Human Lacrimal Production Rates from Modified Schirmer-Tear Test

Li, Songhao; Kim, Young Hyun; Li, Wing; Lin, Meng C.; Radke, Clayton J.

doi:10.1097/opx.0000000000001196

Cited by 11 publications

(25 citation statements)

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“…Eliminating the tear reservoir in the fornix would enable more accurate measurement of tear secretion. Using the geometry of the strip and the porosity of the wetted region of the strip [13], tear meniscus volume can be calculated [24], although this was not done in this study. SM self-examination is a fast, simple and non-invasive method.…”

Section: Discussionmentioning

confidence: 99%

Diurnal variation of human tear meniscus volume measured with tear strip meniscometry self-examination

et al. 2019

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Tear secretion is critical for maintenance of healthy ocular surface and vision. Most of normal subjects and dry eye patients feel worsening of ocular dryness in the afternoon, however, diurnal variation of tear meniscus volume has not been directly measured because there was no appropriate method. We used a simple, non-invasive technique, tear strip meniscometry (SM) by self-examination. Previous investigations indicated the values of SM correlated strongly with those of the Schirmer test, tests of tear break up time, and tear meniscus height measurement by anterior optical coherence tomography. The purpose of this study was to capture diurnal variation of aqueous availability at the tear meniscus by measuring wetted length using SM through self-examination. Methods Thirty-six medical personnel (mean age; 35.7 years) participated and SM self-examination was performed using a mirror seven times a day. The strip is applied for 5 seconds to the lateral side of the lower lid tear meniscus without touching the ocular surface. Results The measured SM value was the highest upon awakening (4.44 ± 3.14 mm) and gradually decreased in the evening; 3.81

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Section: Discussionmentioning

confidence: 99%

Diurnal variation of human tear meniscus volume measured with tear strip meniscometry self-examination

et al. 2019

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“…In healthy individuals, the human tear system lubricates the eye at flow rates from 2 to 5 µL/min [20][21][22], with tear film breaking down at times normally lasting from 10 to 15 s [23,24]. In individuals suffering of severe dry eye syndrome, the tear film tends to evaporate in less than a second [23,25], causing a permanent burning sensation, and consequently a critical decrease in vision and life quality.…”

Section: Introductionmentioning

confidence: 99%

Control System Applied to the Microinjection of Artificial Tears for Severe Dry Eye Treatment

Meni-Babakidi¹,

Viramontes-Gamboa²,

Ibarra-Bracamontes³

et al. 2020

Applied Sciences

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This paper presents a portable automated teardrop microinjection system as a practical solution for patients suffering from severe dry eye. The electronic device for the controlled and continuous injection of artificial tears is designed, assembled, and tested for performance and stability. It is controlled via Wi-Fi from an Android programmable device. Its design is based on the physicochemical properties of artificial tears, and with both production costs and portability in mind. The system was modeled according to the V methodology of the association for professional German engineers VDI 2206 standard. The microinjector handles a wide range of internal variables such as tears flow rate (0.13 to 60 μL/min), tears viscosity (up to 600 Pa·s), temperature (up to 60 °C), injected volume of tears, and time between consecutive injections. For evaluation purposes, a comprehensive set of experimental tests were carried out to the system, comparing the actually delivered amount of tears, flow rate, and prescribed time vs. programmed values, the error was ∼0.2% for commercially available artificial tears.

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“…This assumption, however, may reflect incomplete understanding of what the test actually assesses. Recent studies highlight two issues that contribute to STT performance 3,4…”

Section: Introductionmentioning

confidence: 99%

“…The first issue addresses whether the traditional STT measures only the basal tear production or whether it also measures some degree of residual reflex tearing and/or uptake from the tear meniscus. There are two reported phases during an STT: rapid wetting upon initial insertion, followed by a slower, typically linear, increase with time 4. In the traditional STT without anesthetic, this observation is attributed to rapid initial wetting by reflex tearing upon strip insertion, followed by slower wetting due to basal tear production and diminished reflex tearing 5–8.…”

Section: Introductionmentioning

confidence: 99%

“…In the traditional STT without anesthetic, this observation is attributed to rapid initial wetting by reflex tearing upon strip insertion, followed by slower wetting due to basal tear production and diminished reflex tearing 5–8. Li et al,4 however, observed significant variability in the initial wetting phase even though the eyes had been anesthetized with two drops of proparacaine, an anesthetic that should nullify most or all reflex tearing 9. Based on this observation, the authors argued that in addition to reflex tear production, the initial wetting phase is influenced by the preexisting tear reservoir behind the lower lid 4.…”

Section: Introductionmentioning

confidence: 99%

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Human Lacrimal Production Rate and Wetted Length of Modified Schirmer's Tear Test Strips

Kim

Graham

et al. 2019

Trans. Vis. Sci. Tech.

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Purpose To assess and compare the wetting kinetics of sheathed and unsheathed Schirmer's tear test (STT) strips, and to determine the repeatability of 5-minute wetted length (WL) and basal tear production rate (BTPR). Methods Seventeen subjects underwent two sheathed and unsheathed STTs each for both eyes on four visits on separate days. After administration of topical anesthetic, WLs were measured every 30 seconds for 5 minutes, and BTPRs were calculated for sheathed strips. Limits of agreement (LoA), difference-versus-mean plots (DVM), and the coefficient of repeatability (CR) assessed WL and BTPR repeatabilities. Variance estimates were used to calculate sample sizes for future study. Results For the unsheathed STT, the mean (SD) difference in WLs between visits was 0.74 (5.05) mm, LoA were [−9.17, 10.64], and CR was 9.17 mm; for the sheathed STT, the mean (SD) intervisit difference was 0.16 (5.94) mm, LoA were [−11.49, 11.8], and CR was 10.53 mm. Eight of 48 sheathed STTs and 20 of 44 unsheathed STTs showed constant WL for the final 90 seconds of the test. The mean (SD) difference between repeated visits for BTPR was approximately 0.0 μL/min, LoA were [−1.82, 1.82], and CR was 1.91 μL/min. Conclusions Repeatability of sheathed and unsheathed 5-minute WL and BTPR is inadequate for measuring within-subject changes, but is sufficient for group studies with moderate sample sizes. Constant WL for the final 90 seconds with the eight sheathed STT measurements suggests varying BTPR, whereas constant WL with the unsheathed STT can be explained by balancing evaporation and BTPR. Translational Relevance Repeatability of the modified STT is evaluated clinically to establish quantitative BTPRs rather than inference from a strip WL.

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Human Lacrimal Production Rates from Modified Schirmer-Tear Test

Cited by 11 publications

References 20 publications

Diurnal variation of human tear meniscus volume measured with tear strip meniscometry self-examination

Diurnal variation of human tear meniscus volume measured with tear strip meniscometry self-examination

Control System Applied to the Microinjection of Artificial Tears for Severe Dry Eye Treatment

Human Lacrimal Production Rate and Wetted Length of Modified Schirmer's Tear Test Strips

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