The influence of slit lamp shield size and design in reducing aerosol transmission

Author: Mussa Butt (United Kingdom)

Co-authors: Mahmut Dogramaci

Purpose

Previous studies have highlighted the effectiveness of slit lamp shields in reducing aerosol spread. Our study investigated the optimal size and design for such shields.

Setting/Venue

Princess Alexandra Hospital

Methods

Two sets of shields were made; each set included five cardboards of the following dimensions 1:(44x52cm), 2:(44x44cm), 3:(22x52cm), 4:(22x33.5cm) and 5:(44x22.5cm). Cardboards in set 1 were kept flat while in set 2 were curved using plastic frames. Aerosol was generated at patient’s position using water spray bottle while aerosol levels were measured at the face position of the examiner and on the slit lamp desk using two GP2Y1014AU0F sensors. The measurements were recorded in particles/0.01f3 and analysed using a Mann Whitney U Test.

Results

Mean background indoor aerosol was 559. Following aerosol generation, the level increased to a mean of 571 in the absence of any kind of shield but to a mean of 567 when shields were in place (p<0.05). Flat shield 1 provided the best protection against inhaled aerosol. Flat shield 2, despite of its shorter height compared to shield 1, provides best protection against precipitated aerosol on slit lamp desk. Curving shield 5 has significantly improved its protective properties against both inhaled and precipitated aerosol, while keeping its shortest height that allows better access during slit lamp examinations.

Conlusions

Shields reduced aerosol spread with curved shields being more effective. GP2Y1014AU0F particle sensors are effective tools for quantifying aerosol spread. Slit lamp parts could change the aerodynamic of aerosol transmission therefore larger shields may not provide better protection against precipitated aerosols.

Financial Disclosure

The detectors used in this study were sponsored by VR Surgical Consulting Ltd.