Study shows cough droplets spread 16 feet from COVID-19 patient

August 20, 2020
David Hutton

Investigators conducted a slit lamp biomicroscope experiment, simulating a patient undergoing an eye examination and then spontaneously coughing, spraying droplets.


In a new study, a team of researchers from the University of Toronto found that cough droplets can spread more than 16 feet away from a COVID-19 patient during a slit lamp examination.

As part of the research, the investigators conducted a slit lamp biomicroscope experiment, simulating a patient undergoing an eye examination and then spontaneously coughing, spraying droplets.

Investigators noted that the study could impact the current recommended social distancing guidelines of standing or sitting 6 feet apart, which may not prevent a patent from transmitting the virus.

The study was published in JAMA Ophthalmology.

According to the report, investigators used a mannequin for the project and simulated the cough by the patient during an eye examination. An ophthalmologist wearing personal protective equipment (PPE) was positioned looking through the oculars of the microscope with a shield.

To simulate a cough, investigators placed a small latex balloon in the oral cavity of the mannequin filled with fluorescent dyed materials to be viewed under ultraviolet light.

When observed under ultraviolet light, droplets from the simulated cough were visible on the ophthalmologist's hair, chest, shoulders, arms and hands as well as on the floor, walls, and window covers of the room.

According to investigators, additional measures may be necessary beyond the current PPE and protective barriers, such as breath shields, to minimize transmission.

Investigators also noted that the use of masks for patients during a slit lamp examination can provide additional protection for the physician and should be explored in future studies.

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