Efficacy of Slit Lamp Breath Shields

Abstract

To evaluate the efficacy of slit lamp breath shields to prevent droplet spray from a simulated sneeze.DESIGN: Experimental study to test the effectiveness of personal protective equipment.METHODS: The nozzle of a spray gun was adjusted to angularly disperse a mist of colored dye that approximated a patient sneezing on a dimensionally accurate cardboard slit lamp model. The designs of 6 commercially available breath shields and 1 breath shield repurposed from a plastic container lid were tested. Each breath shield was sprayed in a standardized fashion 3 times, and the amount of overspray was compared to spray with no shield and quantified. The surface area that was sprayed was calculated using a commercially available software with color range function. The average percentage of overspray of each breath shield was computed in comparison to the control.RESULTS: The breath shields ranged in surface area from 116 to 924 cm 2 , and the amount of overspray varied from 54% to virtually none. Larger breath shields offered better protection than smaller ones. Breath shields attached to the objective lens arm were better barriers than those of comparable size hung by the oculars. A repurposed plastic lid breath shield, 513 cm 2 , was slightly curved toward the examiner's face and allowed only 2% overspray. The largest breath shield (924 cm 2 ) hung near the oculars and prevented essentially all overspray.CONCLUSIONS: The performance of different designs of breath shields was variable. Even high-functioning shields should be used in conjunction with personal protective equipment including masks, goggles, and gloves and handwashing. Ideally patients should also wear a face mask during all slit lamp examinations.

Assessment of Respiratory Droplet Transmission During the Ophthalmic Slit-Lamp Exam: A Particle Tracking Analysis

“…Without any protection, we also note fewer droplets reaching the patient than the examiner. As the slit lamp shield hanging from the oculars is 3 cm closer to the examiner than the patient, these data are also consistent with previous reports that closer shield distance prevents greater spread of respiratory droplets 1 . We also identify the slit lamp joystick and examination table as a high-risk area for contamination given its location under the shield, suggesting that gloves may prevent physician contact with droplets.…”

“…Furthermore, the pandemic has resulted in fervent discussion regarding best practices to limit the spread of infectious diseases in the clinical setting. This disease, like many other upper respiratory infections, is highly transmissible via respiratory droplets, with recent reports suggesting airborne transmission of the can also occur 1 , 2 , 3 .…”

“…As clinical activities resume, there is a need for robust data to inform use and efficacy of PPE in the clinic. Recent work compared several commercially available slit lamp shields for degree of respiratory droplet spread protection, providing necessary evidence for best clinical practice 1 . However, several open questions remain for the development of best-practice, evidence-based guidelines for PPE during the ophthalmic exam.…”

Assessing the Physiological Relevance of Cough Simulators for Respiratory Droplet Dispersion

“…In order to develop and inform best practices for personal protective equipment, various simulations of respiratory and aerosolized droplet dispersion have been conducted. However, it is unclear which of these methods of simulation, if any, approximate physiologic breathing or coughing [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. This is an important issue as data from these experiments are often used to inform guidelines for personal protective equipment (PPE) in the COVID-19 era.…”

Utility of patient face masks to limit droplet spread from simulated coughs at the slit lamp

“…However, breath shields may not fully eliminate the spread of droplets. 2 The use of masks by patients has been shown to mitigate the emission of various viruses into the environment and is recommended by the Centers for Disease Control and Prevention. 3 Herein, we aimed to investigate how various scenarios of masks worn by patients can reduce the spread of respiratory droplets onto the examiner during a slit-lamp examination using a simulated patient cough.…”