Retinal Vascular Measurements Research Articles

CF-Loss: Clinically-relevant feature optimised loss function for retinal multi-class vessel segmentation and vascular feature measurement

Characterising clinically-relevant vascular features, such as vessel density and fractal dimension, can benefit biomarker discovery and disease diagnosis for both ophthalmic and systemic diseases. In this work, we explicitly encode vascular features into an end-to-end loss function for multi-class vessel segmentation, categorising pixels into artery, vein, uncertain pixels, and background. This clinically-relevant feature optimised loss function (CF-Loss) regulates networks to segment accurate multi-class vessel maps that produce precise vascular features. Our experiments first verify that CF-Loss significantly improves both multi-class vessel segmentation and vascular feature estimation, with two standard segmentation networks, on three publicly available datasets. We reveal that pixel-based segmentation performance is not always positively correlated with accuracy of vascular features, thus highlighting the importance of optimising vascular features directly via CF-Loss. Finally, we show that improved vascular features from CF-Loss, as biomarkers, can yield quantitative improvements in the prediction of ischaemic stroke, a real-world clinical downstream task. The code is available at https://github.com/rmaphoh/feature-loss.

Comparative analysis of optical coherence tomography angiography (OCTA) results between Behçet's disease patients and a healthy control group.

This study aimed to compare optical coherence tomography angiography (OCTA) findings between patients with Behçet's disease (BD) and individuals with healthy eyes. A cross-sectional study. This cross-sectional study was conducted on patients (67 eyes) with BD who were referred to Feiz Hospital and healthy eyes (43 eyes). All subjects underwent Snellenvisualacuity, a slit-lamp examination, measuring intraocular pressure, conducting a dilated fundus examination, OCTA imaging, and spectral-domain (SD)-OCT imaging. OCTA retinal vascular measurements including optic nerve VD, macular-associated VD( superficial and deep), foveal avascular zone (FAZ) area, FAZ perimeter (PERIM), and vessel density within a 300-μm-wide region of the FAZ (FD) were compared between the groups. A significant difference was evident between the two groups (healthy one group and BD group) in terms of parafoveal and perifoveal total retinal thickness, total pRNFL VD in all quadrants except the inferior sector (P < 0.05), and macular superficial, and deep VD in all regions except temporal and superior perifoveal VD (P < 0.05) following adjustments for age, gender, and signal strength index. When comparing the two groups, ocular Behçet's disease (BD) and non-ocular BD, it was evident that peripapillary vessel density (VD) exhibited a significant decrease in ocular BD eyes in all sectors except for the superior and inferior ones, as compared to non-ocular BD eyes. In addition, the comparison of ocular BD and non-ocular BD showed superficial and deep VDs were lower in ocular BD than non-ocular BD in all regions. According to these findings, peripapillary and macular vessel density is affected in BD. Key Points • The study utilized OCTA to compare retinal features in Behçet's disease (BD) patients and healthy individuals, revealing significant differences in retinal thickness and vessel density. • Ocular BD demonstrated reduced peripapillary vessel density compared to non-ocular BD. • The demonstrated association between ADMA and cIMT in patients with early SSc may suggest a role of NO/ADMA pathway in the initiation of macrovascular injury in SSc.

Retinal Vascular Measurements and Mortality Risk: Evidence From the UK Biobank Study.

This study aimed to investigate the association between quantitative retinal vascular measurements and the risk of all-cause and premature mortality. In this population-based cohort study using the UK Biobank data, we employed the Retina-based Microvascular Health Assessment System to assess fundus images for image quality and extracted 392 retinal vascular measurements per fundus image. These measurements encompass six categories of vascular features: caliber, density, length, tortuosity, branching angle, and complexity. Univariate Cox regression models were used to identify potential indicators of mortality risk using data on all-cause and premature mortality from death registries. Multivariate Cox regression models were then used to test these associations while controlling for confounding factors. The final analysis included 66,415 participants. After adjusting for demographic, health, and lifestyle factors and genetic risk score, 18 and 10 retinal vascular measurements were significantly associated with all-cause mortality and premature mortality, respectively. In the fully adjusted model, the following measurements of different vascular features were significantly associated with all-cause mortality and premature mortality: arterial bifurcation density (branching angle), number of arterial segments (complexity), interquartile range and median absolute deviation of arterial curve angle (tortuosity), mean and median values of mean pixel widths of all arterial segments in each image (caliber), skeleton density of arteries in macular area (density), and minimum venular arc length (length). The study revealed 18 retinal vascular measurements significantly associated with all-cause mortality and 10 associated with premature mortality. Those identified parameters should be further studied for biological mechanisms connecting them to increased mortality risk. This study identifies retinal biomarkers for increased mortality risk and provides novel targets for investigating the underlying biological mechanisms.

Macular vessel density in the superficial plexus is not associated to cerebrovascular damage in non‐demented individuals: data from the NORFACE cohort

AbstractBackgroundOptical Coherence Tomography angiography (OCT‐A) is a novel tool that allows the detection of retinal vascular changes. The comparison of OCT‐A measures with brain vascular burden is essential to validate the former as a surrogate of cerebrovascular damage and biomarker of cognitive decline. We aimed to investigate the association of macular vessel density (VD) in the superficial plexus assessed by OCT‐A with measures of cerebrovascular pathology quantified by brain magnetic resonance imaging (MRI) in a cohort of non‐demented individuals.MethodClinical, demographical, APOE ε4 status, amyloid status, OCT‐A and brain MRI data from non‐demented participants of the FACEHBI and BIOFACE studies were included. We analyzed the association of macular VD in four quadrants (superior, nasal, inferior and temporal) with brain vascular burden using the Fazekas scale scores (dichotomized in two categories, 0‐1 vs 2‐3), assessed in a logistic regression analysis, and the volume of white matter hyperintensities (WMH) quantified by Freesurfer assessed in a multiple regression analysis. We additionally explored the associations of macular VD with hippocampal volume, ventricles volume and Alzheimer Disease cortical signature (ADCS) thickness assessed in a multiple regression analysis. All analyses were adjusted for age and dyslipidemia.ResultThe study cohort comprised 188 participants: 89 with subjective cognitive decline (SCD) and 99 with mild cognitive impairment (MCI). Logistic regression analysis showed no significant differences of regional macular VD between the two Fazekas groups (all, p&gt;0.05). Multiple regression analysis showed no significant association of regional macular VD with the volume of WMH (all, p&gt;0.05). Macular VD in the nasal and inferior quadrants were positively associated with hippocampal volume (p = 0.009 and p = 0.021, respectively), but no association was detected with ventricles volume or ADCS thickness (both p&gt;0.05).ConclusionOur study showed that retinal vascular measures (regional macular VD in the superficial vascular plexus) assessed by OCT‐A were not associated with brain vascular damage quantified by the Fazekas scale and the WMH burden n in a cohort of non‐demented research participants with SCD and MCI.

Variability in Capillary Perfusion Is Increased in Regions of Retinal Ischemia Due to Branch Retinal Vein Occlusion.

To investigate alterations in macular perfusion variability due to branch retinal vein occlusion (BRVO) using a novel approach based on optical coherence tomography angiography (OCTA) coefficient of variation (CoV) analysis. Thirteen eyes of 13 patients with macular ischemia due to BRVO were studied. Multiple consecutive en face OCTA images were acquired. Bias field correction, spatial alignment, and normalization of intensities across the images were performed followed by pixelwise computation of standard deviation divided by the mean to generate a CoV map. Region of interest-based CoV values, derived from this map, for arterioles, venules, and the microvasculature were compared between regions with macular ischemia and control areas of the same eye. Control areas were regions of the same macula that were not affected by the BRVO and had normal retinal vascular structure as seen on multimodal imaging and normal retinal vascular density measurements as quantified using OCTA. CoV increased by a mean value of 17.6% within the microvasculature of ischemic regions compared to the control microvasculature (P < 0.0001). CoV measurements of microvasculature were consistently greater in the ischemic area of all 13 eyes compared to control. There were no differences in CoV measurements between ischemic and control areas for arterioles (P = 0.13) and venules (P = 1.0). Greater variability in microvasculature perfusion occurs at sites of macular ischemia due to BRVO. We report a novel way for quantifying macular perfusion variability using OCTA. This technique may have applicability for studying the pathophysiology of other retinal vascular diseases.

Comprehensive retinal vascular measurements: time in range is associated with peripheral retinal venular calibers in type 2 diabetes in China.

Retinal vascular parameters are biomarkers of diabetic microangiopathy. We aimed to investigate the relationship between time in range (TIR) assessed by continuous glucose monitoring (CGM) and retinal vascular parameters in patients with type 2 diabetes in China. The TIR assessed by CGM and retinal photographs were obtained at the same time from adults with type 2 diabetes who were recruited. Retinal vascular parameters were extracted from retinal photographs by a validated fully automated computer program, and TIR was defined as between 3.9-7.8mmol/L over a 24-h period. The association between TIR and caliber of retinal vessels distributed in different zones were analyzed using multivariable linear regression analyses. For retinal vascular parameters measurements, the peripheral arteriovenous and middle venular calibers widen with decreasing TIR quartiles (P < 0.05). Lower TIR was associated with wider peripheral venule after adjusting for potential confounders. Even after further correction for GV, there was still a significant correlation between TIR and peripheral vascular calibers (CV: β = - 0.015 [- 0.027, - 0.003], P = 0.013; MAGE: β = - 0.013 [- 0.025, - 0.001], P = 0.038) and SD: β = - 0.013 [- 0.026, - 0.001], P = 0.004). Similar findings were not found for the middle and central venular calibers or arterial calibers located in different zones. The TIR was associated with adverse changes to peripheral retinal venules but not central and middle vessels in patients with type 2 diabetes, suggesting that peripheral retinal vascular calibers may be affected by glycemic fluctuations earlier.

Combining retinal structural and vascular measurements improves discriminative power for multiple sclerosis patients.

Data on how retinal structural and vascular parameters jointly influence the diagnostic performance of detection of multiple sclerosis (MS) patients without optic neuritis (MSNON) are lacking. To investigate the diagnostic performance of structural and vascular changes to detect MSNON from controls, we performed a cross-sectional study of 76 eyes from 51 MS participants and 117 eyes from 71 healthy controls. Retinal macular ganglion cell complex (GCC), retinal nerve fiber layer (RNFL) thicknesses, and capillary densities from the superficial (SCP) and deep capillary plexuses (DCP) were obtained from the Cirrus AngioPlex. The best structural parameter for detecting MS was compensated RNFL from the optic nerve head (AUC = 0.85), followed by GCC from the macula (AUC = 0.79), while the best vascular parameter was the SCP (AUC = 0.66). Combining structural and vascular parameters improved the diagnostic performance for MS detection (AUC = 0.90; p<0.001). Including both structure and vasculature in the joint model considerably improved the discrimination between MSNON and normal controls compared to each parameter separately (p = 0.027). Combining optical coherence tomography (OCT)-derived structural metrics and vascular measurements from optical coherence tomography angiography (OCTA) improved the detection of MSNON. Further studies may be warranted to evaluate the clinical utility of OCT and OCTA parameters in the prediction of disease progression.

Relationships between quantitative retinal microvascular characteristics and cognitive function based on automated artificial intelligence measurements.

Introduction: The purpose of this study is to assess the relationship between retinal vascular characteristics and cognitive function using artificial intelligence techniques to obtain fully automated quantitative measurements of retinal vascular morphological parameters. Methods: A deep learning-based semantic segmentation network ResNet101-UNet was used to construct a vascular segmentation model for fully automated quantitative measurement of retinal vascular parameters on fundus photographs. Retinal photographs centered on the optic disc of 3107 participants (aged 50-93years) from the Beijing Eye Study 2011, a population-based cross-sectional study, were analyzed. The main parameters included the retinal vascular branching angle, vascular fractal dimension, vascular diameter, vascular tortuosity, and vascular density. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). Results: The results showed that the mean MMSE score was 26.34 ± 3.64 (median: 27; range: 2-30). Among the participants, 414 (13.3%) were classified as having cognitive impairment (MMSE score < 24), 296 (9.5%) were classified as mild cognitive impairment (MMSE: 19-23), 98 (3.2%) were classified as moderate cognitive impairment (MMSE: 10-18), and 20 (0.6%) were classified as severe cognitive impairment (MMSE < 10). Compared with the normal cognitive function group, the retinal venular average diameter was significantly larger (p = 0.013), and the retinal vascular fractal dimension and vascular density were significantly smaller (both p < 0.001) in the mild cognitive impairment group. The retinal arteriole-to-venular ratio (p = 0.003) and vascular fractal dimension (p = 0.033) were significantly decreased in the severe cognitive impairment group compared to the mild cognitive impairment group. In the multivariate analysis, better cognition (i.e., higher MMSE score) was significantly associated with higher retinal vascular fractal dimension (b = 0.134, p = 0.043) and higher retinal vascular density (b = 0.152, p = 0.023) after adjustment for age, best corrected visual acuity (BCVA) (logMAR) and education level. Discussion: In conclusion, our findings derived from an artificial intelligence-based fully automated retinal vascular parameter measurement method showed that several retinal vascular morphological parameters were correlated with cognitive impairment. The decrease in retinal vascular fractal dimension and decreased vascular density may serve as candidate biomarkers for early identification of cognitive impairment. The observed reduction in the retinal arteriole-to-venular ratio occurs in the late stages of cognitive impairment.

Comparing Common Retinal Vessel Caliber Measurement Software with an Automatic Deep Learning System

Purpose To compare the Retina-based Microvascular Health Assessment System (RMHAS) with Integrative Vessel Analysis (IVAN) for retinal vessel caliber measurement. Methods Eligible fundus photographs from the Lingtou Eye Cohort Study were obtained alongside their corresponding participant data. Vascular diameter was automatically measured using IVAN and RMHAS software, and intersoftware variations were assessed by intra-class correlation coefficients (ICC), and 95% confidence intervals (CIs). Scatterplots and Bland–Altman plots assessed the agreement between programs, and a Pearson’s correlation test assessed the strength of associations between systemic variables and retinal calibers. An algorithm was proposed to convert measurements between software for interchangeability. Results ICCs between IVAN and RMHAS were moderate for CRAE and AVR (ICC; 95%CI)(0.62; 0.60 to 0.63 and 0.42; 0.40 to 0.44 respectively) and excellent for CRVE (0.76; 0.75 to 0.77). When comparing retinal vascular calibre measurements between tools, mean differences (MD, 95% confidence intervals) in CRAE, CRVE, and AVR were 22.34 (–7.29 to 51.97 µm),–7.01 (–37.68 to 23.67 µm), and 0.12 (–0.02 to 0.26 µm), respectively. The correlation of systemic parameters with CRAE/CRVE was poor and the correlation of CRAE with age, sex, systolic blood pressure, and CRVE with age, sex, and serum glucose were significantly different between IVAN and RMHAS (p < 0.05). Conclusions CRAE and AVR correlated moderately between retinal measurement software systems while CRVE correlated well. Further studies confirming this agreeability and interchangeability in large-scale datasets are needed before softwares are deemed comparable in clinical practice.

Retinal vessel geometry in patients with idiopathic epiretinal membrane

We investigated the associations between retinal vascular geometric measurements and idiopathic epiretinal membrane (ERM). Whether changes in retinal vascular geometry are independent of systemic cardiovascular risk factors was also evaluated. This retrospective, cross sectional study included 98 patients with idiopathic ERM, and 99 healthy age-matched controls. Quantitative retinal vascular parameters were measured from digital retinal fundus photographs using a semi-automated computer-assisted program. Multivariate logistic regression analyses were performed to evaluate associations between retinal vascular geometric parameters and the presence of idiopathic ERM after adjusting for systemic cardiovascular risk factors. There was no significant difference in the baseline characteristics of the two groups, except that the ERM group had a higher proportion of females than the control group. In multivariate regression analyses, female sex (odds ratio [OR] 0.402; 95% CI 0.196–0.802; P = 0.011), wider retinal venular caliber (OR 16.852; 95% CI 5.384–58.997; P < 0.001) and decreased total fractal dimension (OR 0.156; 95% CI 0.052–0.440; P = 0.001) were associated with idiopathic ERM. Idiopathic ERM was associated with alterations in global retinal microvascular geometric parameters, wider retinal venules, and less complex vascular branching patterns, independent of cardiovascular risk factors.

Changes in retinal vascular bifurcation in eyes with myopia

ObjectiveTo evaluate the effect of myopia on retinal vascular bifurcation.MethodsA cross-sectional study that retrospectively analyzed the fundus photographs and clinical data of 493 people who participated in routine physical examinations in Huadong Sanatorium. One eye of each subject was included in the analysis. Retinal vascular bifurcation measurements were extracted by using a validated computer program. One-way ANOVA and analysis of covariance were performed to compare the measurements across high myopia, low to moderate myopia, and non-myopia groups.ResultsThe mean age was 41.83 ± 10.43 years and 63.49% were women. The mean spherical equivalent refraction (SER) was − 4.59 ± 3.07 D. Ninety-nine (20.08%) eyes met the definition of high myopia (SER ≤ -6.0 D), along with 234 (47.46%) low to moderate myopia (-6.0 D < SER <-0.5 D), and 160 (32.45%) non-myopia (SER ≥ -0.5 D). The differences in the arteriolar branching angle, venular branching coefficient, venular asymmetry ratio, venular angular asymmetry, and venular junctional exponent among the three groups remained significant (p < 0.05) after multivariate adjustment. Pairwise comparisons showed arteriolar branching angle and venular angular asymmetry in high myopia were significantly lower than low to moderate myopia (p < 0.001, p = 0.014 respectively) and non-myopia (p = 0.007, p = 0.048 respectively). Venular asymmetry ratio and venular branching coefficient in high myopia were significantly higher than low to moderate myopia (p = 0.029, p = 0.001 respectively) and non-myopia (p = 0.041, p = 0.043 respectively). There was a significant difference in venular junctional exponent between high myopia and low to moderate myopia (p = 0.031).ConclusionThe vascular bifurcation differs in dependence on the myopic refractive error and a significant increase in the difference can be observed in high myopic eyes.

Retinal vascular measures from diabetes retinal screening photographs and risk of incident dementia in type 2 diabetes: A GoDARTS study.

ObjectivePatients with diabetes have an increased risk of dementia. Improved prediction of dementia is an important goal in developing future prevention strategies. Diabetic retinopathy screening (DRS) photographs may be a convenient source of imaging biomarkers of brain health. We therefore investigated the association of retinal vascular measures (RVMs) from DRS photographs in patients with type 2 diabetes with dementia risk.Research Design and MethodsRVMs were obtained from 6,111 patients in the GoDARTS bioresource (635 incident cases) using VAMPIRE software. Their association, independent of Apo E4 genotype and clinical parameters, was determined for incident all cause dementia (ACD) and separately Alzheimer's disease (AD) and vascular dementia (VD). We used Cox’s proportional hazards with competing risk of death without dementia. The potential value of RVMs to increase the accuracy of risk prediction was evaluated.ResultsIncreased retinal arteriolar fractal dimension associated with increased risk of ACD (csHR 1.17; 1.08–1.26) and AD (HR 1.33; 1.16–1.52), whereas increased venular fractal dimension (FDV) was associated with reduced risk of AD (csHR 0.85; 0.74–0.96). Conversely, FDV was associated with increased risk of VD (csHR 1.22; 1.07–1.40). Wider arteriolar calibre was associated with a reduced risk of ACD (csHR 0.9; 0.83–0.98) and wider venular calibre was associated with a reduced risk of AD (csHR 0.87; 0.78–0.97). Accounting for competing risk did not substantially alter these findings. RVMs significantly increased the accuracy of prediction.ConclusionsConventional DRS photographs could enhance stratifying patients with diabetes at increased risk of dementia facilitating the development of future prevention strategies.

Acute effects of caffeine and glucose intake on retinal vessel calibres in healthy volunteers

PurposeTo evaluate the acute effects of caffeine and glucose intake on retinal vascular calibre of healthy adults.MethodsThis prospective crossover study was conducted at the Centre for Eye Research Australia (Melbourne, Australia). Standardized doses of 300 mg caffeine (approximately 3 cups coffee), 30 g glucose or 300 ml of water, were each given to 19 healthy subjects on separate days. Retinal photographs and blood pressure measurements were taken at baseline, 30-, 60- and 120-min after ingestion of each solution. Central retinal artery and vein equivalents (CRAE, CRVE) and the arterio-venule ratio were measured using computer-assisted software. The mean retinal vascular calibre measurements were compared between pre- and post-ingestion images.ResultsAfter caffeine intake, significant reductions were observed in mean CRAE of − 9.3 μm, − 10.4 μm and − 8.5 μm and CRVE of − 16.9 μm, − 18.7 μm and − 16.1 μm at 30-, 60- and 120-min after intake when compared with baseline (p ≤ 0.002 for all; paired t test). No significant changes were observed in mean retinal vascular calibre measurements after intake of either glucose or water when compared to baseline (p ≥ 0.072 for all). When controlling for baseline characteristics and blood pressure measurements, only caffeine intake had a significant effect on reducing both CRAE and CRVE at all time points post ingestion (p ≤ 0.003 for all, multiple linear regression model).ConclusionCaffeine is associated with an acute vasoconstrictive effect on retinal arterioles and venules in healthy subjects. Factors other than blood pressure-induced autoregulation play a significant role in caffeine-associated retinal vasoconstriction.

Association between retinal vascular measures and brain white matter lesions in schizophrenia.

Recent studies have examined retinal vascular abnormalities in schizophrenia as retinal vascular imaging is a non-invasive proxy to cerebral microvasculature. However, relation between retinal vascular abnormalities and brain structure is not well examined in schizophrenia. Hence in this study, for the first time, we examined the relationship between retinal vascular measures and brain white matter lesions in schizophrenia. We examined brain white matter lesions as they are considered a predictive marker for future adverse cerebrovascular event. We acquired retinal vascular images of both eyes using a non-mydriatic camera and calculated retinal vascular diameter, tortuosity, trajectory and fractal dimension using validated methods. All patients underwent Magnetic Resonance Imaging of bran and we computed white matter hypo-intensities using Freesurfer software. We performed a linear regression analysis to examine the relationship between white matter hypo-intensities and retinal vascular measures controlling for age, sex, fasting blood sugar, creatinine, whole-brain volume, and antipsychotic dose. The regression model was significant in Schizophrenia patients (R=0.983;R2=0.966;-F=10.849;p=0.008) but not in healthy volunteers (R=0.828;R2=0.686;F=0.182; p=0.963). Among the retinal vascular measures, arterial tortuosity (β=0.963;p-0.002), tortuosity (β=-1.002;p=0.001) and fractal dimension (β=-0.688;p=0.014) were significant predictors of white matter lesions. The current study's findings support the conclusion that retinal vascular fractal dimension and tortuosity are associated with changes in cerebral white matter and may be considered proxy markers for cerebral microvasculature in schizophrenia. Considering the relationship between white matter lesions and stroke, these observations could have important clinical implications to screen schizophrenia patients for risk of adverse cerebrovascular event.

Comparing Measurements of Vascular Diameter Using Adaptative Optics Imaging and Conventional Fundus Imaging.

The aim of this prospective study was to compare retinal vascular diameter measurements taken from standard fundus images and adaptive optics (AO) images. We analysed retinal images of twenty healthy subjects with 45-degree funduscopic colour photographs (CR-2 Canon fundus camera, Canon™) and adaptive optics (AO) fundus images (rtx1 camera, Imagine Eyes®). Diameters were measured using three software applications: the VAMPIRE (Vessel Assessment and Measurement Platform for Images of the REtina) annotation tool, IVAN (Interactive Vessel ANalyzer) for funduscopic colour photographs, and AO_Detect_Artery™ for AO images. For the arterial diameters, the mean difference between AO_Detect_Artery™ and IVAN was 9.1 µm (−27.4 to 9.2 µm, p = 0.005) and the measurements were significantly correlated (r = 0.79). The mean difference between AO_Detect_Artery™ and VAMPIRE annotation tool was 3.8 µm (−34.4 to 26.8 µm, p = 0.16) and the measurements were poorly correlated (r = 0.12). For the venous diameters, the mean difference between the AO_Detect_Artery™ and IVAN was 3.9 µm (−40.9 to 41.9 µm, p = 0.35) and the measurements were highly correlated (r = 0.83). The mean difference between the AO_Detect_Artery™ and VAMPIRE annotation tool was 0.4 µm (−17.44 to 25.3 µm, p = 0.91) and the correlations were moderate (r = 0.41). We found that the VAMPIRE annotation tool, an entirely manual software, is accurate for the measurement of arterial and venular diameters, but the correlation with AO measurements is poor. On the contrary, IVAN, a semi-automatic software tool, presents slightly greater differences with AO imaging, but the correlation is stronger. Data from arteries should be considered with caution, since IVAN seems to significantly under-estimate arterial diameters.

Association between retinal vascular caliber and brain structure in schizophrenia.

Several lines of research in the last decade have indicated the potential utility of retina as a window to the brain. Emerging evidence suggests abnormalities in retinal vascular caliber in schizophrenia. However, the relationship between retinal vascular measures and brain structure has not been examined in schizophrenia to date. Hence, we examined the relationship between retinal vasculature measured using fundus photography and brain structure measured using magnetic resonance imaging. We recruited 17 healthy volunteers and 20 patients with schizophrenia. Using a non-mydriatic camera, we captured the images for left and right eyes separately and retinal vascular calibers were calculated using a semi-automated software package. Whole-brain anatomical T1 MPRAGE images were acquired using a 3-Tesla MRI scanner. Whole-brain and regional volume and cortical thickness were calculated using the Freesurfer software package. We used FreeSurfer's QDEC interface to compute vertex-by-vertex for analysis of the volume and cortical thickness. The relation between brain volume, cortical thickness, and retinal vascular caliber was examined using partial correlation and regression analysis. There was a significant negative correlation between average CRVE and global cortical mean thickness in schizophrenia but not in healthy. In schizophrenia patients, there was a significant negative correlation between average CRVE and cortical thickness in frontal regions - left rostral middle frontal, left superior frontal, and right caudal middle frontal gyri and posterior brain regions - left lateral occipital gyrus and left posterior cingulate cortex. The findings of the study suggest potential utility of retinal venular diameter as a proxy marker to abnormal neurodevelopment in schizophrenia.

Correlation between retinal vascular parameters and cystatin C in patients with type 2 diabetes.

To investigate the relationship between retinal vascular parameters and cystatin C in patients with type 2 diabetes in northwestern China. This was a cross-sectional study of 1689 patients with type 2 diabetes. A validated fully automated computer program was used to extract retinal vascular parameters from the entire vascular tree. Multiple logistic regression analyses were conducted to investigate the relationship between these vascular measurements and cystatin C. For retinal vascular geometrical measurements, smaller arteriolar fractal dimension was related to high cystatin C after adjusting for multiple variables (odds ratio [OR] 0.149, 95% CI 0.042-0.532). For retinal vascular caliber measurements, narrower central and middle arteriolar calibers were related to high cystatin C after adjusting for multiple variables (central: OR 0.922, 95% CI 0.886-0.960; middle: OR 0.940, 95% CI 0.901-0.981). Wider central, middle and peripheral venular calibers were associated with high cystatin C after adjusting for multiple variables (central: OR 1.058, 95% CI 1.003-1.117; middle: OR 1.094, 95% CI 1.040-1.150; peripheral: OR 1.075, 95% CI 1.023-1.130). Multiple retinal vascular geometrical and caliber measurements are associated with cystatin C in type 2 diabetic patients. Further studies are needed to explore whether these retinal vascular changes can predict the incidence and progress of diabetic nephropathy.

Albuminuria and retinal vessel density in diabetes without diabetic retinopathy: the Kailuan Eye Study.

Diabetic retinopathy and chronic kidney disease are both major complications of diabetes mellitus. We explored the relationship between retinal vessel density (VD) and albuminuria in diabetic patients without conventionally defined diabetic retinopathy. The cross-sectional community-based Kailuan Diabetic Retinopathy Study included patients with type 2 diabetes without diabetic retinopathy who participated in the community-based longitudinal Kailuan study and who had undergone ocular fundus photography, kidney function assessment, and optical coherence tomographic angiography (OCT-angiography) for the assessment the retinal perfusion density (PD) and retinal VD. The study included 447 patients (mean age: 60.9±9.7years). Higher PD and VD were associated with a lower urinary albumin-creatinine ratio (uACR) (macular region: p=0.007: standardized regression coefficient beta: -0.14; and p=0.008, beta: -0.13, respectively; parafoveal region: p=0.006, beta: -0.14; and p=0.007, beta: -0.14, respectively) after adjusting for age and ocular axial length. In a reverse manner, higher uACR was associated with lower PD and VD (macular region: p=0.009, beta: -0.14; and p=0.01, beta: -0.14, respectively; parafoveal region: p=0.008, beta: -0.14; and p=0.01, beta: -0.14, respectively), after adjusting for diabetes duration, blood pressure, serum concentration of C-reactive protein and high-density lipoprotein cholesterol and ocular axial length. In a multivariable model, the prevalence of macroalbuminuria increased by 11% (95% CI: 2%, 18%) and 17% (95% CI: 3%, 30%), respectively, for each mm-1 decrease in VD and each unit decrease in PD. After adjusting for systemic and ocular parameters, diabetic patients without diabetic retinopathy showed a reduction in OCT-angiographic retinal vascular measurements in association with systemic parameters indicating chronic kidney disease. Optical coherence tomographic (OCT)-angiographic retinal microvascular parameters may serve as markers for chronic kidney disease.

Longitudinal assessment of quantitative ultra-widefield ischaemic and vascular parameters in sickle cell retinopathy

PurposeTo evaluate longitudinal quantitative ischaemic and vasculature parameters, including ischaemic index, vessel area, length and geodesic distance in sickle cell retinopathy (SCR) on ultra-widefield fluorescein angiography (UWFA).MethodsOptimal UWFA images from...

Correlations among peripapillary vasculature, macular superficial capillaries, and eye structure in healthy and myopic eyes of Chinese young adults (STROBE).

The correlations between retinal vessel distribution, anterior chamber depth (ACD) and other myopic eye structural parameters remains elusive. This study aims to investigate retinal vasculature and eye structure correlations in healthy and myopic eyes of Chinese young adults.In this cross-sectional study, 181 eyes (97 adults) were recruited. Macular and peripapillary vasculature was quantified by optical coherence tomography angiography. Correlations between retinal vasculature and eye structure were analyzed using multivariable linear regression.There were significant differences in ACD, spherical equivalent, axial length (AL), superficial macular vascular density (MVD), peripapillary vascular density (PVD) and circumference of foveal avascular zone (FAZ) among emmetropia, low-myopia, moderate-myopia, and high-myopia groups (both P < 0.05). Furthermore, ACD had significant positive correlation with AL and FAZ, but negative correlation with PVD. MVD also had a negative correlation with AL (beta = –0.247, P < .001). In addition, there was a significant negative correlation between circumference of the FAZ and spherical equivalent as well as central subfield thickness (beta = –0.20, P = .005; beta = –0.334, P < .001, respectively).The degree of myopia affected ACD, MVD, PVD, and circumference of the FAZ in eyes of young healthy adults. Meanwhile, ACD has a positive, while retinal vascular system measurements have a negative correlation with increasing severity of myopia.