Investigation of inter- and intra-day variability of tear fluid regarding flow rate, protein concentration as well as protein composition

  • \(\bf Purpose:\) The purpose of this study was to present the determination of inter- and intra-day variations in tear flow rate, and tear fluid protein concentration, as well as protein composition regarding their impact for future biomarker studies. \(\bf Methods:\) Tear fluid was collected noninvasively from 18 healthy subjects by performing Schirmer tests at 4 different time points repetitive in a period of 2 days. The tear flow rate on the Schirmer test strips was measured. Proteins were extracted from strips and quantified using amino acid analysis. Protein composition was analyzed by the strips data-independent (DIA) based mass spectrometry. To exclude any impairments to health, volunteers underwent a detailed neurological as well as an ophthalmological examination. \(\bf Results:\) Whether tear fluid was collected from oculus sinister or oculus dexter did not affect the tear flow rate (\(\it P\) \(\thickapprox\) 0.63) or protein concentration (\(\it P\) \(\thickapprox\) 0.97) of individual subjects. Moreover, protein concentration was independent from the tear volume, so that a change in volume may only influence the total protein amount. When the examination days were compared, investigation of tear flow rate (\(\it P\) \(\thickapprox\) 0.001) and protein concentration (\(\it P\) \(\thickapprox\) 0.0003) indicated significant differences. Further, mass spectrometric analysis of tear fluid revealed 11 differentially regulated proteins when comparing both examination days. \(\bf Conclusions:\) Our findings provide evidence of inter-day variation in tear flow rate, tear proteome concentration, and composition in healthy subjects, suggesting that inter-day variation needs to be taken into consideration in biomarker research of tear fluid. Identified proteins were assigned to functions in the immune response, oxidative and reducing processes, as well as mannose metabolism.

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Author:Annika GuntermannORCiDGND, Oluwaseun FatobaGND, Marc KronenbergGND, Sabrina ReinehrORCiDGND, Pia GrotegutGND, Marc SchargusORCiDGND, Teresa TsaiGND, Svetlana IvanovaGND, Bettina SerschnitzkiGND, Nina Claudia KumowskiGND, Christoph MaierORCiDGND, Katrin Marcus-AlicORCiDGND, Burkhard DickORCiDGND, Stephanie Christine JoachimORCiDGND, Caroline MayORCiDGND
Parent Title (English):Investigative ophthalmology & visual science
Publisher:Association for Research in Vision and Ophthalmology
Place of publication:Rockville, Maryland
Document Type:Article
Date of Publication (online):2024/03/21
Date of first Publication:2023/10/10
Publishing Institution:Ruhr-Universität Bochum, Universitätsbibliothek
Tag:Open Access Fonds
Schirmer test; mass spectrometry; protein concentration; tear film; tear flow rate; tear volume
Issue:13, Artikel 13
First Page:13-1
Last Page:13-10
Article Processing Charge funded by the Deutsche Forschungsgemeinschaft (DFG) and the Open Access Publication Fund of Ruhr-Universität Bochum.
Institutes/Facilities:Medizinisches Proteom-Center
Dewey Decimal Classification:Technik, Medizin, angewandte Wissenschaften / Medizin, Gesundheit
open_access (DINI-Set):open_access
faculties:Medizinische Fakultät
Licence (English):License LogoCreative Commons - CC BY-NC-ND 4.0 - Attribution-NonCommercial-NoDerivatives 4.0 International