Effect of Intraocular Pressure on Aerosol Density Generated by Noncontact Tonometer Measurement

Tang, Yuan Yan; Li, Chunchun; Chen, Yanyan; Chen, Zhangyan; Zhang, Peihua; Wang, Aisun; Huang, Xiaoqiong; Qu, Jia; Li, Mengchen; Ma, Siwen; Vasudevan, Balamurali

doi:10.1097/ijg.0000000000001669

Cited by 11 publications

(18 citation statements)

References 10 publications

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“…A previous study claimed that the IOP level might affect the concentration of generated aerosols. 13 As the binocular IOP difference was insignificant in our subjects, the PM concentration we recorded after NCT measurement of both eyes would not be affected. Our result indicated the local accumulation of aerosol on the lateral side of NCT, which can be applied to both eyes.…”

Section: Discussionmentioning

confidence: 66%

“…The accuracy and intra-model variability of such device has been presented by the Air Quality Sensor Performance Evaluation Center (AQ-SPEC) program, 17,18 and the device was also applied in the previous studies. 13,14 It was detected by a built-in laser particulate sensor and numerically displayed in the form of PM concentration. The measuring range of PM concentration was 0-999 μg/m 3 with a resolution of 0.1 μg/m 3 .…”

Section: Interventions and Outcomesmentioning

confidence: 99%

“…11 Meanwhile, similar to tear droplets, the production of aerosol with smaller particle diameter was also increased. [12][13][14] Binding to aerosol, the virus particle may gain prolonged existence and increasing distance of spread. 15 As the aerosol dispersion has been considered a potential route of COVID-19 transmission, 15 both the patients and operators may suffer the risk of exposure during the IOP measurement.…”

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confidence: 99%

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Assessment of temporal and spatial distribution patterns of aerosol produced by air-puff non-contact tonometer

Chen

Zhang

2021

European Journal of Ophthalmology

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Purpose To assess the distribution pattern of aerosol in the aspect of time and direction during the intraocular pressure (IOP) measurement by air-puff non-contact tonometer (NCT) and further offer references for protection from coronavirus disease-19 (COVID-19) in the routine ophthalmic examination. Method A single-center observational study was conducted in the ophthalmology clinics of Peking University Third Hospital. Two air quality detectors were equipped to assess the generated particulate matter (PM) concentration simultaneously within 30 s after IOP measurement in the outpatient hall. Detector A was fixed next to the NCT as a reference, while Detector B was fixed 1 meter away. The participants were divided into two groups depending on the position of Detector B. The generation of aerosol was compared within different groups and time intervals. Results 144 participants were enrolled in the final analysis. At a 1 m distance from the NCT, the PM2.5 concentration significantly increased at the 30 s ( Z = 2.898, Bonferroni-corrected P = 0.038) while the PM10 concentration increased immediately after the IOP measurement ( Z = 2.967, Bonferroni-corrected P = 0.030). The PM2.5 and PM10 concentrations at 1 m were significantly higher immediately ( Z = −2.183, P = 0.029; Z = −2.502, P = 0.012) and 30 s ( Z = −2.021, P = 0.043; Z = −2.071, P = 0.038) after the IOP measurements when the Detector B was vertical to the air jet on the lateral side. Conclusions NCT may produce aerosol after the IOP measurement by air-puff. The generated PM2.5 had a prolonged existence compared with PM10 at a 1 m distance. The lateral side of the air-puff direction may be of higher exposure risk to aerosol.

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Section: Discussionmentioning

confidence: 66%

Section: Interventions and Outcomesmentioning

confidence: 99%

mentioning

confidence: 99%

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Assessment of temporal and spatial distribution patterns of aerosol produced by air-puff non-contact tonometer

Chen

Zhang

2021

European Journal of Ophthalmology

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“…Recent studies have suggested the potential for aerosolization of the tear film with NCTs which would pose a risk with the clinical use of these devices during this pandemic with concern of possible viral load in the tears. 11 – 13 However, the instructions for caution have been controversial and other research groups have contradicted such findings, indicating that NCTs do not generate droplets unless eye drops are given prior to the examination. 14 , 15 Given the recent emergence of several COVID-19 mutations, which reportedly have a higher infectious rate, as well as increasing evidence that the major disease transmission route is airborne, it is timely to characterize the potential for droplet formation with these devices.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Interaction Between Tear Film and Air Puff From Noncontact Tonometry

Yousefi

Roberts

et al. 2022

Trans. Vis. Sci. Tech.

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Purpose The purpose of this study was to investigate the mechanism of potential droplet formation in response to air puff deformation with two noncontact tonometers (NCTs). Methods Twenty healthy volunteers were examined using two NCTs, Ocular Response Analyzer and Corvis ST, and two contact tonometers, iCare and Tono-Pen. High-speed videos of the tear film response were captured with at spatial resolution of 20 microns/pixel at 2400 fps. Droplet size, droplet velocity, distance between air puff impact location, and the tear meniscus-lid margin were characterized. Results One subject was excluded due to technical issues. Droplets were detected only in tests with instilled eye drop. Videos showed the tear film rolls away from the apex while remaining adherent to the ocular surface due to the tendency of the fluid to remain attached to a solid surface explained by the Coanda effect. Twelve out of 38 videos with an eye drop administration showed droplet formation. Only one resulted in droplets with predominantly forward motion, which had the shortest distance between air puff impact location and lower meniscus. This distance on average was 5.9 ± 1.1 mm. The average droplet size was 500 ± 200 µm. Conclusions Results indicate no droplet formation under typical clinical setting. Hence, standard clinical use of NCT tests is not expected to cause droplets. NCT testing with eye drop administration showed droplet formation at the inferior eyelid boundary, which acts as a barrier and interrupts tear flow. Translational Relevance Study of tear film interaction with NCT air puff shows that these tonometers are not expected to cause droplet formation in standard use and that if external drops are required, both eyelids should be held if patients need assistance to maintain open eyes to avoid droplets with predominantly forward motion.

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“…16 Many studies have shown good correlation of CCT readings between USP and anterior segment optical coherence tomography (AS-OCT) regardless of the corneal thickness; [17][18][19][20] therefore, researchers tend to use noncontact methods. 16 Moreover, the transmissibility of the Coronavirus disease 2019 (COVID-19) from the ocular surface remains indefinite; thus, contact and aerosol-generating procedures are best avoided to prevent transmission, particularly among eyes with high IOP 21 and high tear volume. 22 Thin CCT underestimates IOP, while thick CCT overestimates IOP.…”

Section: Introductionmentioning

confidence: 99%

Central Corneal Thickness Among Filipino Patients in an Ambulatory Eye Surgery Center Using Anterior Segment Optical Coherence Tomography

Sosuan¹,

Yap-Veloso²

2021

OPTH

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Objective The purpose of the study was to determine the central corneal thickness (CCT) among Filipino patients that may contribute to different glaucoma diagnosis using the anterior segment optical coherence tomography in an ambulatory eye surgery center. Methods A single-center retrospective, cross-sectional study design including 1232 eyes of 641 patients of the Asian Eye Institute, Makati, Philippines from January 2019 to December 2019 who had their CCT measured with Visante anterior segment optical coherence tomography (AS-OCT). CCT was correlated with age, sex, presence of diabetes and/or hypertension, and glaucoma diagnosis. Results Among 641 patients who had their CCT measured by Visante AS-OCT, 723 eyes of 369 patients were included. Nearly half of the study population were normal or glaucoma suspects. The mean CCT among Filipino patients was 535.59 ± 34.06 µm. Ocular hypertensive patients had the thickest CCT, while normal tension glaucoma patients had the thinnest CCT. After adjusting for multiple variables, CCT had a direct relationship with the presence of diabetes, IOP level and the diagnosis of ocular hypertension, while inverse relationship with age. Most of the patients presenting with angle closure glaucoma were females aged 60 and above. Conclusion Visante AS-OCT is a non-contact and non-aerosol generating instrument allaying the fear of disease transmission from contact or aerosolization of tears. Our study confirms similar relationships of CCT with age, presence of diabetes, IOP level, and diagnosis of ocular hypertension or normal tension glaucoma among Filipino patients with the available literature from other ethnicities.

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Effect of Intraocular Pressure on Aerosol Density Generated by Noncontact Tonometer Measurement

Cited by 11 publications

References 10 publications

Assessment of temporal and spatial distribution patterns of aerosol produced by air-puff non-contact tonometer

Assessment of temporal and spatial distribution patterns of aerosol produced by air-puff non-contact tonometer

Hydrodynamic Interaction Between Tear Film and Air Puff From Noncontact Tonometry

Central Corneal Thickness Among Filipino Patients in an Ambulatory Eye Surgery Center Using Anterior Segment Optical Coherence Tomography

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