Are Retinal Microvascular Caliber Changes Associated with Severity of Coronary Artery Disease in Symptomatic Cardiac Patients?
Andreas KreisThanh T. NguyenJie Jin WangSophie RogersA. Al-FiadhMelanie FreemanTien Yin WongH.M. Omar Farouque
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Abstract:
Recent population-based studies have shown that retinal vascular caliber may predict the risk of clinical coronary artery disease (CAD) events. Whether this association is related to macro- or microvascular mechanisms remains unknown. We investigated the relationship of retinal vascular caliber with severity and extent of CAD in symptomatic cardiac patients.Overall, 98 patients attending diagnostic coronary angiography were recruited. Coronary angiography was used to assess for the severity and extent of CAD. Digital retinal photography was performed immediately prior to cardiac catheterization, and retinal vascular caliber was measured from these photographs by using a computer program and summarized as central retinal arteriolar (CRAE) and venular (CRVE) equivalents.Retinal arteriolar and venular calibers were not associated with increasing severity of CAD, as assessed by Leaman scores (CRAE/CRVE: P for trend=0.17/0.57), presence of clinically significant CAD (CRAE/CRVE: P=0.35/0.32), or number of diseased vessels (CRAE/CRVE: P for trend=0.18/0.69).Retinal vascular caliber changes are not associated with the severity of obstructive CAD in symptomatic patients. These data suggest that the association of retinal vascular caliber with clinical CAD seen in epidemiological studies may not be applicable to clinical symptomatic patients and may be related to microvascular, rather than macrovascular, mechanisms.Keywords:
Caliber
Retinal Artery
Central retinal artery
The aim of this study was to investigate whether retinal vasculature changes had occurred (retinal artery diameter, retinal vein diameter and artery/vein ratio) in patients with varicocele. This pilot study included 50 healthy subjects with any eye disease apart from slight refractive errors and 55 patients with varicocele. Retinal arteriolar and venular diameters were measured and summarised as central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE). Retinal microvascular diameters and the arteriolar-to-venular ratio (AVR) were assessed with a digital retinal camera. All measurements and calculations were performed using a computer-based program. The mean CRAE value was 151.8 ± 3.6 μm in the study group and 150.4 ± 4.5 μm in the control group. Mean CRVE value was 209.4 ± 5.9 μm in the study group and 200.1 ± 8.7 μm in the control group. AVR was found 0.72 ± 0.02 in the study group and 0.75 ± 0.03 in the control group. There were significant differences between groups in terms of CRVE and AVR. There were no significant differences between groups in terms of CRAE. The results of this study showed that the patients with varicocele showed significant changes on retinal vascular diameter.
Central retinal artery
Retinal Artery
Retinal Vein
Central retinal vein
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Commercially available platforms show good agreement in clinical outcomes for retinal vessel caliber measurements, despite differing absolute values. Tighter agreement is observed when right and left eye data are averaged, suggesting an approach suitable for clinical practice.The purpose of this study was to compare the retinal vessel caliber measurements generated by different commercially available platforms and their associations with systemic blood pressure and age.A total of 209 participants were recruited from a UK optometric practice. After a routine eye examination, participants had disc-centered retinal photographs and systemic blood pressure taken. Retinal vessel calibers (central retinal artery equivalent, central retinal vein equivalent, and arteriovenous ratio) were calculated using both MONA REVA and VesselMap.An inverse Pearson correlation was observed between central retinal artery equivalent and mean arterial blood pressure on both platforms (r = -0.275 [P ≤ .001] and r = -0.388 [P ≤ .001] for MONA REVA and VesselMap, respectively); this correlation was also observed with arteriovenous ratio and blood pressure. An inverse correlation was observed between central retinal artery equivalent and age (r = -0.362 [P ≤ .001] and r = -0.404 [P ≤ .001] for MONA REVA and VesselMap, respectively); this was also seen between central retinal vein equivalent and age (r = -0.322 [P ≤ .001] and r = -0.369 [P ≤ .001]). Arteriovenous ratio remained independent from age for both platforms. Bland-Altman plots demonstrated good agreement between the platforms for all three variables.Although absolute caliber measurements differed between the platforms, the correlations observed were of similar magnitudes, with good agreement between the two platforms. Tighter spaced limits of agreement were observed when right and left eye data were averaged for each subject. In the absence of localized ocular pathology, this approach should be used.
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Central retinal artery
Central retinal vein
Retinal Artery
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Caliber
Central retinal artery
Retinal Vein
Central retinal vein
Grading (engineering)
Retinal Artery
Fundus (uterus)
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Automated retinal artery and vein identification is a necessity to measure their caliber automatically and to achieve high efficiency and repeatability for a large number of images. In this paper, a novel framework for retinal artery and vein classification is provided. The proposed method utilizes the vessel crossover and color intensity profile which are the most significant features for artery and vein classification. The method first extracts retinal vascular network and then identify individual blood vessels for further classification as artery or vein. We apply deep learning algorithm based segmentation method to extract the retinal vascular network. We then identify each blood vessels to measure caliber that will be used for computing the Central Retinal Artery Equivalent (CRAE) and Central Retinal Vein Equivalent (CRVE). We map the vessel network and use the individual vessel crossover information, vessel color and intensity profile to identify individual vessel segment as artery and vein. We compared automatically classified artery and vein results with a human grader which showed an accuracy of 95%. We compare our results of caliber grading against an established semi-automated caliber grading system and protocol which showed a very high correlation of 0.85 and 0.92, for CRAE and CRVE respectively.
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Central retinal artery
Retinal Artery
Central retinal vein
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Retinal Vein
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We aimed to establish whether the change in retinal microvascular structure observed cross-sectionally with axial elongation and larger corneal curvature is comparable from early childhood to adolescence.In all, 1077 Sydney Paediatric Eye Study participants (36 to <72 months of age) and 1740, 2353, and 1216 from the Sydney Childhood Eye Study (6, 12, and 17 years of age), respectively, were examined. Quantifiable retinal vascular caliber measurements were obtained using validated computer-based methods. Ocular biometry measurements were performed according to standardized protocols.After multivariable adjustment, in children 36 to <72 months of age, each 1.0-mm increase in axial length was associated with a 3.67- and 6.53-μm narrowing of mean retinal arteriolar caliber (P = 0.005) and venular caliber (P < 0.0001), respectively. Each 1.0-mm increase in axial length in children 6, 12, and 17 years of age was associated with a 5.30-, 3.96-, and 4.03-μm decrease in mean retinal arteriolar caliber, respectively. Each 1.0-mm increase in axial length in children 6, 12, and 17 years of age was associated with a 7.12-, 6.72-, and 6.85-μm decrease in retinal venular caliber, respectively. Corneal curvature was inversely associated with retinal vascular caliber among all age groups (P < 0.001). Among those without significant refractive error (>0.00 and <2.00 diopters), significant inverse associations were observed between axial length and corneal curvature with retinal vessel caliber among all age groups.We demonstrate a similar magnitude of retinal vessel narrowing with axial length elongation and increasing corneal curvature from childhood through to adolescence. These data confirm the robustness of the associations between ocular biometric traits and retinal microvascular structural changes during childhood development.
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Retinal Artery
Central retinal vein
Caliber
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Changes in retinal vascular parameters have been shown to be associated with systemic vascular diseases. In this study, we assessed the physiologic variations in retinal vascular measurements during the cardiac cycle.Fundus images were taken using electrocardiogram-synchronized retinal camera at nine distinct cardiac points from 15 healthy volunteers (135 images). Analyses of retinal vessel geometric measures, including retinal vessel caliber (individual and summary), tortuosity, branching angle, length-diameter ratio (LDR), and optimality deviation, were performed using semiautomated computer software. Repeated-measures ANOVAs were used to obtain the means and to estimate the variation of each cardiac point compared with cardiac point 1.There was a significant variation of the caliber of the individual arteriolar and venular vessels. However, there was no significant variation found for vessel caliber summary, represented by the central retinal arteriolar equivalent (CRAE) and the central retinal venular equivalent (CRVE). There was also no significant variation found for tortuosity and branching angle, and LDR showed none or very little variations at different cardiac points: variations in caliber ranges between 0 and 4.1%, tortuosity 0 and 1.5%, branching angle 0 and 3.5%, and LDR 0 and 2%; all values for variations, P > 0.1; linear trend, P > 0.5; and nonlinear trend, P > 0.8.This study showed that there were minimal variations in the CRAE, CRVE, tortuosity, and branching angle that are clinically used for two-dimensional measures of retinal vascular geometry during cardiac cycles. However, there was significant variation in the caliber of the individual vessels over the cardiac cycle.
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Cardiac cycle
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Purpose. The aim of the present study was to calculate the diameter of the central retinal artery from results as obtained with non-invasive techniques in healthy young subjects. Methods. Twenty-four healthy male subjects participated in this study. Total retinal blood flow was calculated from combined bi-directional laser Doppler velocimetry and measurement of retinal venous diameters using the Zeiss retinal vessel analyzer. Using these techniques red blood cell velocity and vessel diameters of all visible veins entering the optic nerve head were measured and total retinal blood flow was calculated. Blood flow velocity in the central retinal artery was measured with color Doppler imaging. Form these outcome parameters the diameter of the central retinal artery was calculated for each subject individually. Results. In the present study cohort the mean retinal blood flow was 38.1 ± 9.1µl/min and the mean flow velocity in the central retinal artery was 6.3 ± 1.2 cm/s. From these data we calculated a mean diameter of the central retinal artery of 163 ± 17µm. Conclusions. Our results are in good agreement with data obtained from in vitro studies. The data of the present study also indicate that one needs to be careful to interpret velocity data from the central retinal artery in terms of retinal blood flow.
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Retinal Artery
Central retinal vein
Optic disc
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Objective To study the relationship between central retinal thickness and retinal vascular filling state of patients with non-proliferative diabetic retinopathy (NPDR).Methods A total of 248 diabetic patients without retinopathy or with NPDR in the hospital were enrolled in the study.Only the right eye of these patients were examined by optical coherence tomography (OCT),fundus fluorescein angiography (FFA),color Doppler flow imaging (CDFI).Patients with central retinal edema,hemorrhage and exudation were excluded from this study.Central retinal thickness was measured by OCT at the points of 1 mm,1 to 3 mm,and 3 to 6 mm from the fovea.The patients were divided into retinal thickness normal,thinning and thickening groups according to their central retinal thickness.The normal range of central retinal thickness was defined as 216.4-304.9 μm in this study.The arm retinal circulation time and retinal arterial phase and venous phase (A-V) fluorescence filling time were recorded by FFA examination.The peak systolic velocity (PSV),pulsatility index (PI) and resistance index (RI) of ophthalmic artery (OA),central retinal artery (CRA) and posterior ciliary artery (PCA) were measured by CDFI examination.The retinal fundus vascular filling state and ocular hemodynamic indexes were compared between different groups.Results The arm retinal circulation time of retinal thickness normal,thinning,thickening groups was (10.42±0.51),(10.36±0.64),(12.94±0.46) seconds respectively; the retinal A-V fluorescence filling time was (9.15±1.36),(6.36±1.15),(13.56±2.04) seconds.The difference of the arm retinal circulation time was statistically significant between the thickening and normal groups (t=1.93,P=0.04),and between the thickening and thinning groups (t=4.49,P=0.00).The retinal A-V fluorescence filling time was statistically significant between the thinning and normal groups (t=2.13,P=0.03),and between the thickening and normal groups (t=2.49,P=0.02),and between the thickening and thinning groups (t=5.38,P=0.00).The difference of PSV (t=3.290,-5.520,-4.900),PI (t=-4.310,-5.230,-4.390) and RI (t=4.970,6.160,5.990) of OA,CRA and PCA was statistically significant between the thickening and thinning groups (P＜0.05).Conclusion Central retinal thickness can affect the retinal vascular filling state of diabetic patients without retinopathy or with NPDR.
Key words:
Retinal vessels/physiopathology; Fluorescein angiography; Diabetic retinopathy
Central retinal artery
Fundus (uterus)
Hypertensive retinopathy
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The aim of the present study was to investigate the association between ultrasound Doppler measurements of resistive index (RI) in the central retinal artery and retinal vascular resistance (R) assessed with laser Doppler velocimetry, vessel size measurement, and calculation of ocular perfusion pressure (PP) in healthy subjects. An increase in vascular resistance was induced by inhalation of 100% O(2). During hyperoxia no significant changes in PP were observed. Mean flow velocity in main retinal veins was reduced by -27.5 +/- 2.0%. The average decrease in diameter was -11.5 +/- 1.0%. R, which was calculated as the ratio of PP to flow rate, increased by 97.6 +/- 7.7%. RI increased as well, but the effect was much smaller (6.6 +/- 2.2%). In addition, a negative correlation was found between baseline values of R and RI (r = -0.83). During hyperoxia R and RI were not associated. In conclusion, our data indicate that RI as assessed with color Doppler imaging in the central retinal artery is not an adequate measure of R.
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Central retinal artery
Retinal Artery
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