"Fluid Dynamics of Droplet Generation from Corneal Tear Film during Non-contact Tonometry in the Context of Pathogen Transmission" is published online in Physics of Fluids (Vol.33, Issue 9). The article can be accessed via the link below:
https://doi.org/10.1063/5.0061956 DOI: 10.1063/5.0061956
Team: Durbar Roy, Sophia M, Abdur Rasheed, Prasenjit Kabi, Abhijit Sinha Roy, Rohit Shetty, and Saptarshi Basu
Description: Noninvasive ocular diagnostics demonstrate a propensity for droplet generation and present a potential pathway of distribution for pathogens such as the severe acute respiratory syndrome coronavirus 2. High-speed images of the eye subjected to air puff tonometry (glaucoma detection) reveal three-dimensional, spatiotemporal interaction between the puff and tear film. The interaction finally leads to the rupture and breakup of the tear film culminating into sub-millimeter sized droplet projectiles traveling at speeds of 0.2 m/s. The calculated droplet spread radius (∼0.5 m) confirms the likelihood of the procedure to generate droplets that may disperse in air as well as splash on instruments, raising the potential of infection. We provide a detailed physical exposition of the entire procedure using high fidelity experiments and theoretical modeling. We conclude that air puff induced corneal deformation and subsequent capillary waves lead to flow instabilities (Rayleigh–Taylor, Rayleigh–Plateau) that lead to tear film ejection, expansion, stretching, and subsequent droplet formation.