Faculty of Medicine, Ophthalmology Department, Okan University, İstanbul, Turkey.
Department of Bioproducts and Biotechnology, Aalto University, Espoo, Finland.
Graefes Arch Clin Exp Ophthalmol. 2020 Oct;258(10):2275-2282. doi: 10.1007/s00417-020-04815-4. Epub 2020 Jun 25.
Microscale droplets act as coronaviruses (CoV) carriers in the air when released from an infected person and may infect others during close contact such as ophthalmic examination. The main objective of the present work is to demonstrate how CoV deposited droplets are projected during biomicroscopy and to discuss what kind of precautions should be taken in ophthalmic practice.
A coupled fluid-structure system comprising smoothed particle hydrodynamics and the finite element method has been built to assess the projection of droplets spreading from an infected person. Different conditions based on the maximum exit flow velocity from the infector's mouth during the ophthalmic examination were modeled.
During exhalation, for which the exit flow is ~ 1000 mm/s, the average horizontal distance of the flow front was ~ 200 mm while individual particles can reach up to ~ 500 mm. In case of coughing or sneezing (corresponding to an exit flow of ~ 12,000 mm/s), the average horizontal distance of the flow front was ~ 1300 mm.
During the ophthalmic examination, the proximity to the patient's nose and mouth was observed to be less than the horizontal distance of flow front particles. Even though mounted breath shields are used, particles flew beyond the shield and contaminate the ophthalmologist. Compared with the current protective breath shields, the use of a larger shield with a minimum radius of 18 cm is needed to decrease viral transmission.
感染者释放的微尺度液滴在空气中可充当冠状病毒（CoV）的载体，在近距离接触（如眼科检查）时可能会感染他人。本研究的主要目的是展示在生物显微镜下 CoV 沉积液滴是如何被喷射出来的，并讨论在眼科实践中应采取何种预防措施。
构建了一个包含光滑粒子流体动力学和有限元法的流固耦合系统，以评估从感染者传播的液滴的喷射情况。基于在眼科检查期间感染者口腔内最大出口流速，模拟了不同条件。
在呼气时（出口流速约为 1000mm/s），流前锋的平均水平距离约为 200mm，而个别颗粒可达到约 500mm。在咳嗽或打喷嚏时（出口流速约为 12000mm/s），流前锋的平均水平距离约为 1300mm。
在眼科检查过程中，观察到与患者口鼻的距离小于流前锋颗粒的水平距离。即使使用了安装的呼吸防护屏，颗粒仍会飞出击中防护屏并污染眼科医生。与当前的防护呼吸屏相比，需要使用最小半径为 18cm 的更大的防护屏，以减少病毒传播。
