Diurnal variation on tear stability and correlation with tear cytokine concentration

Cristina Arroyo del Arroyo*, Mungunshur Byambajav, Itziar Fernández, Eilidh Martin, María Jesús González-García*, Alberto López-Miguel, Laura Valencia-Nieto, Suzanne Hagan, Amalia Enríquez-de-Salamanca

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
129 Downloads (Pure)

Abstract

Purpose: To investigate the effect of time of day on tear evaporation rate (TER) and tear break-up time, and its possible relationship with the concentration of inflammatory tear molecules (cytokines) in healthy subjects.

Methods: Participants with healthy ocular surfaces attended 3 visits, including the screening visit (V0), the 2nd visit (V1) and the 3rd visit (V2). There were 7-day intervals between visits. Participants with Dry Eye Disease (DED) were excluded by using appropriate clinical tests during V0. Clinical evaluation (TER and Non-Invasive Tear Break-Up Time (NITBUT)) and tear collection were performed during V1 and V2, between 9 and 10AM and 3-4PM. The relative humidity and temperature of the examination room were also measured. The tear fluid concentrations of 15 cytokines were measured by multiplex bead analysis.

Results: Seven men and 10 women (mean age ± S.D; 25.1 ± 6.63 years old) participated in the study. There were no differences in neither the TER and NITBUT outcomes, nor humidity and temperature among times or visits. Eleven out of the 15 cytokines measured were detectable in tear fluids in > 50% of the participants. In the tear levels, no significant (p > 0.05) inter- and/or intra-day differences were detected for EGF, fractalkine, IL-1RA, IL-1β and IP-10. However, significant inter-day differences were found in the tear levels of IL-10 (p = 0.027), IFN-γ (p = 0.035) and TNF-α(p = 0.04) and intra-day differences in the tear levels of IL-8/CXCL8 (p = 0.034) and MCP-1 (p = 0.002). A significant correlation between TER and IL1-β, IL-2, and Fractalkine (p = 0.03, p = 0.03 and p = 0.046, respectively) was found at V1.

Conclusions: NITBUT and TER values had no significant variability over the course of a day (AM versus PM), or on different days in healthy participants when humidity and temperature were constant. However, some tear molecule levels did show inter- and intra-day variability, having an inconsistent and moderate correlation with TER diurnal variation.

Original languageEnglish
Article number101705
Number of pages8
JournalContact Lens and Anterior Eye
Volume45
Issue number6
Early online date9 Nov 2022
DOIs
Publication statusPublished - Dec 2022

Keywords

  • Tear evaporation rate
  • Tear stability
  • Cytokines
  • Intra-day variation
  • Inter-day variation

ASJC Scopus subject areas

  • Ophthalmology
  • Optometry

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