1
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Kim YH, Lee J, Yi SM, Lin MC, Radke CJ. Localized Evaporative Cooling Explains Observed Ocular Surface-Temperature Patterns. Invest Ophthalmol Vis Sci 2024; 65:15. [PMID: 39110586 PMCID: PMC11314627 DOI: 10.1167/iovs.65.10.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2024] [Accepted: 07/18/2024] [Indexed: 08/11/2024] Open
Abstract
Purpose We determined interblink corneal surface-temperature decline and tear-film evaporation rates of localized tear breakup cold regions (LCRs) and localized tear unbroken warm regions (LWRs) of the corneal surface, as well as that of the overall average corneal surface. Methods Each subject underwent 4 inter-day visits where the interblink corneal surface-temperature history of the right eye was measured using a FLIR A655sc infrared thermographer. Corneal surface temperature history was analyzed to determine the overall, LCR, and LWR temperature-decline rates. Evaporation rates of LCR and LWR regions were determined from the measured LCR and LWR temperature data using the physical model of Dursch et al. Results Twenty subjects completed the study. Mean (SD) difference of LCR temperature-decline rate was -0.08 (0.07)°C/s faster than LWR (P < 0.0001). Similarly, evaporation rates of LCR and LWR were statistically different (P < 0.0001). At ambient temperature, mean LCR and LWR evaporation rates were 76% and 27% of pure water evaporation flux, respectively. There was no statistically significant difference between the inter-day measured temperature-decline rates and the interblink starting temperature. Conclusions Significant differences in corneal temperature-decline rate and evaporation rate between LCR and LWR were quantified using infrared thermography. In agreement with literature, LCRs and LWRs correlate directly with fluorescein break-up areas and unbroken tear areas, respectively. Because lipid-evaporation protection is diminished in breakup areas, higher local evaporation rates and faster local cooling rates occur in LCRs relative to LWRs. Our results confirm this phenomenon clinically for the first time.
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Affiliation(s)
- Young Hyun Kim
- Herbert Wertheim School of Optometry & Vision Science, University of California – Berkeley, Berkeley California, United States
- Chemical and Biomolecular Engineering Department, University of California – Berkeley, Berkeley, California, United States
- Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California – Berkeley, Berkeley, California, United States
| | - Joshua Lee
- Chemical and Biomolecular Engineering Department, University of California – Berkeley, Berkeley, California, United States
| | - Sarah M. Yi
- Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California – Berkeley, Berkeley, California, United States
- Department of Medicine, Emory School of Medicine, Emory University, Atlanta, Georgia, United States
| | - Meng C. Lin
- Herbert Wertheim School of Optometry & Vision Science, University of California – Berkeley, Berkeley California, United States
- Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California – Berkeley, Berkeley, California, United States
| | - Clayton J. Radke
- Herbert Wertheim School of Optometry & Vision Science, University of California – Berkeley, Berkeley California, United States
- Chemical and Biomolecular Engineering Department, University of California – Berkeley, Berkeley, California, United States
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2
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Yeh CH, Graham AD, Yu SX, Lin MC. Enhancing Meibography Image Analysis Through Artificial Intelligence-Driven Quantification and Standardization for Dry Eye Research. Transl Vis Sci Technol 2024; 13:16. [PMID: 38904611 PMCID: PMC11193141 DOI: 10.1167/tvst.13.6.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 05/15/2024] [Indexed: 06/22/2024] Open
Abstract
Purpose This study enhances Meibomian gland (MG) infrared image analysis in dry eye (DE) research through artificial intelligence (AI). It is comprised of two main stages: automated eyelid detection and tarsal plate segmentation to standardize meibography image analysis. The goal is to address limitations of existing assessment methods, bridge the curated and real-world dataset gap, and standardize MG image analysis. Methods The approach involves a two-stage process: automated eyelid detection and tarsal plate segmentation. In the first stage, an AI model trained on curated data identifies relevant eyelid areas in non-curated datasets. The second stage refines the eyelid area in meibography images, enabling precise comparisons between normal and DE subjects. This approach also includes specular reflection removal and tarsal plate mask refinement. Results The methodology achieved a promising instance-wise accuracy of 80.8% for distinguishing meibography images from 399 DE and 235 non-DE subjects. By integrating diverse datasets and refining the area of interest, this approach enhances meibography feature extraction accuracy. Dimension reduction through Uniform Manifold Approximation and Projection (UMAP) allows feature visualization, revealing distinct clusters for DE and non-DE phenotypes. Conclusions The AI-driven methodology presented here quantifies and classifies meibography image features and standardizes the analysis process. By bootstrapping the model from curated datasets, this methodology addresses real-world dataset challenges to enhance the accuracy of meibography image feature extraction. Translational Relevance The study presents a standardized method for meibography image analysis. This method could serve as a valuable tool in facilitating more targeted investigations into MG characteristics.
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Affiliation(s)
- Chun-Hsiao Yeh
- Vision Science Group, Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
- Electrical Engineering and Computer Science, University of California, Berkeley, Berkeley, CA, USA
- Clinical Research Center, Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
| | - Andrew D. Graham
- Vision Science Group, Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
- Clinical Research Center, Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
| | - Stella X. Yu
- Electrical Engineering and Computer Science, University of California, Berkeley, Berkeley, CA, USA
- Computer Science and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Meng C. Lin
- Vision Science Group, Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
- Clinical Research Center, Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
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3
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Gu Z, Cao G, Wu C, Huang Y, Xu B, Zhuang S, Li B. Comparing the ocular surface temperature and dry eye condition of keratoconus with normal eyes using infrared thermal imaging. Int Ophthalmol 2023; 43:4781-4789. [PMID: 37695496 DOI: 10.1007/s10792-023-02878-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 08/26/2023] [Indexed: 09/12/2023]
Abstract
PURPOSE This study was conducted to compare the ocular surface temperature in keratoconus eyes with that in normal eyes. METHODS A total of 27 participants were enrolled, with 10 and 17 participants in the keratoconus and control groups, respectively. Participants in the control group underwent an ophthalmic slit lamp examination and ocular thermography, while an additional corneal tomography was performed for those in the keratoconus group. RESULTS For patients with keratoconus, the mean upper eyelid temperature (UET) was 32.36 ± 1.02 °C, inner canthus temperature (ICT) was 34.25 ± 0.83 °C, outer canthus temperature (OCT) was 33.62 ± 0.96 °C, initial central corneal temperature (initial CCT) was 33.04 ± 1.03 °C, sixth-second CCT (6 s-CCT) was 32.67 ± 1.19 °C, and the mean change in CCT measured within 6 s (change in CCT within 6 s) was 0.36 ± 0.26 °C. For controls, the values for UET, ICT, OCT, initial CCT, 6 s-CCT, and change in CCT within 6 s were 32.35 ± 1.13 °C, 34.14 ± 0.91 °C, 33.51 ± 1.02 °C, 33.22 ± 1.01 °C, 32.99 ± 1.01 °C, and 0.22 ± 0.17 °C, respectively. Except for the change in CCT within 6 s (p = 0.022), no significant differences were observed in UET (p = 0.973), ICT (p = 0.659), OCT (p = 0.697), initial CCT (p = 0.556) or 6 s-CCT (p = 0.310) between the two groups. CONCLUSION The keratoconus eyes showed faster changes in CCT and evaporation of tear film after opening the eyes. Therefore, the keratoconus eyes had a higher incidence of dry eye conditions.
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Affiliation(s)
- Zhensheng Gu
- Department of Ophthalmology, School of Medicine, Xinhua Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Guofan Cao
- Affiliated Eye Hospital of Nanjing Medical University, Nanjing, China
| | - Chunbo Wu
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Yuanshen Huang
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Banglian Xu
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Songlin Zhuang
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, China
| | - Baicheng Li
- School of Optical Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai, China.
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4
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Kim YH, Graham AD, Li W, Dursch TJ, Peng CC, Radke CJ, Lin MC. Tear-film evaporation flux and its relationship to tear properties in symptomatic and asymptomatic soft-contact-lens wearers. Cont Lens Anterior Eye 2023; 46:101850. [PMID: 37137757 DOI: 10.1016/j.clae.2023.101850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 02/18/2023] [Accepted: 04/17/2023] [Indexed: 05/05/2023]
Abstract
PURPOSE With soft-contact-lens wear, evaporation of the pre-lens tear film affects the osmolarity of the post-lens tear film and this can introduce a hyperosmotic environment at the corneal epithelium, leading to discomfort. The purposes of the study are to ascertain whether there are differences in evaporation flux (i.e., the evaporation rate per unit area) between symptomatic and asymptomatic soft-contact-lens wearers, to assess the repeatability of a flow evaporimeter, and to assess the relationship between evaporation fluxes, tear properties, and environmental conditions. METHODS Closed-chamber evaporimeters commonly used in ocular-surface research do not control relative humidity and airflow, and, therefore, misestimate the actual tear-evaporation flux. A recently developed flow evaporimeter overcomes these limitations and was used to measure accurate in-vivo tear-evaporation fluxes with and without soft-contact-lens wear for symptomatic and asymptomatic habitual contact-lens wearers. Concomitantly, lipid-layer thickness, ocular-surface-temperature decline rate (i.e., °C/s), non-invasive tear break-up time, tear-meniscus height, Schirmer tear test, and environmental conditions were measured in a 5 visit study. RESULTS Twenty-one symptomatic and 21 asymptomatic soft-contact-lens wearers completed the study. A thicker lipid layer was associated with slower evaporation flux (p < 0.001); higher evaporation flux was associated with faster tear breakup irrespective of lens wear (p = 0.006). Higher evaporation flux was also associated with faster ocular-surface-temperature decline rate (p < 0.001). Symptomatic lens wearers exhibited higher evaporation flux than did asymptomatic lens wearers, however, the results did not reach statistical significance (p = 0.053). Evaporation flux with lens wear was higher than without lens wear but was also not statistically significant (p = 0.110). CONCLUSIONS The repeatability of the Berkeley flow evaporimeter, associations between tear characteristics and evaporation flux, sample-size estimates, and near statistical significance in tear-evaporation flux between symptomatic and asymptomatic lens wearers all suggest that with sufficient sample sizes, the flow evaporimeter is a viable research tool to understand soft-contact-lens wear comfort.
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Affiliation(s)
- Young Hyun Kim
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720, United States
| | - Andrew D Graham
- Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States
| | - Wing Li
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States
| | - Thomas J Dursch
- Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720, United States
| | - Cheng-Chun Peng
- Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720, United States; CooperVision Inc., Pleasanton, CA 94588, United States
| | - Clayton J Radke
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720, United States
| | - Meng C Lin
- Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States; Clinical Research Center, Herbert Wertheim School of Optometry & Vision Science, University of California, Berkeley, CA 94720, United States.
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5
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Monfared N, Murphy PJ. Features and influences on the normal tear evaporation rate. Cont Lens Anterior Eye 2023; 46:101809. [PMID: 36621341 DOI: 10.1016/j.clae.2022.101809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 12/23/2022] [Accepted: 12/28/2022] [Indexed: 01/09/2023]
Abstract
Tear evaporation is a normal physiological phenomenon that has an important role in regulating blink activity and tear production. An altered tear evaporation rate (TER) is a defining characteristic of evaporative dry eye disease (DED), and the measurement of tear evaporation is a useful clinical test for diagnosis. Reported values for a normal TER cover a broad range, which may be due to the influence of ocular, environmental, and systemic factors. For improved disease diagnosis, a fuller understanding of the normal TER range is essential. This paper reports on a literature review of the current knowledge of these normal influences on TER.
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Affiliation(s)
- Naeimeh Monfared
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada.
| | - Paul J Murphy
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
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6
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Sheppard JD, Nichols KK. Dry Eye Disease Associated with Meibomian Gland Dysfunction: Focus on Tear Film Characteristics and the Therapeutic Landscape. Ophthalmol Ther 2023; 12:1397-1418. [PMID: 36856980 PMCID: PMC10164226 DOI: 10.1007/s40123-023-00669-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/27/2023] [Indexed: 03/02/2023] Open
Abstract
Meibomian gland dysfunction (MGD) is highly prevalent and is the leading cause of evaporative dry eye disease (DED). MGD is characterized by a reduction in meibum secretion and/or a change in meibum composition that results in the disruption of the tear film lipid layer and an increase in the tear film evaporation rate. Excessive evaporation causes tear film instability, desiccation, tear hyperosmolarity, inflammation, and apoptosis of ocular surface cells, resulting in a continuous cycle of DED. The primary treatment goal for DED associated with MGD is to restore the tear film lipid layer and decrease evaporation, thereby reducing ocular signs and symptoms. The management of MGD includes home care options (eyelid hygiene, warming eye masks, ocular lubricants) and office-based treatments (manual expression, microblepharoexfoliation, thermal pulsation, intense pulsed light, intraductal probing). Topical ophthalmic prescription medications attempt to alter various factors that may contribute to DED (e.g., inflammation, bacterial growth, inadequate tear production). In this review, clinical evidence regarding available treatments and emerging therapies from randomized studies in patients with DED associated with MGD is summarized. Although some treatment modalities have been evaluated specifically for DED patients with MGD, large-scale randomized controlled trials are needed to confirm efficacy and safety in this patient population. Currently, there are no approved prescription pharmacologic treatments specifically indicated for DED associated with MGD, and those medications approved for the treatment of DED do not target the key driver of the disease (i.e., excessive evaporation). NOV03 (perfluorohexyloctane; under review with the US Food and Drug Administration) is the most advanced emerging therapy for DED associated with MGD and has demonstrated statistically significant improvements in both signs and symptoms in randomized controlled trials. Development of novel pharmacotherapies will improve therapeutic options and allow for a more individualized approach for patients with DED associated with MGD.
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Affiliation(s)
- John D Sheppard
- Virginia Eye Consultants and Eastern Virginia Medical School, Suite #210, 241 Corporate Blvd, Norfolk, VA, 23502, USA. .,Eyecare Partners, St. Louis, MO, USA.
| | - Kelly K Nichols
- School of Optometry, University of Alabama at Birmingham, Birmingham, AL, USA
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7
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Xu X, Li G, Zuo YY. Effect of Model Tear Film Lipid Layer on Water Evaporation. Invest Ophthalmol Vis Sci 2023; 64:13. [PMID: 36656568 PMCID: PMC9872843 DOI: 10.1167/iovs.64.1.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Purpose A majority of in vitro models were incapable of reproducing the evaporation resistance of tear film lipid layer (TFLL) in vivo. The purpose of this research is to develop a novel in vitro model to study the effect of TFLL on water evaporation. Methods A ventilated, closed-chamber, droplet evaporimeter with a constant surface area has been invented to study the evaporation resistance of TFLL. This evaporimeter ensures a rigorous control of environmental conditions, including the temperature, relative humidity, airflow rate, surface area, and surface pressure, thus allowing for reproducible water evaporation measurements over a time period of only 5 minutes. The volumetric evaporation rate of this droplet evaporimeter is less than 2.7 µL/min, comparable to the basal tear production of healthy adults. Together with direct film imaging using atomic force microscopy (AFM), we have studied the effect of a model TFLL on water evaporation, as a function of the lipid composition and surface pressure. Results A model TFLL composed of 40% wax esters, 40% cholesteryl esters, and 20% polar lipids was capable of reducing the water evaporation rate by 11% at surface pressure 47 mN/m. AFM revealed that the model TFLL at high surface pressures consists of discrete droplets/aggregates of the nonpolar lipids residing atop a polar lipid monolayer with phase separation. Conclusions The TFLL may resist water evaporation with a combined mechanism by increasing film compactness of the polar lipid film at the air-water surface, and, to a lesser extent, by increasing film thickness of the nonpolar lipid film.
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Affiliation(s)
- Xiaojie Xu
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii, United States
| | - Guangle Li
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii, United States
| | - Yi Y. Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii, United States,Department of Pediatrics, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, United States
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8
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Predicting demographics from meibography using deep learning. Sci Rep 2022; 12:15701. [PMID: 36127431 PMCID: PMC9489726 DOI: 10.1038/s41598-022-18933-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/22/2022] [Indexed: 11/08/2022] Open
Abstract
This study introduces a deep learning approach to predicting demographic features from meibography images. A total of 689 meibography images with corresponding subject demographic data were used to develop a deep learning model for predicting gland morphology and demographics from images. The model achieved on average 77%, 76%, and 86% accuracies for predicting Meibomian gland morphological features, subject age, and ethnicity, respectively. The model was further analyzed to identify the most highly weighted gland morphological features used by the algorithm to predict demographic characteristics. The two most important gland morphological features for predicting age were the percent area of gland atrophy and the percentage of ghost glands. The two most important morphological features for predicting ethnicity were gland density and the percentage of ghost glands. The approach offers an alternative to traditional associative modeling to identify relationships between Meibomian gland morphological features and subject demographic characteristics. This deep learning methodology can currently predict demographic features from de-identified meibography images with better than 75% accuracy, a number which is highly likely to improve in future models using larger training datasets, which has significant implications for patient privacy in biomedical imaging.
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9
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King-Smith PE, Begley C, Braun RJ. A Perspective on the Use of Fluorescent Imaging to Reveal Mechanisms of Breakup. Curr Eye Res 2022; 47:1355-1361. [PMID: 35861694 DOI: 10.1080/02713683.2022.2098981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Purpose: Tear film instability, which can lead to rapid tear film breakup (TBU), is considered to be a major etiological factor in dry eye. However, experimental support for many of the proposed theories for TBU mechanisms is relatively scarce. The major aim of this perspective is to show that fluorescence studies of TBU can be used to provide experimental evidence for two proposed underlying mechanisms of TBU, evaporation and divergent flow.Methods: To understand the effects of TBU on tear film fluorescence, we show that local fluorescence is the product of three main factors: tear film thickness, fluorescein concentration and fluorescent efficiency. In divergent tear flow, tear film thickness is reduced without change in fluorescein concentration and fluorescent efficiency, thus leading to reduced fluorescence intensity. Evaporation causes decreased fluorescence mainly by self-quenching due to high fluorescein concentration. Fluorescent efficiency is reduced by quenching at high fluorescein concentration but is independent of concentration for very low fluorescein concentration; thus, comparison of high and very low concentrations of fluorescein can be used to discriminate between divergent flow and evaporation. Finally, it is shown how the fluorescent pattern can change greatly during the development of breakup.Conclusions: This analysis demonstrates that the study of tear film fluorescence in TBU and dry eye may be underutilized as additional information pertinent to clinical practice may be obtained. A better understanding of TBU mechanisms may lead to improved diagnosis and treatment of dry eye.
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Affiliation(s)
| | - Carolyn Begley
- School of Optometry, Indiana University, Bloomington, IN, USA
| | - Richard J Braun
- Department of Mathematical Sciences, University of Delaware, Newark, DE, USA
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10
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Ding JE, Kim YH, Yi SM, Graham AD, Li W, Lin MC. Ocular surface cooling rate associated with tear film characteristics and the maximum interblink period. Sci Rep 2021; 11:15030. [PMID: 34294850 PMCID: PMC8298610 DOI: 10.1038/s41598-021-94568-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023] Open
Abstract
The surface of the human eye is covered with a protective tear film that refreshes with each blink. Natural blinking occurs involuntarily, but one can also voluntarily blink or refrain from blinking. The maximum time one can refrain from blinking until the onset of discomfort is the maximum interblink period (MIBP). During the interblink period the tear film evaporates and thins from the ocular surface. Infrared thermography provides a non-invasive measure of the ocular surface temperature (OST). Due to evaporation, ocular surface cooling (OSC) generally occurs when the eyes are open and exposed to the environment. The purpose of our study was to investigate the effect of OSC rate on the MIBP, and to investigate the association of the MIBP with tear film characteristics in subjects who do and do not exhibit OSC. The MIBP was measured simultaneously with OST over time. Non-invasive tear breakup time, tear meniscus height, tear lipid layer thickness, and Schirmer I test strip wetted lengths were measured on a day prior to the thermography visit. Subjects were divided into cooling and non-cooling groups based on OSC rate, and demographic and tear film characteristics were tested for inter-group differences. A faster OSC rate was associated with an exponentially shorter duration of the MIBP overall and within the cooling group alone. Faster non-invasive tear breakup time was significantly associated with a shorter MIBP in both groups. These results suggest that tear film evaporation initiates a pathway that results in the onset of ocular discomfort and the stimulus to blinking. The presence of a subset of subjects with no or minimal OSC who nevertheless have a short MIBP indicates that evaporative cooling is not the only mechanism responsible for the onset of ocular discomfort.
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Affiliation(s)
- Jennifer E. Ding
- grid.47840.3f0000 0001 2181 7878Clinical Research Center, School of Optometry, University of California, Berkeley, 360 Minor Hall, Berkeley, CA 94720-2020 USA
| | - Young Hyun Kim
- grid.47840.3f0000 0001 2181 7878Clinical Research Center, School of Optometry, University of California, Berkeley, 360 Minor Hall, Berkeley, CA 94720-2020 USA ,grid.47840.3f0000 0001 2181 7878Vision Science Graduate Group, University of California, Berkeley, CA 94720 USA ,grid.47840.3f0000 0001 2181 7878Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA 94720 USA
| | - Sarah M. Yi
- grid.47840.3f0000 0001 2181 7878Clinical Research Center, School of Optometry, University of California, Berkeley, 360 Minor Hall, Berkeley, CA 94720-2020 USA
| | - Andrew D. Graham
- grid.47840.3f0000 0001 2181 7878Clinical Research Center, School of Optometry, University of California, Berkeley, 360 Minor Hall, Berkeley, CA 94720-2020 USA
| | - Wing Li
- grid.47840.3f0000 0001 2181 7878Clinical Research Center, School of Optometry, University of California, Berkeley, 360 Minor Hall, Berkeley, CA 94720-2020 USA
| | - Meng C. Lin
- grid.47840.3f0000 0001 2181 7878Clinical Research Center, School of Optometry, University of California, Berkeley, 360 Minor Hall, Berkeley, CA 94720-2020 USA ,grid.47840.3f0000 0001 2181 7878Vision Science Graduate Group, University of California, Berkeley, CA 94720 USA
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11
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Luke RA, Braun RJ, Driscoll TA, Awisi-Gyau D, Begley CG. Parameter Estimation for Mixed-Mechanism Tear Film Thinning. Bull Math Biol 2021; 83:56. [PMID: 33835298 DOI: 10.1007/s11538-021-00871-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/11/2021] [Indexed: 11/29/2022]
Abstract
Etiologies of tear breakup include evaporation-driven, divergent flow-driven, and a combination of these two. A mathematical model incorporating evaporation and lipid-driven tangential flow is fit to fluorescence imaging data. The lipid-driven motion is hypothesized to be caused by localized excess lipid, or "globs." Tear breakup quantities such as evaporation rates and tangential flow rates cannot currently be directly measured during breakup. We determine such variables by fitting mathematical models for tear breakup and the computed fluorescent intensity to experimental intensity data gathered in vivo. Parameter estimation is conducted via least squares minimization of the difference between experimental data and computed answers using either the trust-region-reflective or Levenberg-Marquardt algorithm. Best-fit determination of tear breakup parameters supports the notion that evaporation and divergent tangential flow can cooperate to drive breakup. The resulting tear breakup is typically faster than purely evaporative cases. Many instances of tear breakup may have similar causes, which suggests that interpretation of experimental results may benefit from considering multiple mechanisms.
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Affiliation(s)
- Rayanne A Luke
- Department of Mathematical Sciences, University of Delaware, Newark, DE, 19716, USA.
| | - Richard J Braun
- Department of Mathematical Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Tobin A Driscoll
- Department of Mathematical Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Deborah Awisi-Gyau
- Department of Mathematical Sciences, University of Delaware, Newark, DE, 19716, USA
| | - Carolyn G Begley
- Department of Mathematical Sciences, University of Delaware, Newark, DE, 19716, USA
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Viitaja T, Raitanen JE, Moilanen J, Paananen RO, Ekholm FS. The Properties and Role of O-Acyl-ω-hydroxy Fatty Acids and Type I-St and Type II Diesters in the Tear Film Lipid Layer Revealed by a Combined Chemistry and Biophysics Approach. J Org Chem 2021; 86:4965-4976. [PMID: 33729799 PMCID: PMC8041317 DOI: 10.1021/acs.joc.0c02882] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
The tear film lipid
layer (TFLL) that covers the ocular surface
contains several unique lipid classes, including O-acyl-ω-hydroxy fatty acids, type I-St diesters, and type II
diesters. While the TFLL represents a unique biological barrier that
plays a central role in stabilizing the entire tear film, little is
known about the properties and roles of individual lipid species.
This is because their isolation from tear samples in sufficient quantities
is a tedious task. To provide access to these species in their pure
form, and to shed light on their properties, we here report a general
strategy for the synthesis and structural characterization of these
lipid classes. In addition, we study the organization and behavior
of the lipids at the air–tear interface. Through these studies,
new insights on the relationship between structural features, such
as number of double bonds and the chain length, and film properties,
such as spreading and evaporation resistance, were uncovered.
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Affiliation(s)
- Tuomo Viitaja
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.,Ophthalmology, University of Helsinki and Helsinki University Hospital, Haartmaninkatu 8, FI-00290 Helsinki, Finland
| | - Jan-Erik Raitanen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
| | - Jukka Moilanen
- Ophthalmology, University of Helsinki and Helsinki University Hospital, Haartmaninkatu 8, FI-00290 Helsinki, Finland
| | - Riku O Paananen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland.,Ophthalmology, University of Helsinki and Helsinki University Hospital, Haartmaninkatu 8, FI-00290 Helsinki, Finland
| | - Filip S Ekholm
- Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland
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13
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Yeh TN, Lin MC. Meibomian Gland Contrast Sensitivity and Specificity in the Diagnosis of Lipid-deficient Dry Eye: A Pilot Study. Optom Vis Sci 2021; 98:121-126. [PMID: 33534375 PMCID: PMC7897301 DOI: 10.1097/opx.0000000000001636] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE Lipid deficiency due to meibomian gland (MG) dysfunction is believed to account for the vast majority of patients with dry eye compared with aqueous deficiency. Clinicians commonly evaluate MG length to determine a disease, but our research with isotretinoin users suggests that MG contrast is also an important characteristic to consider. PURPOSE This study aimed to determine the sensitivity and specificity of MG contrast for the diagnosis of lipid-deficient dry eye (LDDE). METHODS This case-control study used demographic data, Standard Patient Evaluation of Eye Dryness (SPEED) scores, average tear lipid layer thickness (TLLT), fluorescein tear breakup time (FTBUT), upper eyelid meibography images, and meibum quality and quantity scores for individuals with LDDE (SPEED score ≥10 and TLLT ≤35 interferometric color units) and normal individuals (SPEED ≤2 and TLLT ≥80 interferometric color units). RESULTS Thirty-one eyes of 22 controls (mean ± SD age, 22.7 ± 5.5 years) and 13 eyes of 12 cases (mean ± SD age, 43.9 ± 17.2 years) were included. Normalized MG contrast was significantly correlated with FTBUT (r = 0.35, P = .02), percent MG atrophy (r = -0.50, P < .001), and SPEED scores (r = -0.49, P < .001). The receiver operating characteristic curve for LDDE diagnosis classifiers MG contrast, MG atrophy, and meibum quantity score had areas under the curve of 0.83, 0.64, and 0.73, respectively. Meibomian gland contrast cutoff at 28.3 intensity units yielded optimal correct classification of subjects (84.1%; sensitivity, 0.69; specificity, 0.90). Cases had shorter FTBUT (P < .001), worse meibum quality (P = .02) and quantity (P = .02) scores, and lower MG contrast (P < .001) compared with controls. Subjects with low MG contrast (≤28.3) had 14.9 higher odds of having LDDE (95% confidence interval, 2.84 to 78.4) compared with subjects with high MG contrast (>28.3). CONCLUSIONS Meibomian gland contrast correlates well with clinical parameters and symptoms, shows good sensitivity and excellent specificity for diagnosing LDDE, and can be a useful diagnostic parameter for monitoring MG changes due to age, disease, or intervention.
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Affiliation(s)
- Thao N Yeh
- Clinical Research Center, and Vision Science Group, School of Optometry, University of California, Berkeley, Berkeley, California
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14
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Svitova TF, Lin MC. Evaporation retardation by model tear-lipid films: The roles of film aging, compositions and interfacial rheological properties. Colloids Surf B Biointerfaces 2021; 197:111392. [DOI: 10.1016/j.colsurfb.2020.111392] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 09/22/2020] [Accepted: 09/28/2020] [Indexed: 01/07/2023]
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15
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Shah AM, Galor A. Impact of Ocular Surface Temperature on Tear Characteristics: Current Insights. CLINICAL OPTOMETRY 2021; 13:51-62. [PMID: 33623465 PMCID: PMC7894805 DOI: 10.2147/opto.s281601] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/20/2021] [Indexed: 05/12/2023]
Abstract
Infrared (IR) thermographic assessment of ocular surface temperature (OST) is gaining interest as an adjuvant method to evaluate the ocular surface. It is a quick, non-invasive test that causes minimal, if any, discomfort to patients. The purpose of this article was to summarize research on how OST relates to tear film parameters and dry eye disease (DED). PubMed, Google Scholar, and Scopus searches for specific terms were carried out and eligible articles reviewed. OST of the central cornea is ~34-35°C when measured as a single time-point (typically right after a blink). Dynamically, OST values decrease over time at a rate of ~ -0.01 °C/s in healthy eyes. Single time-point OST values are impacted by temperature, with positive correlations noted with both ambient (1°C↓ results in ~0.16°C↓ in OST) and body (1°C↑ results in ~0.98°C↑ in OST) temperature. Single time-point OST values are also impacted by tear parameters, with negative correlations noted with tear break-up time (TBUT; r=-0.61) and positive correlations with lipid layer thickness (~r=0.50). Dynamically, the rate of OST cooling over the interblink period correlates with various tear parameters including Schirmer's test scores (r=-0.39), tear meniscus height (r=-0.52) and the rate of tear film break-up (r=-0.74). These data imply that OST decreases more rapidly in individuals with greater tear production, larger tear volumes, and shorter tear break-up times (faster rates of tear film break-up). There are discrepancies in relationships between OST and DED across studies, which is not surprising given that DED encompasses a number of different phenotypic presentations. However, most studies found that OST decreases at a more rapid rate in DED vs. control groups. As such, cooling rate may have utility as a screening tool in DED in combination with established point-of-care tests.
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Affiliation(s)
- Ankit M Shah
- Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
| | - Anat Galor
- Bascom Palmer Eye Institute, University of Miami, Miami, FL, USA
- Surgical Services, Miami Veterans Affairs (VA) Medical Center, Miami, FL, USA
- Correspondence: Anat Galor Bascom Palmer Eye Institute, 900 NW 17th St, Miami, FL, 33136, USA Email
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16
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Luke RA, Braun RJ, Driscoll TA, Begley CG, Awisi-Gyau D. Parameter Estimation for Evaporation-Driven Tear Film Thinning. Bull Math Biol 2020; 82:71. [DOI: 10.1007/s11538-020-00745-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 05/05/2020] [Indexed: 12/13/2022]
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17
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Affiliation(s)
- Young Hyun Kim
- Vision Science Graduate Group, University of California, Berkeley, CA, USA
- Clinical Research Center, School of Optometry, University of California, Berkeley, CA, USA
- Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA, USA
| | - Bo Tan
- Clinical Research Center, School of Optometry, University of California, Berkeley, CA, USA
| | - Meng C. Lin
- Vision Science Graduate Group, University of California, Berkeley, CA, USA
- Clinical Research Center, School of Optometry, University of California, Berkeley, CA, USA
| | - Clayton J. Radke
- Vision Science Graduate Group, University of California, Berkeley, CA, USA
- Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA, USA
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