Quantitative assessment of the conjunctival microcirculation using a smartphone and slit-lamp biomicroscope

Paul Brennan, Andrew McNeil, Min Jing, Agnes Awuah, Dewar Finlay, Kevin Blighe, James McLaughlin, Ruixuan Wang, Jonathan Moore, M. Andrew Nesbit, Emanuele Trucco, Mark Spence, Tara C. B. Moore

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Purpose: The conjunctival microcirculation is a readily-accessible vascular bed for quantitative haemodynamic assessment and has been studied previously using a digital charge-coupled device (CCD). Smartphone video imaging of the conjunctiva, and haemodynamic parameter quantification, represents a novel approach. We report the feasibility of smartphone video acquisition and subsequent haemodynamic measure quantification via semi-automated means. Methods: Using an Apple iPhone 6 s and a Topcon SL-D4 slit-lamp biomicroscope, we obtained videos of the conjunctival microcirculation in 4 fields of view per patient, for 17 low cardiovascular risk patients. After image registration and processing, we quantified the diameter, mean axial velocity, mean blood volume flow, and wall shear rate for each vessel studied. Vessels were grouped into quartiles based on their diameter i.e. group 1 (<11 μm), 2 (11–16 μm), 3 (16–22 μm) and 4 (>22 μm). Results: From the 17 healthy controls (mean QRISK3 6.6%), we obtained quantifiable haemodynamics from 626 vessel segments. The mean diameter of microvessels, across all sites, was 21.1μm (range 5.8–58 μm). Mean axial velocity was 0.50mm/s (range 0.11–1mm/s) and there was a modestly positive correlation (r 0.322) seen with increasing diameter, best appreciated when comparing group 4 to the remaining groups (p < .0001). Blood volume flow (mean 145.61pl/s, range 7.05–1178.81pl/s) was strongly correlated with increasing diameter (r 0.943, p < .0001) and wall shear rate (mean 157.31 s 1, range 37.37–841.66 s 1) negatively correlated with increasing diameter (r − 0.703, p < .0001). Conclusions: We, for the first time, report the successful assessment and quantification of the conjunctival microcirculatory haemodynamics using a smartphone-based system.

Original languageEnglish
Article number103907
Pages (from-to)1-9
Number of pages9
JournalMicrovascular Research
Volume126
Early online date19 Jul 2019
DOIs
Publication statusPublished - 1 Nov 2019

Keywords

  • Conjunctival circulation
  • Endothelial dysfunction
  • Haemodynamic assessment
  • Microcirculation
  • Smartphone

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