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

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.

LanguageEnglish
Article number103907
Pages1-9
Number of pages9
JournalMicrovascular Research
Volume126
Early online date19 Jul 2019
DOIs
Publication statusE-pub ahead of print - 19 Jul 2019

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Microcirculation
Smartphones
Hemodynamics
Electric lamps
Blood Volume
Shear deformation
Blood
Conjunctiva
Image registration
Malus
Microvessels
Charge coupled devices
Blood Vessels
Image processing
Smartphone
Slit Lamp
Imaging techniques
Equipment and Supplies

Keywords

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

Cite this

Brennan, Paul ; McNeil, Andrew ; Jing, Min ; Awuah, Agnes ; Finlay, Dewar ; Blighe, Kevin ; McLaughlin, James ; Wang, Ruixuan ; Moore, Jonathan ; Nesbit, M. Andrew ; Trucco, Emanuele ; Spence, Mark ; Moore, Tara C. B. / Quantitative assessment of the conjunctival microcirculation using a smartphone and slit-lamp biomicroscope. In: Microvascular Research. 2019 ; Vol. 126. pp. 1-9.
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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.",
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Quantitative assessment of the conjunctival microcirculation using a smartphone and slit-lamp biomicroscope. / Brennan, Paul; McNeil, Andrew ; Jing, Min; Awuah, Agnes; Finlay, Dewar; Blighe, Kevin; McLaughlin, James; Wang, Ruixuan ; Moore, Jonathan ; Nesbit, M. Andrew; Trucco, Emanuele; Spence, Mark ; Moore, Tara C. B.

In: Microvascular Research, Vol. 126, 103907, 01.11.2019, p. 1-9.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Quantitative assessment of the conjunctival microcirculation using a smartphone and slit-lamp biomicroscope

AU - Brennan, Paul

AU - McNeil, Andrew

AU - Jing, Min

AU - Awuah, Agnes

AU - Finlay, Dewar

AU - Blighe, Kevin

AU - McLaughlin, James

AU - Wang, Ruixuan

AU - Moore, Jonathan

AU - Nesbit, M. Andrew

AU - Trucco, Emanuele

AU - Spence, Mark

AU - Moore, Tara C. B.

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Y1 - 2019/7/19

N2 - 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.

AB - 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.

KW - Conjunctival circulation

KW - Endothelial dysfunction

KW - Haemodynamic assessment

KW - Microcirculation

KW - Smartphone

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