Fluid dynamics of droplet generation from corneal tear film during non-contact tonometry in the context of pathogen transmission

Non-invasive medical diagnostics demonstrate a propensity for droplet generation and should be studied to devise risk mitigation strategies against the spread of SARS-CoV-2 virus. We investigate air-puff tonometry, which uses short-timed applanate human eye in bid detect early onset glaucoma by measuring intraocular pressure. The consists vortex trailed high-speed jet. High-speed imaging during typical tonometry measurement reveals sequence events starting with interaction between tear layer air puff leading an initial sheet ejection. It is immediately followed trailing jet applanating central corneal section, causing capillary waves form interact highly 3D transient expanding sheet. Such surrounding airfield due causes undergo bag breakup, finger formation Rayleigh Taylor instability further break up into subsequent droplets Plateau instability, eventually splashes onto nearby objects, potentially forming fomites or aerosols can lead infections. complex spatiotemporal phenomenon carefully documented rigorous experiments corroborated using comprehensive theoretical analyses.