PRECIS: Designing and demonstrating an experiment that shows the risk of airborne transmission of COVID 19 between patients having visual fields analysed is low. PURPOSE: To investigate the possibility of airborne transmission of COVID-19 during Humphrey Visual field testing in a real-world scenario. METHODS: A particle counter was placed within the bowl of Humphrey Visual Field Analyser before and after turning on the machine to ascertain the effect of the air current produced by the ventilation system on aerosols. A second experiment was run where the particle counter was placed in the bowl and recorded particulates, in the air, as a 24-2 SITA standard was performed by a mock patient and then again immediately after the patient had moved away. We measured aerosol particle counts sized &#8804;0.3âµm, >0.3 &#8804;0.5âµm, >0.5 &#8804;1âµm, >1 &#8804;2.5âµm, >2.5&#8804;5âµm and >5&#8804;10âµm. RESULTS: Particulates of all sizes were shown to be significantly reduced within the bowl after turning the machine on, demonstrating that the air current produced by the Humphrey visual field analyser pushes air out of the bowl and it cannot stagnate. There was no significant difference in measurement of aerosol while there was a patient performing the test and immediately after they had moved away, suggesting that aerosols breathed out by the patient are not able to remain in suspension in the bowl due to the ventilation current. CONCLUSION: There is no significant difference between aerosol count in the bowl of a Humphrey visual field analyser before, during and after testing. This suggests the risk of airborne transmission of COVID-19 is low between subsequent patients. This is in keeping with manufacturer's guidance on Humphrey visual field testing.
Risk of Airborne COVID-19 Transmission While Performing Humphrey Visual Field Testing