Although many questions about COVID-19 remain, there is evidence to suggest the virus spreads through direct contact and aerosolized droplets from an infected person—bringing tonometry best practices into question. Many are moving to non-contact options to avoid direct contact with patients—but even that could pose a risk, a new study suggests. Researchers are now recommending clinicians avoid non-contact tonometry (NCT) in patients with high tear volume, whether natural or due to eye drops, as the diagnostic procedure could spread droplets to the device and the operator.
This experimental study evaluated eight healthy participants. A team performed NCT on one eye each of the eight participants in three scenarios: normal setting, one drop of lubricant and two drops of lubricant. They used high-speed shadowgraphy, frontal lighting and fluorescein analysis to detect any possible droplets or aerosols.
In a natural setting, the investigators found no droplet or aerosol production. However, they reported minimal splatter and droplet ejection with one drop of lubricant prior to NCT. With two drops of lubricant, they added that there was a significant amount of fluid ejection that broke up into multiple droplets. They noted that some of these droplets traversed back to the tonometer. They measured droplets ranging from 100μm to 500μm in diameter.
The researchers stress the need for further studies that assess the best methods of protecting the operator and disinfecting the device, suggesting the use of a protective shield on the operator’s face and ensuring proper ventilation with airflow to minimize contact with any potential droplets.
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Shetty R, Balakrishnan N, Shroff S, et al. Quantitative high-speed assessment of droplet and aerosol from an eye after impact with an air-puff amid COVID-19 scenario. J Glaucoma. September 17, 2020. [Epub ahead of print].