularly, and those with pre-existing ocular surface disease, are potentially at greater risk of developing MADE. Patients with risk factors for ocular surface disease should thus be warned to look out for eye symptoms associated with mask wearing. Such patients include the elderly, contact lens wearers, those suffering from systemic conditions such as Sjogren’s syndrome, connective tissue disease and those on certain medications such as antihistamines, anti-depressants and topical anti-glaucoma medications.6
- Ask mask-using patients how their eyes are feeling and whether they are having any eye symptoms. Be alert to this, particularly in patients with pre-existing ocular surface disease.
- Encourage regular use of non-preserved lubricants.
- Discourage rubbing and repeated touching of the eyes to relieve irritation.
- Use masks with a metal strip at the nose, which can be pushed to fit the contour of the nose, limiting air flow leaks upwards towards the eye.
- Limit exposure to other known risk factors for dry eye disease such as electronic screen use and air conditioning.
Caution should be exercised with taping the upper edge of the mask to the cheek as this may result in ectropion, especially in the elderly. Additionally, restriction in movement of the inferior lid can compromise blink action and tear spread, resulting in exposure keratopathy.
The infographic designed by researchers at the University of Waterloo and included on page 14, is useful to help explain to patients why their dry eye symptoms are increased with mask use.
Sukanya Jaiswal graduated with a Bachelor’s degree in Optometry and Vision Science in 2013, Masters in Optometry in 2020 and is currently pursuing a PhD at the School of Optometry and Vision Science at UNSW Sydney.
Blanka Golebiowski is an optometrist and Associate Professor in the School of Optometry and Vision Science at UNSW. Her research aims to understand the mechanisms of dry eye and eye pain, in order to inform the development of effective new treatments.
Isabelle Jalbert is an optometrist and Associate Professor in the School of Optometry and Vision Science at UNSW Sydney. Her research focuses on evidence-based eye care, eye care quality and health education.
- Peeples, L. What the data say about wearing face masks. Nature 2020; 586: 186-189
- Moshirfar, M, West, WB, Marx, DPJO et al. Face maskassociated ocular irritation and dryness. Ophthalmol Ther 2020; 9: 397-400
- White DE, M. Healio Ophthalmology. MADE: A new coronavirus-associated eye disease: 2020
- Marinova, E, Dabov, D, Zdravkov, YJB et al. Ophthalmic complaints in face-mask wearing: prevalence, treatment, and prevention with a potential protective effect against SARSCoV- 2. Biotechnology & Biotechnological Equipment 2020; 34: 1323-1335
- Hayirci, E, Yagci, A, Palamar, M et al. The effect of continuous positive airway pressure treatment for obstructive sleep apnea syndrome on the ocular surface. Cornea 2012; 31: 604-608
- Craig, JP, Nelson, JD, Azar, DT et al. TFOS DEWS II report executive summary. Ocul Surf 2017; 15: 802-812