Aerosol formation during non-contact “air-puff” tonometry and its significance for prevention of COVID-19

Authors: Li Chunchun,  Tang Yuan,  Chen Zhangyan,  Wang Aisun,  Huang Xiaoqiong,  Chen Yanyan,  Qu Jia

DOI: 10.3760/cma.j.issn.115989-20200226-00112
Published 2020-03-10
Cite as Chin J Exp Ophthalmol, 2020,38(03): 212-216.

Abstract

Objective

To evaluate the aerosol and concentration (PM2.5, PM10 and aerosol particle number) formation in non-contact “air-puff” tonometry and provide suggestions for medical workers to take appropriate daily protection during the prevalence of 2019-nCoV.

Methods

A cross-sectional study was carried out in this study.Thirty healthy subjects were enrolled on February 22, 2020 in Eye Hospital of Wenzhou Medical University.The intraocular pressure (IOP) was measured by non-contact “air-puff” tonometer in the ophthalmic consulting room and the hall with or without masks.Particulate matter (PM)2.5, PM10 and aerosol particles were recorded by air quality detector.The cumulative effects of IOP measurement, PM2.5, PM10 and aerosol particle number were analyzed, and the aerosol density of subjects with and without masks was compared.

Results

The PM2.5, PM10 and aerosol particles produced by the non-contact “air-puff” tonometry and increased with the increase of spray times.The IOP curves of 60 eyes of 30 subjects were measured respectively in two environments of medical consulting room and medical institution hall.It was found that PM2.5, PM10 and particle number fluctuated and increased with the increase of IOP measurement person times, showing cumulative effect, and the accumulation speed of aerosol density in hall was faster than that in consulting room.The density of PM2.5 and PM10 produced without gauze mask were (53.417±2.306) and (85.350± 3.488) μg/m3, which were higher than those of (50.567±0.862) and (80.617±1.463) μg/m3 with gauze mask.The differences were statistically significant (P=0.028, 0.019), and significant difference was found in aerosol density between with and without gauze mask, although more aerosol was produced without gauze mask in comparison to gauze mask (P=0.123).

Conclusions

Aerosol can be produced by non-contact “air-puff” tonometer spraying, and it fluctuates with the increase of spraying times, showing a cumulative effect.The aerosol and particulate matter accumulation is higher in the hall with insufficient air circulation, and more aerosol and PM can be produced without gauze mask.

Key words:

Tonometer, non-contact “air-puff”; Aerosol; Particulate matter; Infection; Transmission; Corona virus disease-19

Contributor Information

Li Chunchun
Ophthalmology and Optometry, Eye Hospital of Wenzhou Medical University, Wenzhou 325000, China
Tang Yuan
School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325000, China
Chen Zhangyan
Ophthalmology and Optometry, Eye Hospital of Wenzhou Medical University, Wenzhou 325000, China
Wang Aisun
Ophthalmology and Optometry, Eye Hospital of Wenzhou Medical University, Wenzhou 325000, China
Huang Xiaoqiong
Ophthalmology and Optometry, Eye Hospital of Wenzhou Medical University, Wenzhou 325000, China
Chen Yanyan
School of Optometry and Ophthalmology, Wenzhou Medical University, Wenzhou 325000, China
Qu Jia
Ophthalmology and Optometry, Eye Hospital of Wenzhou Medical University, Wenzhou 325000, China
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Updated: June 24, 2020 — 11:24 am