COVID-19 has resulted in public health legislation in the UK mandating the wearing of facemasks in all healthcare settings by both patients and hospital staff to try and reduce viral spread [1]. This recommendation has particular relevance to a ‘close proximity’ specialty like ophthalmology [1,2,3]. Previous publications have discussed the uncertain clinical significance from the potential reduction in microbiological particles onto the surgical field when ophthalmic surgeons wear surgical masks intraoperatively, yet COVID-19 advice has now extended those principles to patients [3]. As the general population adjusts to widespread facemask use, there is an increasing awareness of Mask-Associated Dry Eye (MADE), due in part to ill-fitting designs and leakage of air [4]. We wish to report a recent case of acute post-operative MADE and discuss the implications of this public health recommendation on ocular surgery.

Painful visual loss within a few hours following routine cataract surgery is concerning, and the ophthalmologist must rule out intra-ocular conditions such as TASS or raised pressure (due to retained viscoelastic, capsule distension syndrome or aqueous misdirection). Surface problems such as traumatic corneal abrasions can present in a similar way. We believe this to be the first reported case of visual loss due to acute post-operative MADE following routine topical cataract surgery. It is likely that the poorly fitting facemask was causing the patient’s breath to be directed onto the anaesthetised post-operative ocular surface and causing a variant of exposure keratopathy. Exposure keratopathy due to inappropriate airflow has been reported in the Intensive Care Unit and in patients using ventilation machines for sleep apnoea [5, 6]. Forced airflow has also been associated with dry eye, bacterial conjunctivitis and even endophthalmitis in glaucoma patients, and this risk was our major concern in this case [6, 7]. Poorly fitting facemasks reverse the normal direction of nasal (and mouth) breathing. Rather than diverting inspiration and expiration airflow away from the eyes, such facemasks inadvertently expose the vulnerable ocular surface to mechanical desiccation and nasopharyngeal pathogens.

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