key: cord-290414-8i8g0xdc
authors: Chuan, Ong Sze; Bin Razali, Muhammad Azri; Shaffiee, Lyana; Xing, Yap Jun; Yin Fei, Terrence Tay; Chee, Loon Seng; Koh, Victor
title: Do slit lamp shields and face masks protect ophthalmologists amidst COVID-19?
date: 2020-06-21
journal: Ophthalmology
DOI: 10.1016/j.ophtha.2020.06.031
sha: 
doc_id: 290414
cord_uid: 8i8g0xdc

Unlike face masks which provided some protection against both aerosols and droplets, slit lamp shields conferred protection only against direct large droplet transmission, with a limited role in reducing aerosol transmission risk.

The SARS-CoV-2 is primarily transmitted via respiratory droplets, contact with 1 contaminated surfaces, or free-floating aerosols. 1, 2 

Ophthalmology recommends the use of surgical masks, and commercially-available slit lamp 3 shields (Breath Shields, Carl Zeiss AG, Oberkochen, Germany). 3 However, there is lack of 4 evidence regarding the true efficacy of slit lamp shields. We attempted to replicate the 5 spread of infected aerosols and large droplets in the clinical setting of a slit lamp 6 examination, to evaluate the efficacy of protective equipment in reducing the risk of viral 7

This study adhered to the Declaration of Helsinki, and IRB approval was not required. 9

Aerosols were defined as smaller light particles which remain suspended in the air due to 10 slow settling velocity, while large droplets were heavier particles which fall rapidly following a 11 downward trajectory. 4 The experimental setup ( Figure S1 , available online at 12 www.aaojournal.org) consisted of a slit lamp (B900 Slit Lamp, Haag-Streit Holding AG, 13 Switzerland), a mannequin face which represented the ophthalmologist, and a spray bottle at 14 the chin rest which represented respiratory particle production from the patient. A particle 15 produced by the spray bottle had peak velocity of 4.0 meters/second and maximum 16 horizontal distance of 2.35 meters, which was comparable to particle behavior by coughing 17 or sneezing. A high-speed camera capturing 1000 frames/second (Chronis 1.4, Kron 18

Technologies Inc., Canada) was used for video recordings (Figure 1 ). This process was 19 

Coronavirus in China

Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1

Important coronavirus updates for ophthalmologists

Accessed

Transmission routes of respiratory viruses among humans

Face shields for infection control: A review

Potential utilities of mask-wearing and instant hand hygiene for fighting SARS-CoV-2

Effectiveness of Surgical and Cotton Masks in Blocking SARS-CoV-2: A Controlled Comparison in 4 Patients