Efficacy of Patient-Sided Breath Shields for Slit-Lamp Examination
Muhammad Azaan Khan,1 Gizem Hasimoglu,2 Hamza Ashraf,2, Geoff Wilcsek,1,3,4
1. University of New South Wales, Australia
2. Monash University, Australia
3. Prince of Wales Hospital, Australia
4. Macquarie University Hospital
Purpose
To evaluate the efficacy of patient-sided breath shields in preventing oronasal droplet transmission during slit-lamp examination.
Design
Experimental study testing the efficacy of patient-sided breath shields on a slit-lamp.
Methods
Two commercially available patient-sided breath shields and a 3D-printed shield designed by the authors were attached to a slit-lamp chin rest for testing. Each shield was exposed to three standardised sprays of coloured dye from a spray gun, with its nozzle adjusted to simulate the angular dispersion of a human sneeze. Any overspray not blocked by the shields was recorded and compared to spray with no shield (control). Image-processing software was used to ascertain the surface area of overspray with comparison to the control.
Results
With typical use, both commercially available patient-sided shields and the 3D-printed shield blocked 100% of forward travelling measurable droplets from a simulated sneeze spray. Even when set to the furthest distance setting to simulate the worst-case scenario, shield 1 and the 3D-printed shield blocked 99.96 and 99.65% of overspray, respectively. However, slow-motion footage did reveal that a considerable amount of spray rebounded off the shields and extended peripherally past its borders.
Conclusions
With typical use, all tested shields prevented 100% of oronasal transmission. To encourage accessibility, we offer a free 3D model and instructions for creating the tested patient-sided breath shield. Patient-sided shields should be combined with other infection control measures to minimise transmission.