# Quantification of Droplet Aerosol Generation During Phacoemulsification and Pars Plana Vitrectomy

## TL;DR

This study measures droplet aerosol generation during cataract and vitrectomy surgeries to assess infection risks, finding that smaller incisions and HPMC coating reduce aerosol production.

## Contribution

The first study to use whole cadaveric human eyes with a high-sensitivity particle spectrometer to quantify aerosol generation during phacoemulsification and vitrectomy.

## Key findings

- 2.2 mm corneal incisions produced fewer aerosols than 2.75 mm incisions during phacoemulsification.
- HPMC coating significantly reduced aerosol counts during surgery.
- Droplet aerosols were generated during vitrectomy only when air infusion occurred through a leaking trocar valve.

## Abstract

Introduction

Intraocular procedures such as phacoemulsification and pars plana vitrectomy (PPV) may generate fine droplet aerosols that are relevant to infection control, particularly in the context of SARS-CoV-2. Data on aerosol production during cataract and vitrectomy surgery, especially in human tissue and with different wound constructions, remain limited. This study used a high-sensitivity optical particle spectrometer to quantify droplet aerosols (0.12-8.00 μm in diameter) generated during phacoemulsification in cadaveric human eyes with 2.2 mm and 2.75 mm corneal incisions, to assess whether hydroxypropyl methylcellulose (HPMC) reduces aerosol production, and to measure aerosol generation during individual steps of PPV.

Methods

Tests were performed on one model eye and two human cadaveric eyes. A printed optical particle spectrometer (POPS) was used to measure droplet aerosol generation during phacoemulsification through 2.2 mm and 2.75 mm main corneal incisions, with and without HPMC coating, and during predefined stages of 23-gauge PPV. Particle number concentration (PNC, particles cm⁻³) was recorded each second and summarised as mean PNC for each condition.

Results

In this small series, mean PNC during phacoemulsification without HPMC appeared to be higher with 2.75 mm incisions than with 2.2 mm incisions, and counts of particles >1 μm in diameter were also greater. Application of HPMC was associated with reduced aerosol counts. The maximum measured mean PNC without HPMC for 2.2 mm corneal incisions was 88 cm⁻³, which fell to 66 cm⁻³ with HPMC (p<0.05). For 2.75 mm incisions, the maximum measured mean PNC without HPMC was 493 cm⁻³, falling to 61 cm⁻³ with HPMC (p<0.05). No increase in droplet aerosol was detected during vitrectomy apart from during air infusion through a leaking trocar valve.

Conclusion

To our knowledge, this is the first study to use whole cadaveric human eyes in combination with a high-sensitivity optical particle spectrometer to quantify airborne particle number and size during phacoemulsification and PPV. In this model, droplet aerosol production during cataract surgery appeared lower with 2.2 mm incisions and with HPMC coating of the cornea. Droplet aerosols may be generated during vitrectomy when air infusion is delivered through a leaking trocar valve, highlighting the importance of port integrity.