Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China.
State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, China.
Adv Ther. 2021 Jun;38(6):3066-3076. doi: 10.1007/s12325-021-01740-8. Epub 2021 Apr 28.
Ophthalmologists are inevitably exposed to tears and ocular discharge during ophthalmologic examinations and are at high risk for SARS-CoV-2 infection. To understand the role of aerosols in disease transmission, we adopted a prospective cross-sectional study design and investigated the count and size distribution of aerosols generated by a non-contact tonometer and its correlation with individual tear film characteristics.
This study constituted two parts. The study population included outpatients who underwent an intraocular pressure examination in an intraocular pressure examination room (Part I) and 20 participants who underwent an intraocular pressure examination in a laboratory (Part II). The following main outcomes were measured: aerosol counts at 0, 50, 100, 150, and 200 cm from the non-contact tonometer (Part I); aerosol counts after each participant underwent non-contact tonometry, and lipid layer thickness score and tear film break-up time (Part II).
The aerosol count decreased with increasing distance from the tonometer. The aerosol count at 0 cm had the highest value compared to that at other distances. For aerosols of diameters 0.25-0.5 μm and 0.5-1.0 μm, the count decreased at 50 cm and remained stable at further distances. For aerosols of diameters 1.0-2.5 μm and ≥ 2.5 μm, the count dropped progressively at all five distances. The aerosol count from each tonometer correlated positively with the lipid layer thickness score (r = 0.490, P = 0.028), whereas the aerosol count correlated negatively with the tear film break-up time (r = - 0.675, P = 0.001).
Aerosols tended to coagulate during diffusion. A 50-cm distance from the tonometer could confer safety from aerosols with < 1.0-μm diameter. Aerosols generated during non-contact tonometry could contain a lipid layer component. Moreover, tear film stability could affect aerosol generation. Protective eyewear is recommended for reducing infection risk from aerosols. Individual tear film characteristics should be considered during non-contact tonometry.
眼科医生在眼科检查中不可避免地会接触到眼泪和眼分泌物，因此感染 SARS-CoV-2 的风险很高。为了了解气溶胶在疾病传播中的作用，我们采用了前瞻性的横断面研究设计，研究了非接触眼压计产生的气溶胶的计数和粒径分布及其与个体泪膜特征的相关性。
本研究分为两部分。研究人群包括在眼压检查室接受眼压检查的门诊患者（第 I 部分）和 20 名在实验室接受眼压检查的参与者（第 II 部分）。主要测量结果如下：非接触眼压计 0、50、100、150 和 200 cm 处的气溶胶计数（第 I 部分）；每位参与者接受非接触眼压计测量后的气溶胶计数以及脂质层厚度评分和泪膜破裂时间（第 II 部分）。
气溶胶计数随与眼压计距离的增加而降低。与其他距离相比，0 cm 处的气溶胶计数最高。对于 0.25-0.5 μm 和 0.5-1.0 μm 的气溶胶，在 50 cm 处计数降低，在更远的距离保持稳定。对于 1.0-2.5 μm 和≥2.5 μm 的气溶胶，在所有五个距离处都呈逐渐下降趋势。每个眼压计的气溶胶计数与脂质层厚度评分呈正相关（r=0.490，P=0.028），而气溶胶计数与泪膜破裂时间呈负相关（r=-0.675，P=0.001）。
气溶胶在扩散过程中趋于凝聚。距离眼压计 50 cm 处可确保安全，避免吸入直径<1.0-μm 的气溶胶。非接触眼压计产生的气溶胶可能含有脂质层成分。此外，泪膜稳定性会影响气溶胶的产生。建议佩戴防护眼镜以降低气溶胶感染风险。在进行非接触眼压测量时应考虑个体泪膜特征。
