LAUSR

that aerosols may be produced during phacoemulsification but not during PPV. Although phacoemulsification may generate aerosols, currently there is no evidence showing the presence of SARS-CoV-2 in aqueous humour. Even if the virus was present, the aqueous is first replaced with viscoelastic and then with balanced salt solution (BSS) at the start of phacoemulsification. Consequently, by the time sculpting commences, it is BSS that is aerosolized rather than aqueous. We therefore support the rationale behind national (Royal College of Ophthalmologists, 2020) and international guidance (American Academy of Ophthalmology, 2020) on intraocular surgery during the COVID-19 pandemic, which suggests that the risk of aerosolized virus during phacoemulsification is likely to be very low. We did not measure a significant rise in particle concentration during PPV. This could be explained by virtue of this procedure being performed through valved port cannulas, within a closed system, such that any aerosol generated is contained within the eye. A limitation of our approach is the use of model eyes, which do not possess the same biomechanical properties as human eyes. Additionally, we used an optical particle counter which does not distinguish between infectious and noninfectious particles. Nevertheless, our study yields the first quantitative data on aerosol generation during intraocular surgery. Further research to confirm our model eye findings in a human eye is warranted.