key: cord-0817360-rwnubdob
authors: Goudie, Colin R.; Khan, Ashraf; Cackett, Peter; Bennett, Harry G.B.
title: RE: Khan MA et al: Perceptions of Occupational Risk and Changes in Clinical Practice of U.S. Vitreoretinal Surgery Fellows during the COVID-19 Pandemic (Ophthalmol Retina. 2020;4:1181–1187)
date: 2021-04-01
journal: Ophthalmol Retina
DOI: 10.1016/j.oret.2021.01.006
sha: 2bdb8567a8666ba9a6d25a7c3adbf5ec32c64b1a
doc_id: 817360
cord_uid: rwnubdob

nan

TO THE EDITOR: The rapidly evolving situation when severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged necessitated an update in the healthcare protection guidance. The virus is transmitted through contact with respiratory droplets (>5e10 mm) and to a lesser extent through airborne transmission of droplet nuclei (<5 mm) in aerosols. For ophthalmologists, there have been particular concerns regarding potential for aerosol transmission of SARS-CoV-2 during operative procedures. 1 Initially, advice from the Royal College of Ophthalmologists in the United Kingdom (UK) recommended that operating room staff use filtering facepiece respirator class P13 masks with eye protection when performing phacoemulsification or vitrectomy, while acknowledging uncertainty regarding evidence for this guidance. 2 Subsequently, it was thought by both UK-and United States (US)-based organizations that standard personal protective equipment (PPE) would be sufficient. 3, 4 We believe that the updated guidance stating that these procedures are not aerosol generating is correct. SARS-CoV-2 has been found in tears of infected patients, but its intraocular presence has not been demonstrated. Furthermore, the use of povidoneiodine provides a 99.99% reduction of viral load of severe acute respiratory syndrome coronavirus and Middle East Respiratory Syndrome coronavirus, and this is likely to be the case with SARS-CoV-2. 5 Therefore, any SARS-CoV-2 present in ophthalmic surgery would be eradicated by the use of povidone-iodine. During phacoemulsification, the aqueous is replaced with viscoelastic and then with balanced salt saline (BSS); therefore, even if the procedure generated aerosol, it would be only BSS. Vitrectomy is performed through valved trocar cannulae, and so any potential aerosol would also be BSS, which would be contained within the eye even during fluideair exchange.

Depending on light conditions and particle scatter, the human eye may distinguish particles as small as 10 mm. Reliably measuring smaller aerosol production requires specialized imaging equipment in a controlled laboratory setting. In our unit, we were keen to investigate the potential for visible fluid leak or generation of spray, which could indicate aerosol transmission during phacoemulsification and vitrectomy. We performed both 25-gauge vitrectomy and phacoemulsification (2.2-mm wound) (both procedures using D.O.R.C. EVA) on a model eye (Phillips Studio) irrigated with fluorescein-stained BSS and examined for signs of aerosol production. During vitrectomy, static drops of BSS were seen at the port sites under high infusion pressure. Examination was performed during and after the pro-cedure using both white and cobalt blue light observed with the naked eye, and still images and video recorded using a Nikon DS7500 camera. We were unable to identify visible spray at any stage using a cutter and lightpipe or during passive aspiration. No drops of BSS or spray were seen at wound sites during phacoemulsification. Postoperative examination of the surgeon showed a few drops on the gloves, with no signs of spray on the gown, mask, or visor, using both white and blue light. In the absence of leakage from wounds or valved trocar cannulae, there is no route by which any generated aerosol could leave the confines of the eye.

Following our study, we believe we have provided further evidence to support the UK and US guidance outlining that the risk of aerosol transmission is minimal and standard PPE is sufficient for these procedures.

Perceptions of occupational risk and changes in clinical practice of U.S. Vitreoretinal Surgery Fellows during the COVID-19 Pandemic

Cataract surgery: protecting patients and professionals during COVID-19

Assessing the evidence base for medical procedures which create a higher risk of respiratory infection transmission from patient to healthcare worker

Special considerations for ophthalmic surgery during the COVID-19 pandemic

Topical preparations to reduce SARS-CoV-2 aerosolization in head and neck mucosal surgery