Chronic obstructive pulmonary disease (COPD) is a complex disease with many patients suffering from cardiovascular comorbidity. However, cardiovascular diseases remain often undiagnosed in COPD.
Assessment of the retinal microvasculature can provide value in cardiovascular profiling of these patients. Retinal microvascular assessment carried out via a noninvasive eye exam represents an easy to use tool when examining patients with COPD. The purpose of this review was to provide an overview of studies assessing structural and functional changes in the retinal microvasculature of patients with COPD. Findings demonstrated that structural and functional microvascular changes were more common and severe in COPD patients as compared to non‐COPD controls, although few retinal investigations have been performed in patients with COPD. As cardiovascular comorbidities are highly prevalent in COPD, we advocate more research to investigate the value of an eye exam for microvascular phenotyping of COPD patients.
In addition, assessment of dynamic changes in retinal vessel diameter during flicker light stimulation can provide important functional information, as it is a measure of the vascular reactivity and reflects the endothelial function of the microcirculation (Heitmar & Summers 2012). Dysfunction of the endothelium, represented by a reduced flicker light‐induced vasodilatation, precedes the development of vascular changes, which can eventually result in cardiovascular events (Flammer et al. 2013). An impaired flicker light‐induced vasodilatation has already been demonstrated in patients with increased cardiovascular risk, such as diabetes, hypertension, obesity and dyslipidemia (Heitmar & Summers 2012; Lim et al. 2013). Furthermore, dynamic assessment of the orbital vessels, using colour Doppler ultrasonography, has demonstrated that changes in blood flow velocity and resistive index (RI), are associated with various vascular disorders, and have clinical importance for the prediction of coronary artery disease (Tranquart et al. 2003; Maruyoshi et al. 2010).
Structural and functional assessment of the vasculature of the eye is used in many epidemiological and clinical research settings and the aim of this paper is to bring together the information that is available on patients with COPD.
Structural and functional assessment of the vasculature of the eye has provided useful information in a myriad of epidemiological and clinical research settings, with the ability to provide value for cardiovascular risk prediction. Cardiovascular risk factors (e.g. hypertension, obesity, diabetes) are usually preceded by changes in the microvasculature. A substantial number of patients suffering from COPD have microvascular complications and are at risk for diabetes and cardiovascular diseases. Considering the utility of retinal imaging in other clinical domains, we suggest to also consider retinal imaging for better phenotyping COPD patients (Figure 1). However, our systematic analysis suggests that this field is largely unexplored, and longitudinal studies assessing the association between microvascular changes in the eye and enhanced cardiovascular risk in COPD are lacking.
We identified four different methods for structural and functional assessment of the vasculature of the eye: OCT, retinal fundus imaging, retinal oximetry or colour Doppler ultrasonography. Available data suggest the presence of structural and functional microvascular changes in eyes of patients with COPD, including increased retinal venular calibre, lower retinal arterial oxygen saturation, impaired haemodynamics and increased RI of the orbital vessels. Results on choroidal thickness are contradictory. Authors speculated that the changes in microvasculature are related to systemic inflammation and hypoxia in COPD. Indeed, both systemic inflammation and hypoxia play a role in the pathogenesis of cardiovascular diseases. We advocate studies focusing on the characterization of the retinal microvasculature in patients with COPD, including validation using echocardiography and electrocardiogram and repeated assessments to establish stability over time. Moreover, assessment during COPD exacerbations resulting in hospitalizations is of interest as these exacerbations are associated with an increased cardiovascular mortality. Considering the high prevalence and incidence of cardiovascular comorbidity in COPD patients, and the fact that cardiovascular comorbidities are often undiagnosed, retinal imaging techniques might be valuables tools for further cardiovascular phenotyping of patients with COPD, which may lead to better patient stratification and more individualized treatments.
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