Assessment of hemodynamic indices of conjunctival microvascular function in patients with coronary microvascular dysfunction

Jonathan Mailey , Julie Moore, Paul Brennan, Min Jing, Agnes Awuah, James McLaughlin, M. Andrew Nesbit, Tara C. B. Moore, Mark S. Spence

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Objective: Coronary microvascular dysfunction (CMD) is a cause of ischaemia with non-obstructive coronary arteries (INOCA). It is notoriously underdiagnosed due to the need for invasive microvascular function testing. We hypothesized that systemic microvascular dysfunction could be demonstrated non-invasively in the microcirculation of the bulbar conjunctiva in patients with CMD. Methods: Patients undergoing coronary angiography for the investigation of chest pain or dyspnoea, with physiologically insignificant epicardial disease (fractional flow reserve ≥0.80) were recruited. All patients underwent invasive coronary microvascular function testing. We compared a cohort of patients with evidence of CMD (IMR ≥25 or CFR <2.0); to a group of controls (IMR <25 and CFR ≥2.0). Conjunctival imaging was performed using a previously validated combination of a smartphone and slit-lamp biomicroscope. This technique allows measurement of vessel diameter and other indices of microvascular function by tracking erythrocyte motion. Results: A total of 111 patients were included (43 CMD and 68 controls). There were no differences in baseline demographics, co-morbidities or epicardial coronary disease severity. The mean number of vessel segments analysed per patient was 21.0 ± 12.8 (3.2 ± 3.5 arterioles and 14.8 ± 10.8 venules). In the CMD cohort, significant reductions were observed in axial/cross-sectional velocity, blood flow, wall shear rate and stress. Conclusion: The changes in microvascular function linked to CMD can be observed non-invasively in the bulbar conjunctiva. Conjunctival vascular imaging may have utility as a non-invasive tool to both diagnose CMD and augment conventional cardiovascular risk assessment.

Original languageEnglish
Article number104480
Pages (from-to)1-11
Number of pages12
JournalMicrovascular Research
Early online date20 Jan 2023
Publication statusPublished (in print/issue) - 31 May 2023

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© 2023 Elsevier Inc.

Copyright © 2023 Elsevier Inc. All rights reserved.


  • Microvascular angina
  • Microvascular dysfunction
  • Conjunctiva
  • Cardiovascular screening


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