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Magone MT, Schuck P. Evaluating Moisture Migration in Schirmer Test Strips: Exploring Brand-Specific Variations and Introducing Calibration and Conversion Methods. Cornea 2024; 43:635-640. [PMID: 38015937 PMCID: PMC10980172 DOI: 10.1097/ico.0000000000003430] [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: 07/15/2023] [Revised: 10/01/2023] [Accepted: 10/16/2023] [Indexed: 11/30/2023]
Abstract
PURPOSE Schirmer test results are widely used for ocular surface disease assessment, but Schirmer strips are not standardized. We compare the characteristics and tear volume with millimeter moisture migration in different brands of Schirmer strips and introduce methods for volume-based, brand-independent calibration. METHODS Physical parameters of Haag-Streit, EagleVision, TearFlo, Contacare, and MIPL/A6 Schirmer strip brands were compared. Schirmer strip millimeter moisture migration distances were assessed 5 minutes after application of incremental microliter volumes of human tears. Linear regression analysis of data points from each Schirmer strip brand was performed, and the root-mean-square deviation of data points to the best-fit linear regression was calculated. Calibration correction was performed by converting migration distance to the corresponding tear volume. A reference table and calibration method formulas were created. RESULTS Schirmer strips differed in design, shape, and manufacturing precision. Strip width, weight, and length were different between the 5 brands ( P < 0.05). A wide range of Schirmer strip moisture migration values for identical tear volumes was observed among brands. Statistical measurement resulted in a root-mean-square deviation of 2.9 mm for all data points from all brands. Millimeter to volume and weight to volume-based calibration correction methods resulted in a 2.2- and 3.1-fold measurement error reduction, respectively. CONCLUSIONS Our findings highlight the lack of standardization among different brands of Schirmer strips, raising concerns about potential sources of unintentional measurement errors. We propose volume-based Schirmer strip calibration methods and conversion of millimeter to microliter results to achieve brand-independent results and improve Schirmer test accuracy.
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Affiliation(s)
- M. Teresa Magone
- Consult Services Section, National Eye Institute, National Institutes of Health, Bethesda, MD; and
| | - Peter Schuck
- Laboratory of Dynamics of Macromolecular Assembly, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD
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2
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Ponzini E. Tear biomarkers. Adv Clin Chem 2024; 120:69-115. [PMID: 38762243 DOI: 10.1016/bs.acc.2024.03.002] [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] [Indexed: 05/20/2024]
Abstract
An extensive exploration of lacrimal fluid molecular biomarkers in understanding and diagnosing a spectrum of ocular and systemic diseases is presented. The chapter provides an overview of lacrimal fluid composition, elucidating the roles of proteins, lipids, metabolites, and nucleic acids within the tear film. Pooled versus single-tear analysis is discussed to underline the benefits and challenges associated with both approaches, offering insights into optimal strategies for tear sample analysis. Subsequently, an in-depth analysis of tear collection methods is presented, with a focus on Schirmer's test strips and microcapillary tubes methods. Alternative tear collection techniques are also explored, shedding light on their applicability and advantages. Variability factors, including age, sex, and diurnal fluctuations, are examined in the context of their impact on tear biomarker analysis. The main body of the chapter is dedicated to discussing specific biomarkers associated with ocular discomfort and a wide array of ocular diseases. From dry eye disease and thyroid-associated ophthalmopathy to keratoconus, age-related macular degeneration, diabetic retinopathy, and glaucoma, the intricate relationship between molecular biomarkers and these conditions is thoroughly dissected. Expanding beyond ocular pathologies, the chapter explores the applicability of tear biomarkers in diagnosing systemic diseases such as multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer's disease, Parkinson's disease, and cancer. This broader perspective underscores the potential of lacrimal fluid analysis in offering non-invasive diagnostic tools for conditions with far-reaching implications.
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Affiliation(s)
- Erika Ponzini
- Department of Materials Science, University of Milano Bicocca, Milan, Italy; COMiB Research Center, University of Milano Bicocca, Milan, Italy.
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3
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Wolffsohn JS. 2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management. Optom Vis Sci 2024; 101:12-24. [PMID: 38350054 DOI: 10.1097/opx.0000000000002102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024] Open
Abstract
ABSTRACT Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.
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4
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Gijs M, Arumugam S, van de Sande N, Webers CAB, Sethu S, Ghosh A, Shetty R, Vehof J, Nuijts RMMA. Pre-analytical sample handling effects on tear fluid protein levels. Sci Rep 2023; 13:1317. [PMID: 36693949 PMCID: PMC9873914 DOI: 10.1038/s41598-023-28363-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 01/16/2023] [Indexed: 01/25/2023] Open
Abstract
Tear fluid is emerging as a source of non-invasive biomarkers, both for ocular and systemic conditions. Accurate quantification of tear proteins can be improved by standardizing methods to collect and process tear fluid. The aim of this study was to determine sample handling factors that may influence the tear protein biomarker profile. Tear fluid was collected using Schirmer's strips. Tear proteins were extracted by elution through centrifugation. Total protein content was determined using the bicinchoninic acid assay. Key concepts that apply to the entire sample processing cycle are tear sampling, tear storage, protein extraction and data normalization. Differences in wetting or migration length were observed between Schirmer's strips from different manufacturers, and between protein-free and protein-rich solutions. One unit of migration length (mm) did not correspond to one unit of volume (µL). A positive correlation (r = 0.6671, p < 0.0001) was observed between migration length and total tear protein content. The most beneficial storage conditions were strips that were not stored (+ 21.8%), or underwent 'wet' storage (+ 11.1%). Protein recovery was the highest in 400 µL extraction buffer and independent of protein molecular weight. This study helps to explain inter- and intra-variability that is often seen with tear biomarker research. This information is critical to ensure accuracy of test results, as tear biomarkers will be used for patient management and in clinical trials in the near future. This study also highlights the need for standardization of Schirmer's strip manufacturing, tear fluid processing and analyte concentration normalization.
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Affiliation(s)
- Marlies Gijs
- University Eye Clinic Maastricht, School for Mental Health and Neuroscience (MHeNs), Maastricht University Medical Center (MUMC+), P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.
| | - Sinthuja Arumugam
- University Eye Clinic Maastricht, School for Mental Health and Neuroscience (MHeNs), Maastricht University Medical Center (MUMC+), P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands
| | - Nienke van de Sande
- University Eye Clinic Maastricht, School for Mental Health and Neuroscience (MHeNs), Maastricht University Medical Center (MUMC+), P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands
| | - Carroll A B Webers
- University Eye Clinic Maastricht, School for Mental Health and Neuroscience (MHeNs), Maastricht University Medical Center (MUMC+), P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands
| | - Swaminathan Sethu
- GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, India
| | - Arkasubhra Ghosh
- GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, India
| | - Rohit Shetty
- University Eye Clinic Maastricht, School for Mental Health and Neuroscience (MHeNs), Maastricht University Medical Center (MUMC+), P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.,GROW Research Laboratory, Narayana Nethralaya Foundation, Bangalore, India.,Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Jelle Vehof
- Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Dutch Dry Eye Clinic, Velp, The Netherlands.,Department of Ophthalmology, Vestfold Hospital Trust, Tønsberg, Norway
| | - Rudy M M A Nuijts
- University Eye Clinic Maastricht, School for Mental Health and Neuroscience (MHeNs), Maastricht University Medical Center (MUMC+), P. Debyelaan 25, 6229 HX, Maastricht, The Netherlands.,Department of Ophthalmology, Zuyderland Medical Center, Heerlen, The Netherlands
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5
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An Extensive Study of Phenol Red Thread as a Novel Non-Invasive Tear Sampling Technique for Proteomics Studies: Comparison with Two Commonly Used Methods. Int J Mol Sci 2022; 23:ijms23158647. [PMID: 35955782 PMCID: PMC9369290 DOI: 10.3390/ijms23158647] [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: 06/27/2022] [Revised: 07/22/2022] [Accepted: 07/30/2022] [Indexed: 02/04/2023] Open
Abstract
Tear samples are considered in recent publications as easily, noninvasively collectible information sources for precision medicine. Their complex composition may aid the identification of biomarkers and the monitoring of the effectiveness of treatments for the eye and systemic diseases. Sample collection and processing are key steps in any analytical method, especially if subtle personal differences need to be detected. In this work, we evaluate the usability of a novel sample collection technique for human tear samples using phenol red threads (cotton thread treated with the pH indicator phenol red), which are efficiently used to measure tear volume in clinical diagnosis. The low invasiveness and low discomfort to the patients have already been demonstrated, but their applicability for proteomic sample collection has not yet been compared to other methods. We have shown, using various statistical approaches, the qualitative and quantitative differences in proteomic samples collected with this novel and two traditional methods using either glass capillaries or Schirmer’s paper strips. In all parameters studied, the phenol red threads proved to be equally or even more suitable than traditional methods. Based on detectability using different sampling methods, we have classified proteins in tear samples.
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Symptoms of Dry Eye Disease in Hospitalized Patients with Coronavirus Disease 2019 (COVID-19). J Ophthalmol 2021; 2021:2678706. [PMID: 34912574 PMCID: PMC8668290 DOI: 10.1155/2021/2678706] [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: 09/21/2021] [Revised: 10/21/2021] [Accepted: 10/29/2021] [Indexed: 11/25/2022] Open
Abstract
Background We aimed to investigate the symptoms of the dry eye disease (DED) of hospitalized patients with coronavirus disease 2019 (COVID-19). Methods This cross-sectional, observational study analysis included 91 hospitalized patients with confirmed COVID-19 in Wuhan, China. The Ocular Surface Disease Index (OSDI) and the five-item Dry Eye Questionnaire (DEQ-5) were used to assess the severity of DED symptoms in the patients, and the analysis of variance was used to determine the factors associated with DED. Results A total of 42 patients consented to complete the investigation (response rate 46.15%). There were 26 (61.90%) patients who were diagnosed with DED symptoms by OSDI, and there were 28 (66.67%) patients with DED symptoms who were diagnosed by DEQ-5 score. For the biochemical tests, the patients with DED symptoms had lower aspartate aminotransferase (AST) levels compared to those with no DED symptoms (20.86 vs. 42.14, p=0.04). Further analysis showed that a previous history of cardiac or stroke disease (p=0.02) and typical symptoms of muscle soreness (p=0.03) were significantly different among the four DED symptoms groups on the basis of OSDI scores. The contributing factors of OSDI were mainly focused on visual function and environmental triggers. Conclusion The incidence of DED symptoms is higher in hospitalized patients with COVID-19. The serum AST levels, history of cardiac or stroke disease, and the typical symptoms of muscle soreness may be the main impact factors on DED symptoms. We also need to pay more attention to the visual function and environmental triggers of hospitalized patients with COVID-19.
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Nättinen J, Aapola U, Nukareddy P, Uusitalo H. Looking deeper into ocular surface health: an introduction to clinical tear proteomics analysis. Acta Ophthalmol 2021; 100:486-498. [PMID: 34750985 DOI: 10.1111/aos.15059] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 10/13/2021] [Accepted: 10/25/2021] [Indexed: 12/13/2022]
Abstract
Ocular surface diseases are becoming more prevalent worldwide. Reasons for this include the ongoing population ageing and increasing use of digital displays, although ophthalmologists have a wide selection of tools, which can be implemented in the evaluation of the ocular surface health, methods, which enable the in-depth study of biological functions are gaining more interest. These new approaches are needed, since the individual responses to ocular surface diseases and treatments can vary from person to person, and the correlations between clinical signs and symptoms are often low. Modern mass spectrometry (MS) methods can produce information on hundreds of tear proteins, which in turn can provide valuable information on the biological effects occurring on the ocular surface. In this review article, we will provide an overview of the different aspects, which are part of a successful tear proteomics study design and equip readers with a better understanding of the methods most suited for their MS-based tear proteomics study in the field of ophthalmology and ocular surface.
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Affiliation(s)
- Janika Nättinen
- SILK Department of Ophthalmology Faculty of Medicine and Health Technology Tampere University Tampere Finland
| | - Ulla Aapola
- SILK Department of Ophthalmology Faculty of Medicine and Health Technology Tampere University Tampere Finland
| | - Praveena Nukareddy
- SILK Department of Ophthalmology Faculty of Medicine and Health Technology Tampere University Tampere Finland
| | - Hannu Uusitalo
- SILK Department of Ophthalmology Faculty of Medicine and Health Technology Tampere University Tampere Finland
- Tays Eye Centre Tampere University Hospital Tampere Finland
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Adigal SS, Rizvi A, Rayaroth NV, John RV, Barik A, Bhandari S, George SD, Lukose J, Kartha VB, Chidangil S. Human tear fluid analysis for clinical applications: progress and prospects. Expert Rev Mol Diagn 2021; 21:767-787. [PMID: 34115952 DOI: 10.1080/14737159.2021.1941879] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Introduction: Human blood and saliva are increasingly under investigation for the detection of biomarkers for early diagnosis of non-communicable (e.g.cancers) and communicable diseases like COVID-19. Exploring the potential application of human tears, an easily accessible body fluid, for the diagnosis of various diseases is the need of the hour.Areas covered: This review deals with a comprehensive account of applications of tear analysis using different techniques, their comparison and overall progress achieved till now. The techniques used for tear fluid analysis are HPLC/UPLC/SDS-PAGE, CE, etc., together with ELISA, Mass Spectrometry, etc. But, with advances in instrumentation and data processing methods, it has become easy to couple the various separation methods with highly sensitive optical techniques for the analysis of body fluids.Expert opinion: Tear analysis can provide valuable information about the health condition of the eyes since it contains several molecular constituents, and their relative concentrations may alter under abnormal conditions. Tear analysis has the advantage that it is totally non-invasive. This study recommends tear fluid as a reliable clinical sample to be probed by highly sensitive optical techniques to diagnose different health conditions, with special emphasis on eye diseases.
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Affiliation(s)
- Sphurti S Adigal
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Alisha Rizvi
- Department of Ophthalmology, Kasthurba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Nidheesh V Rayaroth
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Reena V John
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Ajayakumar Barik
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Sulatha Bhandari
- Department of Ophthalmology, Kasthurba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Sajan D George
- Centre for Applied Nanotechnology, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Jijo Lukose
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Vasudevan B Kartha
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Santhosh Chidangil
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, India
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Shukla AK, Pinard CL, Flynn BL, Bauman CA. Effects of orally administered gabapentin, tramadol, and meloxicam on ocular variables in healthy dogs. Am J Vet Res 2020; 81:973-984. [PMID: 33251843 DOI: 10.2460/ajvr.81.12.973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the effects of gabapentin, tramadol, and meloxicam on tear production, intraocular pressure (IOP), pupillary diameter, tear break-up time, and corneal touch threshold in healthy dogs when given orally for 3 days. ANIMALS 9 healthy research Beagles. PROCEDURES A randomized, blinded, case-crossover study with a 6-sequence, 3-treatment, and 3-period design was performed. A 7-day acclimation period was followed by 3 treatment phases, each with a 3-day treatment period followed by a 7-day washout period for 3 different drugs. Block randomization was used to group dogs for treatments with drug A (gabapentin), B (tramadol), or C (meloxicam). Measurements of tear production, IOP, pupillary diameter, tear break-up time, and corneal touch threshold were performed on a schedule. A generalized mixed-effects linear regression model was created for each ocular variable, accounting for repeated measures within individuals. RESULTS Intraocular pressure was the only variable to have differed substantially between the first 5 and last 2 days of the acclimation period. When treatment phase, day, time of day, dog identification, baseline value, and eye were accounted for, the mean IOP was lower for dogs during treatment phases with gabapentin or tramadol, compared with meloxicam, but this difference was not considered clinically meaningful. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a minimum 5-day acclimation period is necessary for IOP measurements to return to baseline in dogs. The statistically identified effect of gabapentin and tramadol on IOP in dogs of the present study warrants further investigation. It is possible that at higher dosages, or in dogs with glaucoma, this effect may become clinically significant.
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10
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Huang C, Zhang X, Li Y, Yang X. Hyaluronic acid and graphene oxide loaded silicon contact lens for corneal epithelial healing. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2020; 32:372-384. [PMID: 33058750 DOI: 10.1080/09205063.2020.1836926] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Hyaluronic acid (HA) eye drop solution is widely used to treat and manage various corneal diseases like keratoconus (after corneal cross-linking) and dry eye syndrome. However, ocular dosage forms like eye drop solution affect the routine life style of patients due to frequent dosing schedule. In this study, HA and reduced graphene oxide (rGO) was directly loaded in the silicon contact lenses (HA-GO-DL) and compared with the conventional soaking method (HA-GO-SM). The contact lenses at lower level of rGO showed permissible swelling and transmittance properties. The water retention property of HA-GO-DL contact lenses was confirmed by water evaporation studies. The flux data of HA-GO-SM contact lenses showed high burst release with 24 h release duration. While, HA-GO-DL lenses confirmed low burst with sustained release up to 96 h. In ocular irritation study, the HA-GO-DL-2 lenses was found to be safe. The HA-GO-DL-2 batch showed high HA-tear fluid concentration (rabbit model) and improvement in the rabbit tear fluid volume (Schirmer strip studies) in comparison to the soaking method (HA-GO-SM-2) and eye drop solution. The study successfully demonstrate the potential of HA-GO loaded contact lenses to improve tear fluid volume to manage various ocular diseases like dry eye syndrome.
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Affiliation(s)
- Chao Huang
- Department of Ophthalmology, The Second People's Hospital of Jinan, Jinan, Shandong Province, China
| | - Xin Zhang
- Department of Ophthalmology, The Second People's Hospital of Jinan, Jinan, Shandong Province, China
| | - Yanchun Li
- Department of Ophthalmology, The Second Affiliated Hospital of Shandong First Medical University, Taian City, Shandong Province, China
| | - Xiaolan Yang
- Department of Fundus Disease, The Second People's Hospital of Jinan, Jinan, Shandong Province, China
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11
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Lewin AC, Liu CC, Yoon A, Mironovich M, Miessler B, Carter RT. Schirmer strip wetting length varies by commercial manufacturer. Vet Ophthalmol 2020; 23:1031-1035. [PMID: 33058382 DOI: 10.1111/vop.12835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 09/18/2020] [Accepted: 09/27/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine whether wetting length of Schirmer tear test (STT) strips varies by commercial manufacturer of test. ANIMALS STUDIED Ten normal female beagle cross-breed dogs. PROCEDURES Schirmer tear test strips from four commercial manufacturers were used to assess wetting lengths in-vitro when exposed to a set volume of water over 1 minute. Digital photography was used to assess the total surface area of Schirmer strips from each manufacturer. Schirmer tear test type 1 was performed on normal dogs over 1 minute with STT strips from the same four commercial manufacturers in a randomized crossover design. ANOVA was used to detect differences between strips from different manufacturers. RESULTS Significant differences in wetting length were found between STT strips from different manufacturers in-vitro (P < .0001) and in-vivo (P < .0001). STT wetting lengths for the in-vitro experiments (mean ± SD) were 21.2 ± 0.8 mm (Amcon Laboratories), 27.8 ± 2.7 mm (Merck Animal Health), 30.0 ± 1.7 mm (HUB pharmaceuticals), and 31.5 ± 2.3 mm (Gulden Ophthalmics). STT wetting lengths for the experiments in live dogs (mean ± SD) were 17.5 ± 3.4 mm (Amcon Laboratories), 24.8 ± 3.9 mm (Merck Animal Health), 26.5 ± 3.7 mm (HUB pharmaceuticals), and 24.0 ± 3.9 mm (Gulden Ophthalmics). The surface area of STT strips were found to vary between different manufacturers. CONCLUSIONS Schirmer tear test type 1 results in dogs are affected by choice of STT strip commercial manufacturer. It is proposed that guidelines are created for the standardization of future STT strip production.
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Affiliation(s)
- Andrew C Lewin
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Chin-Chi Liu
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Angela Yoon
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Melanie Mironovich
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Bruna Miessler
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Renee T Carter
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
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12
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Barmada A, Shippy SA. Quantifying Sample Collection and Processing Impacts on Fiber-Based Tear Fluid Chemical Analysis. Transl Vis Sci Technol 2020; 9:23. [PMID: 33024616 PMCID: PMC7521181 DOI: 10.1167/tvst.9.10.23] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 08/10/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose Noninvasive analyses of tear fluid from humans and animal models in clinical and research settings most commonly use absorbent material for collection and processing. Still, the impact of these analytical techniques on tear chemical analyses remains largely unknown. The purpose of this study was to quantify the impacts of phenol red thread fiber-based tear sample collection and processing on the primary amine content. Methods Human tears were collected by placing the folded end of phenol red thread on the palpebral conjunctiva of the right eye for 20 seconds. The wetted thread was then processed using elution or extraction, and capillary electrophoresis with light-emitting diode-induced fluorescence detection was used for analysis and quantitation. Results Distinct processing methods impacted tear analysis differently. Primary amines adsorbed onto the thread partitioned in a chromatographic manner and thus any single portion of the wetted thread might not be representative of the whole sample. Quantitative assessment of five small molecule standards after on-thread processing showed significant overestimation of the actual concentration, with increased accuracy for larger volume samples. Yet collection of larger tear volumes introduced error in volume determination owing to evaporation and reduced small molecule separation resolution. Conclusions These results indicated that absorption-based tear fluid collection and processing significantly alter chemical content analysis, suggesting that the impacts of methods used should be regularly evaluated to standardize results drawn from different studies. Translational Relevance This study identifies potential inconsistencies and inaccuracies in tear analyses that are widespread across the published literature and clinical care.
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Affiliation(s)
- Anis Barmada
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, United States
| | - Scott A Shippy
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, United States.,Laboratory of Integrative Neuroscience, University of Illinois at Chicago, Chicago, Illinois, United States
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13
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Justis BM, Coburn CE, Tyler EM, Showalter RS, Dissler BJ, Li M, McNamara NA, Laurie GW, McKown RL. Development of a Quantitative Immunoassay for Tear Lacritin Proteoforms. Transl Vis Sci Technol 2020; 9:13. [PMID: 32879769 PMCID: PMC7442861 DOI: 10.1167/tvst.9.9.13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 06/18/2020] [Indexed: 12/12/2022] Open
Abstract
Purpose Lacritin is a tear glycoprotein with pro-tearing and pro-ocular surface homeostasis activities that is selectively deficient in most dry eye tears. Proteoforms include an active monomer, inactive polymers, and a splice variant termed lacritin-c. Quantitation of the different proteoforms of tear lacritin may provide a diagnostic tool for ocular diseases. Here, we report the development of an immunoassay for the quantification of multiple lacritin proteoforms in human tear samples. Methods Basal tears collected on Schirmer test strips with anesthesia were eluted by diffusion and centrifugation under optimized conditions. Tear protein concentrations were determined, and 2.56 µg of each sample was separated by SDS-PAGE followed by western blot analysis. Blots were challenged with anti-Pep Lac N-term antibodies. Detection was with fluorescent secondary antibodies visualized by the LI-COR Odyssey CLx imaging system and quantified with standard curves of recombinant lacritin. Results The percent total lacritin (ng lacritin/100 ng total protein) ranged from 1.8% to 14.8%. Monomer, lacritin-c, and polymer proteoform percent total protein ranged from 1.1% to 6.3%, 0.3% to 5.4%, and 0.7% to 5.7%, respectively. Monomer lacritin was detected at concentrations of 6 to 176 µM, with lacritin-c and polymer proteoforms at 2 to 46 µM and 1 to 23 µM, respectively. Conclusions This assay greatly exceeds the power and sensitivity of our prior lacritin enzyme-linked immunosorbent assay that was not capable of distinguishing monomer from polymers and lacritin-c proteoforms. Translational Relevance A new method has been developed to quantitate multiple proteoforms of tear lacritin in preparation for analyses of samples from clinical trials.
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Affiliation(s)
- Brooke M Justis
- School of Integrated Sciences, James Madison University, Harrisonburg, VA USA
| | - Casey E Coburn
- School of Integrated Sciences, James Madison University, Harrisonburg, VA USA
| | - Ethan M Tyler
- School of Integrated Sciences, James Madison University, Harrisonburg, VA USA
| | - Ryan S Showalter
- School of Integrated Sciences, James Madison University, Harrisonburg, VA USA
| | - Brianna J Dissler
- School of Integrated Sciences, James Madison University, Harrisonburg, VA USA
| | - Melissa Li
- School of Optometry and Vision Science Program, University of California, Berkeley, Berkeley, CA, USA
| | - Nancy A McNamara
- School of Optometry and Vision Science Program, University of California, Berkeley, Berkeley, CA, USA.,Department of Anatomy, University of California, San Francisco, San Francisco, CA, USA
| | - Gordon W Laurie
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA.,Department of Ophthalmology, University of Virginia, Charlottesville, VA, USA.,Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, USA
| | - Robert L McKown
- School of Integrated Sciences, James Madison University, Harrisonburg, VA USA
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14
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Raposo AC, Lebrilla CB, Portela RW, Goonatilleke E, Neto FAD, Oriá AP. The proteomics of roadside hawk (Rupornis magnirostris), broad-snouted caiman (Caiman latirostris) and loggerhead sea turtle (Caretta caretta) tears. BMC Vet Res 2020; 16:276. [PMID: 32767984 PMCID: PMC7412644 DOI: 10.1186/s12917-020-02495-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 07/27/2020] [Indexed: 12/26/2022] Open
Abstract
Background Tears play an important role in ocular surface protection, and help wild animals maintain visual acuity in the face of air and water friction. The proteomics of tears has only been described for mammals. The knowledge of the proteomics of wild animal tears can aid not only in the setting of normal standards for ocular disease studies in these animals, but also to base the search for new molecules to be used in ophthalmology therapeutics. We therefore set out to describe the proteomic profile of roadside hawk (Rupornis magnirostris), broad-snouted caiman (Caiman latirostris) and loggerhead sea turtle (Caretta caretta) tears. Tears were collected from healthy animals, their spectral profiles were obtained with an LTQ Orbitrap XL mass spectrometer, and the dataset was analyzed against reference taxa. Results For roadside hawk, 446 proteins were identified, the most abundant being albumin, transferrin, globulin and actin. For broad-snouted caiman and loggerhead sea turtle, 1358 and 163 proteins were identified, respectively. Uncharacterized proteins and transferrin were highly abundant in both species. The roadside hawk tear components and their properties were similar to those described for humans, but with a higher albumin concentration. Broad-snouted caiman tears presented a wide diversity of ontological functions, with an abundant presence of enzymatic compounds. In loggerhead sea turtle tears, the predominance of proteins with ion-transport functions was consistent with possible osmolality-maintenance mechanisms. Conclusion These data enhance our understanding of birds and reptiles’ tears microcomposition and may be used to base the discovery of new molecules with high biotechnological potential.
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Affiliation(s)
- A C Raposo
- School of Veterinary Medicine, Federal University of Bahia, Salvador, 40110-060, Brazil
| | - C B Lebrilla
- Chemistry Department, Mass Spectrometry Facilities Campus, University of California, Davis, CA, 95616-8585, USA
| | - R W Portela
- Institute of Health Sciences, Federal University of Bahia, Salvador, 40110-100, Brazil
| | - E Goonatilleke
- Chemistry Department, Mass Spectrometry Facilities Campus, University of California, Davis, CA, 95616-8585, USA
| | - F A Dórea Neto
- School of Veterinary Medicine, Federal University of Bahia, Salvador, 40110-060, Brazil
| | - A P Oriá
- School of Veterinary Medicine, Federal University of Bahia, Salvador, 40110-060, Brazil.
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15
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Sebbag L, Mochel JP. An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface. Med Res Rev 2020; 40:2566-2604. [PMID: 32735080 DOI: 10.1002/med.21716] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/01/2020] [Accepted: 07/15/2020] [Indexed: 12/15/2022]
Abstract
Preclinical animal studies provide valuable opportunities to better understand human diseases and contribute to major advances in medicine. This review provides a comprehensive overview of ocular parameters in humans and selected animals, with a focus on the ocular surface, detailing species differences in ocular surface anatomy, physiology, tear film dynamics and tear film composition. We describe major pitfalls that tremendously limit the translational potential of traditional laboratory animals (i.e., rabbits, mice, and rats) in ophthalmic research, and highlight the benefits of integrating companion dogs with clinical analogues to human diseases into preclinical pharmacology studies. This One Health approach can help accelerate and improve the framework in which ophthalmic research is translated to the human clinic. Studies can be conducted in canine subjects with naturally occurring or noninvasively induced ocular surface disorders (e.g., dry eye disease, conjunctivitis), reviewed herein, and tear fluid can be easily retrieved from canine eyes for various bioanalytical purposes. In this review, we discuss common tear collection methods, including capillary tubes and Schirmer tear strips, and provide guidelines for tear sampling and extraction to improve the reliability of analyte quantification (drugs, proteins, others).
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Affiliation(s)
- Lionel Sebbag
- Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA.,Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Jonathan P Mochel
- Department of Biomedical Sciences, SMART Pharmacology, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
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16
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Sebbag L, Uhl LK, Schneider B, Hayes B, Olds J, Mochel JP. Investigation of Schirmer tear test-1 for measurement of tear production in cats in various environmental settings and with different test durations. J Am Vet Med Assoc 2020; 256:681-686. [PMID: 32125244 DOI: 10.2460/javma.256.6.681] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To assess reliability of the Schirmer tear test-1 (STT-1) for measurement of tear production in cats in various environments, investigate whether sympathetic stimulation impacts measurements, and determine whether meaningful conclusions regarding lacrimation in cats can be drawn from STT-1 measurements obtained with STT strip placement for < 1 minute. ANIMALS 176 cats examined in a private practice (n = 100), a feral cat clinic (56), or a veterinary teaching hospital (20). PROCEDURES The STT-1 was performed in both eyes of each cat. Measurements were recorded at 10- or 30-second intervals for 1 minute. Cats at the teaching hospital were tested once in a quiet examination room (unstimulated conditions) and once in the same room with loud prerecorded noises (stimulated conditions), with a 30-minute interval between tests and evaluation of cats' heart rates before and after STT-1. Data were analyzed with parametric statistical tools and a nonlinear mixed-effect model. RESULTS 30- and 60-second STT-1 measurements were significantly correlated (r = 0.94). The STT-1 measurements did not differ under nonstimulated versus stimulated conditions, despite significant changes in heart rates that indicated sympathetic stimulation. A hyperbolic model of STT-1 kinetics was validated, allowing for extrapolation of measurements obtained in < 60 seconds and generation of reference values (95% predictive intervals) for various test durations. Median (95% predictive interval) 30- and 60-second STT-1 measurements were 9.1 mm (4.8 to 15.6 mm) and 14.3 mm (8.2 to 22.3 mm), respectively. CONCLUSIONS AND CLINICAL RELEVANCE The STT-1 was a reliable diagnostic test in all settings; results were not affected by sympathetic stimulation, and a shorter duration of testing could be considered in selected cases.
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17
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Ballard Z, Bazargan S, Jung D, Sathianathan S, Clemens A, Shir D, Al-Hashimi S, Ozcan A. Contact lens-based lysozyme detection in tear using a mobile sensor. LAB ON A CHIP 2020; 20:1493-1502. [PMID: 32227027 PMCID: PMC7189769 DOI: 10.1039/c9lc01039d] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We report a method for sensing analytes in tear-fluid using commercial contact lenses (CLs) as sample collectors for subsequent analysis with a cost-effective and field-portable reader. In this study we quantify lysozyme, the most prevalent protein in tear fluid, non-specifically bound to CLs worn by human participants. Our mobile reader uses time-lapse imaging to capture an increasing fluorescent signal in a standard well-plate, the rate-of-change of which is used to indirectly infer lysozyme concentration through the use of a standard curve. We empirically determined the best-suited CL material for our sampling procedure and assay, and subsequently monitored the lysozyme levels of nine healthy human participants over a two-week period. Of these participants who were regular CL wearers (6 out of 9), we observed an increase in lysozyme levels from 6.89 ± 2.02 μg mL-1 to 10.72 ± 3.22 μg mL-1 (mean ± SD) when inducing an instance of digital eye-strain by asking them to play a game on their mobile-phones during the CL wear-duration. We also observed a lower mean lysozyme concentration (2.43 ± 1.66 μg mL-1) in a patient cohort with dry eye disease (DED) as compared to the average monitoring level of healthy (no DED) human participants (6.89 ± 2.02 μg mL-1). Taken together, this study demonstrates tear-fluid analysis with simple and non-invasive sampling steps along with a rapid, easy-to-use, and cost-effective measurement system, ultimately indicating physiological differences in human participants. We believe this method could be used in future tear-fluid studies, even supporting multiplexed detection of a panel of tear biomarkers toward improved diagnostics and prognostics as well as personalized mobile-health applications.
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Affiliation(s)
- Zachary Ballard
- Department of Electrical and Computer Engineering, University of California, Los Angeles, USA.
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18
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Miyake H, Mori N, Mano H, Imanaka T, Nakamura M. Development of a highly sensitive and reliable enzyme-linked immunosorbent assay for MUC5AC in human tears extracted from Schirmer strips. Clin Ophthalmol 2018; 12:1571-1580. [PMID: 30214141 PMCID: PMC6120569 DOI: 10.2147/opth.s170552] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purpose Reliable measurement of MUC5AC in human tears is essential for elucidation of the pathophysiological role of MUC5AC in dry eye disease. The purpose of this study was to develop a sensitive and reliable method for measurement of MUC5AC in human tear samples extracted from Schirmer strips by modifying a commercially available ELISA. Methods MUC5AC was extracted from Schirmer strips containing human tears by PBS with various concentrations of polysorbate 20. The extracts were treated with neuraminidase A to cleave the sialic acids in MUC5AC. An ELISA plate was blocked to prevent nonspecific binding. The rate of extraction of MUC5AC from Schirmer strips, linearity of dilution, limit of quantification, calibration range, and intra-assay and inter-assay reproducibility were examined. Results MUC5AC was extracted using polysorbate 20 in a concentration-dependent manner. Extraction was more efficient at 37°C than at 25°C. The signal-to-noise ratio of the assay was dramatically increased by treatment with neuraminidase A. Treatment with a blocking reagent before incubation produced good linearity of dilution. The inter-assay and intra-assay coefficients of variation were ≤16.6%. The relative error was within 13%. Conclusion We developed an efficient method for extraction of MUC5AC from Schirmer strips and a highly sensitive, reliable assay for MUC5AC in human tear samples using a commercially available ELISA kit. This method will aid in our understanding of the pathophysiology of dry eye, assessment of the effects of treatment in daily practice, and selection of appropriate therapeutic agents for patients.
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Affiliation(s)
- Hideki Miyake
- Research and Development Division, Santen Pharmaceutical Co., Ltd., Osaka, Japan,
| | - Naoto Mori
- Research and Development Division, Santen Pharmaceutical Co., Ltd., Osaka, Japan,
| | - Hidetoshi Mano
- Research and Development Division, Santen Pharmaceutical Co., Ltd., Osaka, Japan,
| | - Takahiro Imanaka
- Research and Development Division, Santen Pharmaceutical Co., Ltd., Osaka, Japan,
| | - Masatsugu Nakamura
- Research and Development Division, Santen Pharmaceutical Co., Ltd., Osaka, Japan,
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