Production and characterization of drug-loaded toroidal vortices from a novel ocular drug delivery device.

For the last several decades, the predominant method for delivering medicine to the surface of the eye has been the standard multiuse eye dropper. While being the most popular, this method has significant limitations. Recently, an effort has been made to explore the use of a directed toroidal vortex or "smoke ring" aerosol delivery system that may help overcome these limitations and enable delivery of precise amounts of formulation and drug to the ocular surface. Promising preliminary in vitro studies indicated dosing control, but the physical characteristics of the toriodal aerosol device performance and impaction forces related to patient comfort have yet to be established. Here, we experimentally investigate the mechanics and dynamics of these ocular aerosol vortices, including translational and rotational velocities, spatial droplet size distributions, and relative impaction forces in order to optimize the device performance and evaluate potential for clinical use. Maximal droplet velocity at various actuation forces was determined, and they were found to be all less than 6 m/s even at the highest actuation forces. Moreover, plume impaction forces were determined across a range of conditions and were all less than about 4.5 μN. Collectively, these studies showed that the physical and mechanical properties of the emitted drug-loaded vortices would be suitable for ocular administration.