Keeping an Eye on COVID-19

Working in high-volume clinics with close and prolonged proximity to patients puts ophthalmologists at risk of contracting COVID-19. The risk significantly reduces, however, if both patients and physicians wear surgical masks. Moreover, the COVID-related mortality rate for US physicians has fallen since the start of the pandemic, is currently lower among physicians than in the non-physician population, and is lower among ophthalmologists compared to some other medical specialists, according to Azin Abazari MD.

Speaking during a symposium devoted to the topic, Dr Abazari helped distil the latest information on SARS-CoV-2’s impact on ocular health and the practice of ophthalmology. She noted incidents such as Chinese ophthalmologist Dr Li Wenliang’s death in February 2020—just a few months after warning of an outbreak—raised early concern that ophthalmologists might be more susceptible to contracting the viral infection.

“Over the past two and a half years, however, our understanding of the SARS-CoV-2 virus, its transmission, and its implication for ophthalmology have evolved,” Dr Abazari said.

Reviewing current knowledge, she said COVID-19 transmission is thought to mostly occur through exposure to droplet particles emitted from the respiratory tract of infected persons. The droplets, however, travel only about one to two metres and do not remain suspended in the environment for very long. Thus, transmission via droplets requires being in the same room, at the same time, with the infected person.

Aerosols, which are smaller particles than droplets, can remain suspended in the environment and travel farther than droplets. They can also transmit infection even if the infected individual is not in the same place as the susceptible person or in a relatively enclosed space with poor ventilation.

“According to the World Health Organisation, aerosol transmission of COVID-19 is not proven,” Dr Abazari said, adding that contact with contaminated surfaces is considered a minor mode of COVID transmission.

PCR can detect viral RNA in tear or conjunctival samples of a small minority of COVID-positive patients. Dr Abazari stressed the importance of knowing there is no proven risk of transmission because of contact with tears or conjunctiva of a COVID-positive individual. RNA particles can be detected in tear or conjunctiva of patients simply because of exposure to aerosolised particles or viremia in the setting of systemic infection.

PREVENTING INFECTION

Understanding COVID transmission occurs mainly through droplets provides a basis for recommending strategies to prevent disease contraction, including the recommendation of ophthalmologists and patients both wearing surgical masks.

“Some studies show that surgical masks worn by both parties are as protective as the physician alone wearing an N-95 mask,” Dr Abazari said.

Other recommendations include administering screening questionnaires to patients prior to their visit and using breath shields on the slit lamp, although these need frequent sanitising. Careful hand hygiene and disinfecting/sanitising other equipment will reduce contact transmission but are less important since contact with contaminated surfaces is a minor means of transmission.

This presentation was made at AAO 2022 in Chicago, US.

Azin Abazari MD is an Associate Professor of Ophthalmology, SUNY Stony Brook, Stony Brook, New York, US. azin.abazari@stonybrookmedicine.edu