Correlation and Reproducibility of Retinal Vascular Geometric Measurements for Stereoscopic Retinal Images of the Same Eyes

Retinal small vessel dilatation in the systemic inflammatory response to surgery

Retinal microvascular calibre has been proposed as a predictor of cardiac events. Surgery is a major stimulus for inflammation which potentially affects small vessel calibre. This study examined the effects of surgery on retinal, and thus systemic, small vessel size, and the potentially confounding effect of surgery when retinal vessel calibre is used to predict cardiac risk in hospital patients. Consecutive participants were recruited from a preoperative assessment clinic at a teaching hospital. They provided demographic and clinical details, and underwent retinal imaging before and again, within 3 days after surgery, with a non-mydriatic retinal camera. Images were graded for vessel calibre using semi-automated software based on the Parr-Hubbard formula with Knudtson’s modification (IVAN, U Wisconsin). Differences were examined using Fisher’s exact test or a paired t-test, and calibre determinants identified from univariate and multiple linear regression analysis (STATA version 11.2). Sixty-eight participants (23 men, 34%) with a mean age of 55 ± 14.5 years, were recruited. Fourteen (21%) underwent a laparotomy which was considered major surgery and 54 (79%) had Other surgery. Mean C-reactive protein (CRP) levels increased post-operatively from 7.8 ± 20.2 mg/L to 43.9 ± 55.1 mg/L (p < 0.01), and mean serum albumin decreased from 38.9 ± 4.4 g/L to 33.9 ± 5.5 g/L (p < 0.01). Mean central retinal arteriole and venular equivalent calibre (CRAE, CRVE) increased post-operatively (142.4 ± 13.3 µm to 146.4 ± 13.0 µm, p < 0.01 and 213.1 ± 16.8 µm to 217.9 ± 18.3 µm, p < 0.01, respectively). The systemic microvasculature dilates post-operatively possibly secondary to inflammation and endothelial dysfunction. These changes were present within 3 days of surgery and may confound the use of small vessel calibre to predict cardiac risk in surgical inpatients. Microvascular dilatation in response to other inflammatory stimuli such as pneumonia is a known potential confounder in hospital patients.

[Retinal vascular network: Changes with aging and systemic vascular disease (cardiac and cerebral)]

For over 10 years, the description of the retinal microvascular network has benefited from the development of new imaging techniques. Automated retinal image analysis software, as well as OCT angiography (OCT-A), are able to highlight subtle, early changes in the retinal vascular network thanks to a large amount of microvascular quantitative data. The challenge of current research is to demonstrate the association between these microvascular changes, the systemic vascular aging process, and cerebrovascular and cardiovascular disease. Indeed, a pathophysiological continuum exists between retinal microvascular changes and systemic vascular diseases. In the Montrachet study, we found that a suboptimal retinal vascular network, as identified by the Singapore I Vessel Assessment (SIVA) software, was significantly associated with treated diabetes and an increased risk of cardiovascular mortality. In addition, we supplemented our research on the retinal vascular network with the use of OCT-A. In the EYE-MI study, we showed the potential role of quantitative characterization of the retinal microvascular network by OCT-A in order to assess the cardiovascular risk profile of patients with a history of myocardial infarction. A high AHA (American Heart Association) risk score was associated with low retinal vascular density independently of hemodynamic changes. Thus, a better understanding of the association between the retinal microvasculature and macrovascular disease might make its use conceivable for early identification of at-risk patients and to suggest a personalized program of preventative care. The retinal vascular network could therefore represent an indicator of systemic vascular disease as well as an interesting predictive biomarker for vascular events.

American Heart Association ideal cardiovascular health score and subclinical atherosclerosis in 22-35-year-old adults conceived with and without assisted reproductive technologies

STUDY QUESTION

Is ART related with the association of American Heart Association (AHA) ideal cardiovascular health score and markers of subclinical atherosclerosis?

SUMMARY ANSWER

The associations between AHA score and markers of subclinical atherosclerosis in ART and non-ART groups were similar in magnitude.

WHAT IS KNOWN ALREADY

Long-term consequences of ART on cardiovascular health are unknown.

STUDY DESIGN, SIZE, DURATION

The study cohort for the cross-sectional analyses consisted of 172 ART-conceived and 78 non-ART conceived individuals of same age (range 22-35 years).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cardiovascular risk factor status was evaluated with American Heart Association (AHA) ideal cardiovascular health score consisting of seven factors (body mass index, blood pressure, total cholesterol, glucose, diet and physical activity, non-smoking). Carotid artery intima-media thickness (cIMT), arterial pulse-wave velocity (PWV) and retinal microvascular parameters were evaluated as markers of early atherosclerosis. Group comparisons in continuous variables were performed with t-tests. For categorical variables, comparisons were performed with chi-square tests. The relationships between AHA score and the markers of atherosclerosis were examined with linear regression analyses adjusted for age and sex.

MAIN RESULTS AND THE ROLE OF CHANCE

There was no difference in AHA ideal health score between the ART and non-ART groups; mean (SD) scores were 4.1(1.4) versus 4.0(1.5), respectively, P = 0.65. No differences were observed between groups for any individual ideal health metric (P always >0.2). AHA score was not associated with cIMT or retinal measures in either group (P always >0.05). An inverse association was observed between AHA score and PWV in the ART group (beta (95% CI) -0.18(-0.26 to -0.10)). A numerically similar relationship was observed in the smaller non-ART group (-0.19(-0.39 to 0.01)).

LIMITATIONS, REASONS FOR CAUTION

Even though this cohort is among the largest ART studies with extensive cardiovascular data, the sample is still relatively small and the statistical power is limited. As the study population was still in early adulthood, we were not able to evaluate the associations with clinical cardiovascular events, but utilized non-invasive methods to assess early markers of subclinical atherosclerosis.

WIDER IMPLICATIONS OF THE FINDINGS

These findings suggest that ART-conceived individuals do not have increased vulnerability for cardiovascular risk factors.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by a National Health & Medical Research Council Project Grant (APP1099641), The Royal Children's Hospital Research Foundation, Monash IVF Research and Education Foundation, and Reproductive Biology Unit Sperm Fund, Melbourne IVF. The authors have no conflicts of interest relevant to this article to disclose.

Retinal Arteriolar Narrowing in Young Adults With Glaucomatous Optic Disc

PURPOSE

Glaucomatous optic disc (GOD) might represent various subclinical processes. However, whether the presence of GOD is related to vascular processes is less clear. This study aimed to assess the retinal vessel diameter, as surrogate markers of vascular regulation, in healthy young adults with GOD compared with normal.

MATERIALS AND METHODS

This was a clinic-based case-control study of 54 participants, aged between 18 and 30 years. We included patients with GOD (confirmed with slit-lamp and optical coherence tomography examination having cup-to-disc ratio ≥0.5), intraocular pressure ≤21 mm Hg, no history of hypertension, cardiovascular and kidney disease, anemia, diabetes mellitus, and spherical correction of ≤-1.5 D. Controls were healthy subjects with similar criteria but no sign of GOD. Retinal vessel diameters were measured using semiautomated program [Singapore I Vessel Assessment (SIVA) version 4.0] and expressed as central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent.

RESULTS

The mean CRAE was significantly narrower in patients with GOD than controls (110.6±12.16 vs. 118.6±12.17; P=0.019). Central retinal venular equivalent was not significantly different. A CRAE narrower than 107.1 μm was significantly associated with GOD (odds ratio, 8.59; 95% confidence interval, 1.68-43.9; P<0.001) compared with controls.

CONCLUSIONS

Retinal arterioles were narrower in young adults with GOD compared with normal, suggesting that the presence of GOD might be associated with subclinical changes in retinal vascularization even in the absence of increased intraocular pressure. However, the clinical significance of these findings deserves further studies.

Macro- and Microvascular Parameters After Toxic Shock Syndrome

Whether individuals who had toxic shock syndrome in childhood have differences in macro- and retinal microvascular parameters indicative of increased cardiovascular risk is unknown. We found no evidence of adverse macrovascular changes in 22 toxic shock syndrome participants compared with 60 control participants. Microvascular comparisons showed a reduction in retinal total fractal dimension, which has been associated with cardiovascular risk factors in children.

Association between the retinal vascular network with Singapore "I" Vessel Assessment (SIVA) software, cardiovascular history and risk factors in the elderly: The Montrachet study, population-based study

Purpose

To identify patterns summarizing the retinal vascular network in the elderly and to investigate the relationship of these vascular patterns with cardiovascular history.

Methods

We conducted a population-based study, the Montrachet study (Maculopathy Optic Nerve nuTRition neurovAsCular and HEarT diseases), in participants older than 75 years. The history of cardiovascular disease and a score-based estimation of their 10-year risk of cardiovascular mortality (Heart SCORE) were collected. Retinal vascular network analysis was performed by means of Singapore “I” Vessel Assessment (SIVA) software. Principal component analysis was used to condense the information contained in the high number of variables provided and to identify independent retinal vascular patterns.

Results

Overall, 1069 photographs (1069 participants) were reviewed with SIVA software. The mean age was 80.0 ± 3.8 years. We extracted three vascular patterns summarizing 41.3% of the vascular information. The most clinically relevant pattern, Sparse vascular network, accounted for 17.4% of the total variance. It corresponded to a lower density in the vascular network and higher variability in vessel width. Diabetic participants with hypoglycemic treatment had a sparser vascular network pattern than subjects without such treatment (odds ratio, [OR], 1.68; 95% CI, 1.04–2.72; P = 0.04). Participants with no history of cardiovascular disease who had a sparser vascular network were associated with a higher Heart SCORE (OR, 1.76; 95% CI, 1.08–2.25; P = 0.02).

Conclusions

Three vascular patterns were identified. The Sparse vascular network pattern was associated with having a higher risk profile for cardiovascular mortality risk at 10 years.

Reproducibility of Retinal Microvascular Traits Decoded by the Singapore I Vessel Assessment Software Across the Human Age Range

BACKGROUND

Retinal microvascular traits predict adverse health outcomes. The Singapore I Vessel Assessment (SIVA) software improved automated postprocessing of retinal photographs. In addition to microvessel caliber, it generates measures of arteriolar and venular geometry. Few studies addressed the reproducibility of SIVA measurements across a wide age range.

METHODS

In the current study, 2 blinded graders read images obtained by nonmydriatic retinal photography twice in 20 11-year-old children, born prematurely (n = 10) or at term (n = 10) and in 60 adults (age range, 18.9–86.1 years).

RESULTS

Former preterm compared with term children had lower microvessel diameter and disorganized vessel geometry with no differences in intraobserver and interobserver variability. Among adults, microvessel caliber decreased with age and blood pressure and arteriolar geometry was inversely correlated with female sex and age. Intraobserver differences estimated by the Bland–Altman method did not reach significance for any measurement. Across measurements, median reproducibility (RM) expressed as percent of the average trait value was 8.8% in children (median intraclass correlation coefficient [ICC], 0.94) and 8.0% (0.97) in adults. Likewise, interobserver differences did not reach significance with RM (ICC) of 10.6% (0.85) in children and 10.4% (0.93) in adults. Reproducibility was best for microvessel caliber (intraobserver/interobserver RM, 4.7%/6.0%; ICC, 0.98/0.96), worst for venular geometry (17.0%/18.8%; 0.93/0.84), and intermediate for arteriolar geometry (10.9%/14.9%; 0.95/0.86).

CONCLUSIONS

SIVA produces repeatable measures of the retinal microvasculature in former preterm and term children and in adults, thereby proving its usability from childhood to old age.

Retinal vascular imaging technology to monitor disease severity and complications in type 1 diabetes mellitus: A systematic review

OBJECTIVE

Type 1 diabetes mellitus (T1DM) is a major disease affecting a large number of young patients. In the recent years, retinal vascular imaging has provided an objective assessment of vascular health in patients with T1DM. Our study aimed to review the current literature on retinal vascular parameters in young patients with T1DM in order to understand the following: (i) How retinal vessels are affected in T1DM (ii) How such vascular changes can be predictive of future diabetic microvascular complications METHODS: We performed a systematic review and extracted relevant data from 17 articles.

RESULTS

We found significant correlations between retinal vessel changes and diabetes-related risk factors (eg, hypertension, hyperlipidemia, and obesity), diabetes-related features (eg, diabetes duration and glycemic control), and diabetes-related microvascular complications (eg, diabetic retinopathy, nephropathy, and neuropathy).

CONCLUSION

Our findings suggest that retinal microvasculature is associated with both disease severity and complications in young patients with T1DM.

Evidence of Microvascular Changes in the Retina following Kawasaki Disease

It is unclear whether all children with Kawasaki disease (KD) have increased later cardiovascular risk. The retinal microvasculature reflects changes in the microcirculation and is associated with traditional cardiovascular risk factors and events. The aim of this study was to investigate retinal microvascular parameters in two populations of patients with previous KD and control participants. We performed case-control studies of 116 (57 patients and 59 control participants) Australian and 156 (78 patients and 78 control participants) Singaporean individuals, at least two years since their acute illness. Standardised retinal photographs were graded by trained technicians using a semi-automated software, which quantifies the retinal microvasculature (calibre, branching angle, fractal dimensions, and tortuosity). Retinal venules of Singaporean KD patients were 9.67 μm (95% CI 4.87 to 14.51, p < 0.001) larger than control participants following correction for traditional cardiovascular risk factors. An incremental increase in the size of retinal venules in those with coronary artery abnormalities was observed. There was limited evidence that retinal venules were larger in Australian KD patients with coronary artery abnormalities compared to control participants (7.34 μm, 95% CI 1.30 to 15.99, p = 0.10). Differences in retinal microvasculature were particularly evident in Singaporean KD patients. Larger retinal venules may reflect chronic inflammation and endothelial dysfunction, and are associated with coronary artery disease in adults.