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Cited by 32Ocular Surface and Contact LensSalivary Gland Disorders and FunctionsOcular Disorders and Treatments

Diurnal variation in human tear enzymes

Fullard, R.J., Carney, L.G.·1984·Experimental Eye Research
DOI 10.1016/0014-4835(84)90134-9
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Abstract

A fluorometric technique for measuring the activities of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) in human tear fluid is described. Measurement of separate LDH and MDH activities during the day resulted in fluctuating values with no definite pattern. However, a consistent diurnal pattern emerged when the tear LDH/MDH ratio was measured for individual tear sample. The tear LDH/MDH ratio was highest upon waking, declining soon after to a stable level for the remainder of the day. Evidence for a corneal epithelial origin of tear LDH and MDH is discussed, as well as the ability of the technique to detect differences in the metabolic status of the epithelium between the open-eye and closed-eye environments. Possible causes of the elevation of the tear LDH/MDH ratio following lid closure are unbinding of intracellular M-type LDH within epithelial cells and increased cell membrane permeability, both processes occurring in response to reduced cellular energy content under the more hypoxic conditions of lid closure. Although the nature of the present experiment did not allow any conclusive statement, de novo LDH synthesis may also be contributing to the increased tear LDH/MDH ratio. Deliberate corneal epithelial surface disruption was found to have no quantifiable effect on the tear LDH/MDH ratio.

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Crossref · 10.1016/0014-4835(84)90134-9

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  • Sampling tears for in vitro diagnoses is associated with errors due to small sample volumes, ease of evaporation during sample collection, variations in tear production among individuals and throughout the day, and challenging collection methods that can affect sampled analyte concentrations.

    “Despite the demonstrated correlations, sampling tears for in vitro diagnoses is associated with several errors that are due to the following: first, small sample volumes102; second, ease of evaporation during sample collection; third, variations in tear production among individuals and throughout the day103; and lastly, challenging collection methods that can affect the sampled analyte concentra”

    From Wearable biosensors for healthcare monitoring (2019) · cites this paper as [103]

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Authors
Fullard, R. J., & Carney, L. G.
Affiliations
The University of Melbourne (AU)
Venue
Experimental Eye Research
Publisher
Elsevier BV
Published
1984-01
Volume
38
Issue
1
Pages
15-26
ISSN
0014-4835 (ISSN-L)
DOI
10.1016/0014-4835(84)90134-9
OpenAlex
W2082416747
Cited by
32
References
45
Citations by year
2026: 1 · 2025: 3 · 2022: 3 · 2021: 2 · 2020: 1 · 2019: 2 · 2017: 2 · 2016: 2
FWCI
1.28
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Experimental Eye Research (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Ocular Surface and Contact Lens
  • Health Sciences › Medicine › Physiology › Salivary Gland Disorders and Functions
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Ocular Disorders and Treatments
Keywords
tears, lactate dehydrogenase, malate dehydrogenase, diurnal variation, corneal epithelium, hypoxia, cell membrane permeability, epithelial metabolism, fluorometric enzyme assay
MeSH terms
Circadian Rhythm, Cornea, Epithelium, Eyelids, Fluorometry, Humans, L-Lactate Dehydrogenase, Malate Dehydrogenase, Tears, Corneal Injuries

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