Evidence map›Paper›PMID 30818036›Full record

ArticleThe ocular surface2019

Ellipsometry of human tears.

Ben J Glasgow

Abstract readComparative Study
PubMed Full text at PMC Publisher
In one paragraph

Article in The ocular surface, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 7 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
7citing papers in PubMed, 1 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

7 citing papers in PubMed, 1 synthesis or guideline pooled it.

  1. Pooled it
  2. Article
  3. Article
  4. Article
  5. Lipocalin-1 is the acceptor protein for phospholipid transfer protein in tears.Biochemical and biophysical research communications · 2021
    Article
  6. Author Response: Surface Area of the Exposed Eye.Investigative ophthalmology & visual science · 2021
    Article
  7. Evidence for Phospholipids on the Surface of Human Tears.Investigative ophthalmology & visual science · 2020
    Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

1 author.

Ben J GlasgowDepartment of Ophthalmology, Jules Stein Eye Institute, 100 Stein Plaza, University of California, Los Angeles, CA, 90095, USA; Department of Pathology and Laboratory Medicine, Jules Stein Eye Institute, 100 Stein Plaza, University of California, Los Angeles, CA, 90095, USA. Electronic address: bglasgow@mednet.ucla.edu.

Funding

Proteins in the Molecular Mechanisms of Tear Film FormationR01EY011224 · NEI · UNIVERSITY OF CALIFORNIA LOS ANGELES · PI GLASGOW, BEN J · 2001 to 2020
$6.8M
PROTEINS IN MOLECULAR MECHANISMS OF TEAR FILM FORMATIONR29EY011224 · NEI · UNIVERSITY OF CALIFORNIA LOS ANGELES · PI GLASGOW, BEN J · 1996 to 2000
$116k
NEI NIH HHS R01 EY011224NEI NIH HHS R29 EY011224
6 · The paper itself

Abstract

purposeThe outer surface layer of tears is presumably composed of lipid. The thickness of this layer is considered critical to retard evaporation. Prior thickness measurements differ widely. Advances in ellipsometry have availed more precise and accurate measurements for thin films. The range in thickness of the surface layer of tears was studied by ellipsometry to uncover the source of prior discrepancies.

methodsTear surface layers of normal and dry eye subjects were measured by in-vitro ellipsometry. Lateral and Z resolutions of ∼1 μm and 0.1 nm, were achieved respectively. Thicknesses were derived from matrices and a Levenberg-Marquardt multivariate regression algorithm to Fresnel equations for multi-layered films.

resultsEllipsometric measurements of pooled and individual human tears in-vitro revealed a larger overall range (0-500 nm) of surface film thicknesses than previously reported by any one study. Each sample showed thin areas (0-2.6 nm) with interspersed thicker regions (∼200-500 nm). Repeat measurements of a single donor collected at weekly intervals showed a broad range of surface thicknesses within and between samples. Thickness measurements from a dry eye subject overlapped that of normal subjects.

conclusionThe data show that published disparity in surface film thickness may be attributable to limitations of prior methodologies. The range and overlap of surface film thicknesses challenge less rigorous methodologies that claim to segregate normal and dry eye.

Indexed as

Dry Eye SyndromesHumansInterferometryLipid MetabolismMeibomian GlandsTearsdry eyeEllipsometryInterferometryLipid layer thicknessMeibomian lipidReflectometryTear thickness

Identifiers

PMID30818036
PMCPMC6529266

What OpenQuestion holds

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Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.