Ocular Blood Flow Velocity Determined by Color Doppler Imaging in Diabetic Retinopathy

The retinal oxygen metabolism and hemodynamics as a substitute for biochemical tests to predict nonproliferative diabetic retinopathy

Predicting the occurrence of nonproliferative diabetic retinopathy (NPDR) using biochemical parameters is invasive, which limits large-scale clinical application. Noninvasive retinal oxygen metabolism and hemodynamics of 215 eyes from 73 age-matched healthy subjects, 90 diabetic patients without DR, 40 NPDR, and 12 DR with postpanretinal photocoagulation were measured with a custom-built multimodal retinal imaging device. Diabetic patients underwent biochemical examinations. Two logistic regression models were developed to predict NPDR using retinal and biochemical metrics, respectively. The predictive model 1 using retinal metrics incorporated male gender, insulin treatment condition, diastolic duration, resistance index, and oxygen extraction fraction presented a similar predictive power with model 2 using biochemical metrics incorporated diabetic duration, diastolic blood pressure, and glycated hemoglobin A1c (area under curve: 0.73 vs. 0.70; sensitivity: 76% vs. 68%; specificity: 64% vs. 62%). These results suggest that retinal oxygen metabolic and hemodynamic biomarkers may replace biochemical parameters to predict the occurrence of NPDR .

Quantitative evaluation of ocular vascularity and correlation analysis in patients with diabetic retinopathy by SMI and OCTA

AIMS

To find potential relation between retrobulbar vessels and fundus microvessels and to detect sensitive and effective clinical indicators in predicting the progress of diabetic retinopathy (DR), ocular hemodynamics were measured using superb microvascular imaging (SMI) and ultrawide-field optical coherence tomography angiography (UWF-OCTA).

METHODS

Observational, cross-sectional study evaluating ocular hemodynamics in patients with DR by SMI (Aplio i900, Canon Medical) and UWF-OCTA (BM-400 K BMizar, Tupai Medical Technology). The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) of the central retinal artery (CRA), posterior ciliary artery (PCA), and ophthalmic artery (OA) were measured by SMI. UWF-OCTA evaluated the fundus vascular parameters. A correlation analysis was used to determine the correlation between SMI and UWF-OCTA parameters.

RESULTS

One hundred thirty-nine eyes of 139 diabetic patients were included: 29 without DR (NDR), 36 with mild to moderate nonproliferative DR (M-NPDR), 37 with severe NPDR (S-NPDR), and 37 with proliferative DR (PDR). PSV and EDV of retrobulbar vessels decreased from NDR to S-NPDR while increasing PDR. RI of OA showed a decreasing trend in the progression of DR, but other vessels didn't show the same trend. ROC curve analysis showed that CRAPSV, CRAEDV, PCAEDV, OAPSV, and OAEDV had diagnostic value distinguishing M-NPDR and S-NPDR. The correlation analysis observed a significant association between the SMI parameters of CRA and PCA and UWF-OCTA parameters. CRA hemodynamics were more associated with fundus vascular parameters, especially the retina, in the NDR group than in the M-NPDR group. In contrast, PCA consistently correlated with fundus vascular parameters, especially in the choroid, from the NDR to the M-NPDR group. However, OA showed a poor correlation with OCTA parameters.

CONCLUSION

The velocity of retrobulbar vessels, mainly the CRA, may serve as a valuable predictor for assessing the progress of DR. The use of SMI in diabetic patients may help identify patients at risk of developing retinopathy.

Doppler ultrasound-based evaluation of hemodynamic changes in the ophthalmic artery and central retinal artery in patients with type 1 diabetes mellitus without retinopathy and with mild non-proliferative retinopathy

Aim

Determination of blood flow parameters in the ophthalmic artery and central retinal artery using Doppler ultrasound in patients with type 1 diabetes mellitus without fundus signs of diabetic retinopathy and with mild non-proliferative retinopathy.

Material and methods

To eliminate the impact of other systemic factors on vascular flow, the study enrolled a total of 80 patients with type 1 diabetes mellitus, aged between 18 and 45 years. The study participants did not have any diabetic complications or other systemic or ocular comorbidities. The control group comprised 81 healthy individuals within a similar age range. Color Doppler ultrasound examinations of the ophthalmic artery and central retinal artery were performed to evaluate selected blood flow parameters including peak systolic velocity, end-diastolic velocity, and resistance index.

Results

Patients with type 1 diabetes mellitus exhibited statistically significant decrease in both systolic and end-diastolic velocities in the central retinal artery, accompanied by an elevation in resistance index, compared to the control group. The study revealed differences in blood flow parameters between the patients without fundus changes and those exhibiting mild non-proliferative retinopathy. Specifically, patients with retinopathy showed a significant decrease in both systolic velocity and end-diastolic velocity in the central retinal artery. No differences were observed for the same parameters in the ophthalmic artery. When analyzing the patients' blood flow parameters in relation to the degree of diabetes control, as determined by glycated hemoglobin levels, a statistically significant reduction in systolic velocity was identified in both the ophthalmic and central retinal arteries in the group with poorly controlled diabetes.

Conclusions

Examination of the orbital vessels using Doppler ultrasound in patients with type 1 diabetes mellitus holds promise as an effective method for early detection of vascular abnormalities.

Evaluation of Hemodynamic Changes in Retrobulbar Blood Vessels Using Color Doppler Imaging in Diabetic Patients

Background—Diabetic retinopathy is a common complication of long-standing hyperglycemia. Microangiopathy-induced retinal changes are well-visualized on ophthalmoscopic examination. However, certain hemodynamic alterations have also been documented in the diabetic population, which have not been completely understood. Aim—To study the hemodynamic changes in retrobulbar circulation in diabetic patients with and without retinopathy, and to compare these changes with non-diabetic controls. Materials and Methods—This hospital-based prospective study included 50 diabetic and 50 non-diabetic patients. The diabetic groups consisted of 25 patients without retinopathy and 25 patients with retinopathy, and were labeled as Groups I and II, respectively. All subjects underwent orbital color Doppler ultrasonography using a linear high-frequency probe. The color Doppler parameters (peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI)) were measured and recorded using the spectral waveform of the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCA). Comparison of obtained values was carried out using appropriate tests of significance. Results—The resistive indices of the ophthalmic, central retinal, and short posterior ciliary arteries were significantly higher in diabetic patients compared to controls (p < 0.001). The difference was also significant between Group I and Group II. Comparison of PSV and EDV of CRA and SPCAs among three groups using one-way ANOVA revealed a significant difference, with the highest blood flow velocities in the control group and the lowest in diabetics with retinopathy. The ophthalmic artery showed no significant change in blood flow velocity. Analysis using the Pearson correlation coefficient provided a positive correlation between the RI values of OA, CRA, and SPCA and the presence of diabetic retinopathy (OA = r 0.417, p < 0.001; CRA = r 0.466, p < 0.001; SPCA = r 0.438; p < 0.001). Conclusions—The resistive index of OA, CRA, and SPCA is a reliable indicator to assess diabetic-associated hemodynamic changes. The use of orbital color Doppler ultrasonography in diabetic patients can help in the identification of patients who are at risk of developing retinopathy.

Evaluation of retrobulbar circulation in type 2 diabetic patients using color Doppler imaging

Purpose:

To investigate the retrobulbar circulatory parameters in type 2 diabetes mellitus patients with color Doppler imaging (CDI) and compare the results with nondiabetic controls.

Methods:

This prospective study included 50 type 2 diabetic patients and 50 age-matched controls. Seven field stereo fundus photography was used to diagnose and classify diabetic retinopathy (DR). Diabetic patients were further divided into two: Group 1, consisted of patients with no DR, mild and moderate non-proliferative DR (n = 36); Group 2, severe nonproliferative and proliferative DR (n = 14). CDI was performed using Philips iU22 xMATRIX ultrasound. The peak systolic velocity (PSV), end-diastolic velocity (EDV), resistivity index (RI) and pulsatile index (PI) of ophthalmic (OA), posterior ciliary artery (PCA), and central retinal artery (CRA) along with central retinal vein (CRV) were recorded.

Results:

RI in the ophthalmic artery was significantly higher in both DR groups than the control group (P = 0.000). Diabetic Group 1 had decreased blood flow velocity (PSV and EDV) in PCA compared to controls (P = 0.046 and P = 0.010, respectively). Group 2 DR had significantly reduced EDV and increased RI in CRA compared to Group 1 (P = 0.015). Binary logistic regression analysis revealed glycosylated hemoglobin and RI of OA to be independent risk factors of DR.

Conclusion:

Significant changes in resistivity index and flow velocities were observed in the retrobulbar vessels, especially in ophthalmic artery in diabetics compared to controls. CDI with results of increased resistance or decreased flow could be useful to predict individuals at higher risk for developing severe DR.

Doppler Indices of the Ophthalmic Artery in Pregnant Women With Pregestational Diabetes Mellitus With and Without Retinopathy

OBJECTIVES

To evaluate ophthalmic Doppler velocimetry patterns in pregnant women with pregestational diabetes mellitus with and without retinopathy in comparison to pregnant women without gestational intercurrences.

METHODS

This cross-sectional observational study analyzed Doppler indices of the ophthalmic arteries, including the resistive index (RI), pulsatility index, peak systolic velocity, second peak systolic velocity, peak ratio, and end-diastolic velocity (EDV), in 3 groups of pregnant women: diabetic with retinopathy (n = 12); diabetic without retinopathy (n = 85); and nondiabetic controls (n = 122). The Kruskal-Wallis test was used for the statistical analysis with a probability of 95%.

RESULTS

The mean gestational ages ± SDs of pregnant women with and without retinopathy and nondiabetic controls were 29.1 ± 2.2, 29.7 ± 2.7, and 31 ± 1.0 weeks, respectively, with no significant differences between the groups (P > .099). The mean RI in the group with retinopathy was significantly higher (P = .030) than in the control group, but it did not significantly differ compared to the group without retinopathy (P = .204). The RI in the control group did not differ from that in the group without retinopathy (P = .079). The EDV was significantly lower in the group with retinopathy (P = .015) in relation to the control group, but there were no differences compared to the group without retinopathy (P = .217).

CONCLUSIONS

Pregnant women with pregestational diabetes mellitus and retinopathy had increased vascular impedance in the ophthalmic artery together with a reduction in the EDV, which was probably related to ischemia, thrombosis, and neovascularization of retinal vessels.

Evaluation of Resistive Index of Orbital Vessels Using Color Doppler Imaging in Patients with Type 2 Diabetes Mellitus

Background

Resistive index (RI), derived from color Doppler imaging (CDI), is a marker of vascular resistance used widely in varied clinical settings. The aim of this study was to analyze the association between RIs of the orbital vessels in a pure cohort of type 2 diabetic patients with or without retinopathy using CDI.

Methods

Fifty patients having type 2 diabetes and 50 age-matched controls were evaluated in this prospective study. Diabetic retinopathy (DR) was diagnosed based on seven-field stereo fundus photography and diabetic patients were divided into two. Patients with no DR (n = 26) were taken as Group 1, while patients with DR (n = 24) were taken as Group 2. CDI was performed and the RIs of the ophthalmic artery (OA), posterior ciliary artery (PCA), central retinal artery (CRA), and central retinal vein (CRV) were measured.

Results

Significant differences were observed in the mean RI values of all orbital arteries between controls and patients with DR (P < 0.05). Comparison of RI values between controls and Group 1 showed no significant differences. Mean RI values of the PCA and CRA were found to be significantly higher in the patients in Group 2 than in Group 1 (P = 0.03 and P < 0.001, respectively). The duration of diabetes correlated with the mean RI of all the orbital vessels. RI of the CRA was a reliable predictive indicator for DR (P = 0.001).

Conclusion

RIs of the orbital arteries are significantly higher in patients with DR. RI of the orbital vessels can be a potentially useful biomarker in the early diagnosis and follow-up of patients with DR.

Ocular microcirculation changes, measured with laser speckle flowgraphy and optical coherence tomography angiography, in branch retinal vein occlusion with macular edema treated by ranibizumab

PURPOSE

This study searched for early predictive vascular biomarkers for visual outcomes in eyes with macular edema caused by branch retinal vein occlusion (BRVOME).

METHODS

Twenty-four eyes of 24 subjects with BRVOME were treated with the intravitreal injection of ranibizumab (IVR) for at least 6 months. We measured mean blur rate (MBR) in the optic nerve head (ONH) and vessel density (VD) in the macula with laser speckle flowgraphy and optical coherence tomography angiography, respectively.

RESULTS

Six-month post-IVR best-corrected visual acuity (BCVA) was correlated positively with age, pre-IVR BCVA, 1-month post-IVR BCVA, 3-month post-IVR BCVA and pre-IVR systolic blood pressure (P < 0.001, P < 0.001, P < 0.001, P < 0.001 and P = 0.02, respectively) and negatively with pre-IVR overall MBR, 1-month post-IVR overall MBR, 6-month post-IVR overall MBR, 3-month post-IVR deep retinal capillary plexus (DCP) VD and 6-month post-IVR DCP VD (P = 0.03, P = 0.03, P = 0.02, P = 0.01 and P = 0.005, respectively). Furthermore, a multiple regression analysis showed that pre-IVR overall MBR (β =  - 0.67, P = 0.009) was among independent prognostic factors predicting 6-month post-IVR BCVA. Six-month post-IVR DCP VD was also correlated with overall MBR at all time points.

CONCLUSION

ONH blood flow may be a pre-IVR biomarker of both visual outcomes and post-IVR deep macular microcirculation in eyes with BRVOME.

Level of hormones in menopause in relation to diabetic retinopathy among type 2 diabetic women

Hormonal transition among middle-aged women with type 2 diabetes may exert an impact in the development of diabetic retinopathy (DR). In this cross-sectional study, we aimed to assess the levels of estradiol, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in the presence of DR and their relationship with risk factors for DR among pre- and post-menopausal women with type 2 diabetes. Serum levels of estradiol, FSH, and LH were measured using the immunoassay technique. All statistical analysis was performed using SPSS software. From the 255 participants, diabetes duration-matched, 35 premenopausal, and 57 postmenopausal women were selected for analysis. The levels of estradiol, LH, and FSH were found to be similar in participants with and without DR among pre- and post-menopausal women with diabetes. Estradiol level was not found to be related with the risk factors of DR among women with type 2 diabetes. In conclusion, female sex hormone, estradiol is not related to the presence of DR. Further prospective studies are necessary to reveal the mechanistic role of this hormone in the development of DR.

Resistive index of central retinal artery is a bioimaging biomarker for severity of diabetic retinopathy

BACKGROUND

The present study was undertaken to assess the resistive index (RI) of central retinal artery (CRA) as a bioimaging biomarker for the severity of diabetic retinopathy (DR), for the first time.

METHODS

Eighty-one consecutive patients of type 2 diabetes mellitus between the ages of 40 and 70 years were included in a tertiary care center-based cross sectional study. Severity of retinopathy was assessed according to Early Treatment Diabetic Retinopathy Study (ETDRS) classification: diabetes mellitus with no retinopathy (No DR) (n = 26); non-proliferative diabetic retinopathy (NPDR) (n = 29); and proliferative diabetic retinopathy (PDR) (n = 26). Twenty-six healthy controls of similar age were also included. Resistive index of CRA was studied using color Doppler and gray scale sonography. Central subfield thickness (CST), cube average thickness (CAT), retinal photoreceptor ellipsoid zone (EZ) disruption, and retinal nerve fiber layer (RNFL) thickness were evaluated using spectral domain optical coherence tomography. Sensitivity and specificity were assessed by receiver operating characteristic (ROC) curve.

RESULTS

Mean RI of CRA for the study groups revealed significant increase with severity of diabetic retinopathy (F = 10.24, P < 0.001). The ROC curve analysis showed diagnostic accuracy of RI of CRA (area under curve = 0.841-0.999; sensitivity = 76-100%, specificity = 95.45-100%, P < 0.001) in discriminating controls and patients. Univariate regression analysis revealed significant association between the study groups and RI of CRA (P < 0.001). RI of CRA correlated positively with CST (r = 0.37), CAT (r = 0.45), EZ disruption (r = 0.43) and negatively with RNFL thickness (r = - 0.35) (P < 0.001).

CONCLUSIONS

Resistive index of CRA is a reliable bioimaging biomarker for the severity of DR.

ASSESSMENT OF RETINAL BLOOD FLOW IN DIABETIC RETINOPATHY USING DOPPLER FOURIER-DOMAIN OPTICAL COHERENCE TOMOGRAPHY

PURPOSE

To evaluate retinal blood flow measurements in normal eyes and eyes with varying levels of diabetic retinopathy (DR) using Doppler Fourier-domain optical coherence tomography (FD-OCT).

METHODS

Twenty-two eyes of 19 subjects, 10 with severe nonproliferative DR (NPDR) and 12 with proliferative DR (PDR), were compared with 44 eyes of 40 healthy control subjects. All eyes were scanned by RTvue FD-OCT. Color disk photographs and cube/volume scans of the optic nerve head were obtained. Doppler OCT scans and accessory imaging data were imported into Doppler OCT of Retinal Circulation grading software to calculate TRBF and vascular parameters (e.g., venous and arterial cross-sectional area). Measurements were compared between cases and controls using independent t-tests.

RESULTS

Mean TRBF was 44.98 ± 9.80 (range: 30.18-64.58) µL/minute for normal eyes, 35.80 ± 10.48 (range: 20.69-49.56) µL/minute for eyes with severe NPDR, and 34.79 ± 10.61 (range: 16.77-48.9) µL/minute for eyes with PDR. Mean TRBF was significantly lower in eyes with severe NPDR (P = 0.01) and PDR (P = 0.003) than in normal eyes.

CONCLUSION

Total retinal blood flow was significantly lower in eyes with severe NPDR and PDR compared with normal eyes. Retinal blood flow determined by Doppler OCT may be a useful parameter for evaluating patients with DR.

Gonadal Hormones and Retinal Disorders: A Review

AIM

Gonadal hormones are essential for reproductive function, but can act on neural and other organ systems, and are probably the cause of the large majority of known sex differences in function and disease. The aim of this review is to provide evidence for this hypothesis in relation to eye disorders and to retinopathies in particular.

METHODS

Epidemiological studies and research articles were reviewed.

RESULTS

Analysis of the biological basis for a relationship between eye diseases and hormones showed that estrogen, androgen, and progesterone receptors are present throughout the eye and that these steroids are locally produced in ocular tissues. Sex hormones can have a neuroprotective action on the retina and modulate ocular blood flow. There are differences between the male and the female retina; moreover, sex hormones can influence the development (or not) of certain disorders. For example, exposure to endogenous estrogens, depending on age at menarche and menopause and number of pregnancies, and exposure to exogenous estrogens, as in hormone replacement therapy and use of oral contraceptives, appear to protect against age-related macular degeneration (both drusenoid and neurovascular types), whereas exogenous testosterone therapy is a risk factor for central serous chorioretinopathy. Macular hole is more common among women than men, particularly in postmenopausal women probably owing to the sudden drop in estrogen production in later middle age. Progestin therapy appears to ameliorate the course of retinitis pigmentosa. Diabetic retinopathy, a complication of diabetes, may be more common among men than women.

CONCLUSION

We observed a correlation between many retinopathies and sex, probably as a result of the protective effect some gonadal hormones may exert against the development of certain disorders. This may have ramifications for the use of hormone therapy in the treatment of eye disease and of retinal disorders in particular.

In vivo imaging of retinal hemodynamics with OCT angiography and Doppler OCT

Retinal hemodynamics is important for early diagnosis and precise monitoring in retinal vascular diseases. We propose a novel method for measuring absolute retinal blood flow in vivo using the combined techniques of optical coherence tomography (OCT) angiography and Doppler OCT. Doppler values can be corrected by Doppler angles extracted from OCT angiography images. A three-dimensional (3D) segmentation algorithm based on dynamic programming was developed to extract the 3D boundaries of optic disc vessels, and Doppler angles were calculated from 3D vessel geometry. The accuracy of blood flow from the Doppler OCT was validated using a flow phantom. The feasibility of the method was tested on a subject in vivo. The pulsatile retinal blood flow and the parameters for retinal hemodynamics were successfully obtained.

Can we measure the spiral and uterine artery blood flow by real-time sonography and Doppler indices to predict spontaneous miscarriage in a normal-risk population?

Introduction: The predictive value of spiral artery flow Doppler measurements of a subsequent early miscarriage in first trimester pregnancy is explored here. Objective: The aim of this study is to determine uterine and spiral artery blood flow changes in first trimester subsequent miscarriages and correlate within the mechanisms of the Doppler indicies. Study design: The uterine artery and spiral artery pulsatility and resistance indexes, systolic and diastolic ratios, acceleration times, and blood flow of both the right and left uterine arteries were obtained by trans vaginal color Doppler ultrasonography in consecutive viable pregnancies between 5 and 12 gestational week. Women were subsequently classified as having continuing pregnancies or pregnancy loss before 20 weeks gestation. To predict subsequent pregnancy loss, Doppler findings were adjusted for maternal age, history of previous abortion, presence of subchorionic hematoma, embryonic bradycardia, and gestational age by means of multivariate logistic regression analysis. The cut-off values are used for the ROC curve. Results: Twenty-five pregnancies (11.7%) were spontaneously aborted before 20 weeks of gestational age. In 29 (13.6%) cases there were previously abortion history, 30 (14%) had bradycardia, and 37 (17.3%) had subchoronic hematoma. Regarding the parameters of uterine and spiral artery pulsatility and resistive index, acceleration time, systolic/diastolic ratios and blood flows, only uterine artery S/D low values were significantly associated with pregnancy loss in the multivariate logistic regression analysis (P = 0.0001,95% CI: 4.968-55.675). Conclusion: The uterine artery systolic/diastolic ratios have a predictive value for early pregnancy loss and seem to be useful as a marker. On the other hand, spiral artery changes could be so local that they cannot be determined by the parameters of spectral Doppler techniques. This suggests that uterine vascular bed alterations should be measured to understand the prognosis of early pregnancy loss during the first trimester.

Strain-blood pressure index for evaluation of early changes in elasticity of anterior tibial artery in patients with type 2 diabetes mellitus

Background

The aim of this study was to investigate the feasibility and value of strain-blood pressure index (SBPI) to assess early changes in elasticity of anterior tibial artery in patients with type 2 diabetes mellitus (T2DM).

Material/Methods

Eighty-one randomly selected in-patients with T2DM were divided into 2 groups – a vascular complication negative group (n=42) and a vascular complication positive group (n=39). Forty healthy volunteers were enrolled in a control group. Ultrasonographic scans using Xstrain™ technique were conducted for every patient to obtain the maximum circumferential strain (CSmax) of anterior tibial artery; patient blood pressure was also measured for calculating strain-blood pressure index (SBPI=CS_max/[(local pulse pressure)/local diastolic blood pressure] ×100%. Afterwards, SBPIs of various groups were comparatively analyzed.

Results

Differences in SBPIs among the 3 groups were statistically significant (control group > negative group > positive group, P<0.05).

Conclusions

SBPI could be used as a new indicator for the evaluation on the anterior tibial arterial elasticity of T2DM patients and it was able to reflect the early elasticity changes in anterior tibial arteries in T2DM patients with atherosclerosis.

Retrobulbar blood flow changes in eyes with diabetic retinopathy: a 10-year follow-up study

Purpose

We sought to assess long-term changes in the flow parameters of retrobulbar vessels in diabetic patients.

Methods

The retrobulbar circulation of 138 eyes was evaluated between 1994 and 1995 and 36 eyes were reevaluated between 2004 and 2008 (study group). They were divided into four groups: eyes of diabetic patients without diabetic retinopathy (DR), eyes with nonproliferative DR, eyes with proliferative DR, and eyes of nondiabetic patients (controls). Color Doppler imaging was used to assess the flow velocities in the major retrobulbar vessels. The resistive index (RI) was calculated and compared among the groups and between the two time periods.

Results

RI values of the central retinal artery and posterior ciliary artery had increased in the two non-DR groups and in the nonproliferative DR group, with a surprising decrease measured in eyes with proliferative DR (P= nonsignificant [NS]). Combining the nonproliferative DR and proliferative DR groups resulted in a milder increase of the RI of the posterior ciliary artery (P= NS) and the central retinal artery (P=0.02) in the DR group compared to the other groups.

Conclusion

Our results demonstrate that an increase of the resistance in the retrobulbar vessels, as a part of DR, can lessen over time and may even be reversed.

Color Doppler Imaging Analysis of Retrobulbar Blood Flow Velocities in Diabetic Patients Without or With Retinopathy: A Meta-analysis

OBJECTIVES

To analyze hemodynamic changes in retrobulbar blood vessels using color Doppler imaging in diabetic patients without or with retinopathy.

METHODS

Pertinent publications were retrieved from 3 databases. Changes in peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) of the ophthalmic artery, central retinal artery, and short posterior ciliary artery of diabetic eyes without or with retinopathy and healthy controls were evaluated by color Doppler imaging. Comparisons were conducted in 3 groups: group 1, no retinopathy versus control; group 2, retinopathy versus control; and group 3, no retinopathy versus retinopathy.

RESULTS

In group 1, eyes without retinopathy had a significant increase in ophthalmic artery PSV (P = .002), with no heterogeneity (Pheterogeneity = 0.09; inconsistency index [I(2)] = 46%); however, significant reductions in central renal artery PSV and EDV were shown (P = .002; P = .007, respectively), with significant heterogeneity (Pheterogeneity < .00001; I(2) = 85%; Pheterogeneity = .008, I(2) = 68%). A significant increase in ophthalmic artery RI (P = .02) was found in eyes without retinopathy, with heterogeneity (Pheterogeneity = .0009; I(2) = 74%). In group 2, central retinal artery PSV and EDV in eyes with retinopathy decreased significantly (P < 0.00001). Similar results were found for ophthalmic and short posterior ciliary artery EDVs (P= .0003; P< .00001). Ophthalmic artery RI was significantly higher in eyes with retinopathy than controls (P = .0008), with heterogeneity (Pheterogeneity < .00001; I(2) = 84%). In group 3, ophthalmic artery PSV was lower in eyes with retinopathy (P= .04) than eyes without, and central retinal artery PSV and EDV decreased significantly (P = .004; P < .00001) in eyes with retinopathy compared to eyes without. Differences in ophthalmic and central retinal artery RIs were also found in eyes with retinopathy (P = .05; P < .00001).

CONCLUSIONS

Significant changes in retrobulbar blood flow were found in eyes without and with diabetic retinopathy, especially those with retinopathy.

The effect of intravitreal bevacizumab on ocular blood flow in diabetic retinopathy and branch retinal vein occlusion as measured by laser speckle flowgraphy

Background

This study evaluated the effect of intravitreal injection of bevacizumab (IVB) on macular edema associated with diabetic retinopathy (DME) or branch retinal vein occlusion (BRVOME) using laser speckle flowgraphy.

Methods

A comparative interventional study of 25 eyes from 22 patients with macular edema (DME group: 12 eyes; BRVOME group: 13 eyes) who underwent IVB. Mean blur rate (MBR) was measured in the retinal artery, retinal vein, optic nerve head (ONH), and choroid before and after IVB.

Results

In the BRVOME group, there was no significant change in MBR in the retinal artery, retinal vein or ONH, but choroidal MBR decreased significantly (P=0.04). In the DME group, the MBR in the retinal artery, retinal vein, ONH, and choroid decreased significantly (P=0.02, P=0.04, P<0.001, and P=0.04, respectively). In the DME group, pre-IVB MBR in the ONH was significantly correlated with post-IVB foveal thickness (R= −0.71, P=0.002). There was no such correlation in the BRVOME group in the ONH.

Conclusion

IVB had a suppressive effect on circulation in eyes with DME but not in those with BRVOME. This suggests that this noninvasive and objective biomarker may be a useful part of pre-IVB evaluations and decision-making in DME.

Gender differences in ocular blood flow

Gender medicine has been a major focus of research in recent years. The present review focuses on gender differences in the epidemiology of the most frequent ocular diseases that have been found to be associated with impaired ocular blood flow, such as age-related macular degeneration, glaucoma and diabetic retinopathy. Data have accumulated indicating that hormones have an important role in these diseases, since there are major differences in the prevalence and incidence between men and pre- and post-menopausal women. Whether this is related to vascular factors is, however, not entirely clear. Interestingly, the current knowledge about differences in ocular vascular parameters between men and women is sparse. Although little data is available, estrogen, progesterone and testosterone are most likely important regulators of blood flow in the retina and choroid, because they are key regulators of vascular tone in other organs. Estrogen seems to play a protective role since it decreases vascular resistance in large ocular vessels. Some studies indicate that hormone therapy is beneficial for ocular vascular disease in post-menopausal women. This evidence is, however, not sufficient to give any recommendation. Generally, remarkably few data are available on the role of sex hormones on ocular blood flow regulation, a topic that requires more attention in the future.

Color Doppler imaging of the retrobulbar vessels in diabetic retinopathy

Diabetes is a metabolic disease characterized by elevated blood glucose level due to impaired insulin secretion and activity. Chronic hyperglycemia leads to functional disorders of numerous organs and to their damage. Vascular lesions belong to the most common late complications of diabetes. Microangiopathic lesions can be found in the eyeball, kidneys and nervous system. Macroangiopathy is associated with coronary and peripheral vessels. Diabetic retinopathy is the most common microangiopathic complication characterized by closure of slight retinal blood vessels and their permeability. Despite intensive research, the pathomechanism that leads to the development and progression of diabetic retinopathy is not fully understood. The examinations used in assessing diabetic retinopathy usually involve imaging of the vessels in the eyeball and the retina. Therefore, the examinations include: fluorescein angiography, optical coherence tomography of the retina, B-mode ultrasound imaging, perimetry and digital retinal photography. There are many papers that discuss the correlations between retrobulbar circulation alterations and progression of diabetic retinopathy based on Doppler sonography. Color Doppler imaging is a non-invasive method enabling measurements of blood flow velocities in small vessels of the eyeball. The most frequently assessed vessels include: the ophthalmic artery, which is the first branch of the internal carotid artery, as well as the central retinal vein and artery, and the posterior ciliary arteries. The analysis of hemodynamic alterations in the retrobulbar vessels may deliver important information concerning circulation in diabetes and help to answer the question whether there is a relation between the progression of diabetic retinopathy and the changes observed in blood flow in the vessels of the eyeball. This paper presents the overview of literature regarding studies on blood flow in the vessels of the eyeball in patients with diabetic retinopathy.

Quantitative imaging biomarkers for the evaluation of cardiovascular complications in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a prevalent condition in aged populations. Cardiovascular diseases are leading causes of death and disability in patients with T2DM. Traditional strategies for controlling the cardiovascular complications of diabetes primarily target a cluster of well-defined risk factors, such as hyperglycemia, lipid disorders and hypertension. However, there is controversy over some recent clinical trials aimed at evaluating efficacy of intensive treatments for T2DM. As a powerful tool for quantitative cardiovascular risk estimation, multi-disciplinary cardiovascular imaging have been applied to detect and quantify morphological and functional abnormalities in the cardiovascular system. Quantitative imaging biomarkers acquired with advanced imaging procedures are expected to provide new insights to stratify absolute cardiovascular risks and reduce the overall costs of health care for people with T2DM by facilitating the selection of optimal therapies. This review discusses principles of state-of-the-art cardiovascular imaging techniques and compares applications of those techniques in various clinical circumstances. Individuals measurements of cardiovascular disease burdens from multiple aspects, which are closely related to existing biomarkers and clinical outcomes, are recommended as promising candidates for quantitative imaging biomarkers to assess the responses of the cardiovascular system during diabetic regimens.

Orbital Doppler evaluation of blood flow velocities in patients with diabetic retinopathy

BACKGROUND

There have been conflicting results in relation to impaired ocular hemodynamics in the orbital vessels of patients with diabetic retinopathy (DR). Clarification of the early signs of retinopathy in diabetic patients is urgently needed.

AIMS

We aimed to evaluate orbital blood flow velocities using Doppler and gray-scale sonography in patients with DR, and to compare the results with those of their non-diabetic and diabetic peers without retinopathy.

METHODS

Orbital Doppler and gray-scale sonography were performed in 123 patients aged 29-77 who had been divided into 3 groups: non-diabetic controls (n = 25), diabetes and impaired glucose tolerance with minimal clinical retinopathy (n = 74), and diabetes with untreated non-proliferative retinopathy (n = 24). Retinopathy was diagnosed by an ophthalmologist on the basis of fundoscopic examination. The peak systolic (PSV) and end-diastolic (EDV) blood flow velocities, and the resistivity and pulsatile indices, of the ophthalmic artery, central retinal artery, posterior ciliary artery, and central retinal vein were measured.

RESULTS

Compared with healthy controls, the age-adjusted resistivity and pulsatile indices of the ophthalmic artery were significantly higher in patients with DR (p < 0.05). PSV and EDV of the posterior ciliary arteries were significantly lower in diabetic patients with DR. After further adjustment for age, gender, HbA1c, fasting plasma glucose, blood pressure, BMI, cholesterol, HDL, LDL, and triglycerides, only the resistivity index of the ophthalmic artery and the central retinal vein remained significantly higher in patients with DR compared with healthy controls (p < 0.005 after Bonferroni adjustment).

CONCLUSIONS

Resistivity index alteration of the ophthalmic artery and central retinal vein may be prevalent among patients with early changes in DR.

Ophthalmodynamometric pressure in eyes with proliferative diabetic retinopathy measured during pars plana vitrectomy

PURPOSE

To measure ophthalmodynamometric pressure (ODP) during vitrectomy in patients with proliferative diabetic retinopathy (PDR).

DESIGN

Prospective, interventional, consecutive case series.

METHODS

This study included 75 eyes of 75 patients undergoing vitrectomy for PDR. After core vitrectomy, the intraocular pressure was gradually raised using a vented-gas forced-infusion system (VGFI), and the optic nerve head was continuously monitored through a planoconvex contact lens. When the central retinal artery or its branches on the optic nerve head showed pulsations, the pressure was recorded as ODP. Diastolic blood pressure (DBP) and systolic blood pressure (SBP) were measured at the time of ODP measurement. Multiple regression analysis was performed to investigate the relationship between ODP and various explanatory variables: DBP, SBP, age, gender, body mass index, presence of hypertension, serum hemoglobin A1c, serum total cholesterol, fasting plasma glucose, presence of rubeosis iridis, and severity of PDR.

RESULTS

ODP was 63.6 ± 11.5 mm Hg (range 15.5-84.4 mm Hg). The ODP significantly correlated with DBP (r=0.570, P<.0001) and the mean arterial blood pressure (r=0.522, P<.0001), but not with SBP (r=0.121, P=.303). Multiple regression analysis revealed that ODP had a significant correlation with DBP (P<.0001), presence of rubeosis iridis (P<.0001), and severity of PDR (P=.046).

CONCLUSIONS

We measured ODP using VGFI during vitrectomy in patients with PDR. The ODP was significantly associated with DBP. The ODP was lower in patients with rubeosis iridis and severe PDR.

Blood velocity measurement in the posterior segment of the rabbit eye using combined spectral Doppler and power Doppler ultrasound

BACKGROUND

It is challenging for the current Doppler imaging to detect blood flow in small retinal vessels. Power Doppler, with its high sensitivity to detect minimal blood flow, can be used with spectral Doppler to measure blood velocity in small vessels of the eye and orbit.

METHODS

Sixteen eyes of twelve normal pigmented rabbits were studied, using a dedicated small animal, high-resolution imaging unit (Vevo 770) and 17.6 MHz ultrasound probe. Spectral Doppler (ISPPA = 67.1 W/cm(2), ISPTA = 483.7 mW/cm(2), MI = 0.5) was combined with power Doppler (ISPPA = 137.7 W/cm(2), ISPTA = 83.1 mW/cm(2), MI = 0.77) to measure the blood velocity over each identified vessel, including the central retinal artery and vein, branch retinal artery and vein, choroidal vein, and the long and short posterior ciliary artery. Three readings from each vessel were averaged to reduce measurement error. Three indices were calculated from the arterial blood velocity readings: the resistive index, the pulsatility index and the A/B ratio.

RESULTS

The highest arterial blood velocity was measured over the long posterior ciliary artery; peak systolic velocity was 18.29 cm/s and end diastolic velocity was 16.63 cm/s, while the lowest arterial blood velocity was measured over the branch retinal artery; peak systolic velocity was 5.08 cm/s and end diastolic velocity was 3.25 cm/s. On the other hand, the highest venous blood velocity was measured over the choroidal veins (7.0 cm/s), and the lowest venous blood velocity was measured over the branch retinal vein (2.88 cm/s). No statistically significant difference was observed between the nasal and temporal retinal arterial blood velocity. Combining power Doppler with spectral Doppler imaging caused no damage and is a safe technique to measure blood velocity.

CONCLUSION

A combination of spectral Doppler and power Doppler ultrasound can be used as a noninvasive and efficient tool for reproducible measurement of the blood velocity in the posterior segment.

Ocular blood flow in diabetes and age-related macular degeneration

The 2 leading causes of blindness in adults in the industrialized nations, diabetic retinopathy and age-related macular degeneration, have been investigated thoroughly with respect to their pathogenesis. In recent years, it has been discovered that dysfunctional ocular microcirculation appears to play a part in the development of both diseases. In diabetic retinopathy, it has been shown that the disease is associated with early retinal vascular dysregulation. In the later states of the disease, retinal tissue hypoxia is a major trigger of sight-threatening neovascularization. In age-related macular degeneration, there is increasing evidence that reduced blood flow in the choroid is associated with the development and progression of the disease. Knowledge of the pathophysiological vascular states underlying these diseases is essential for the assessment and development of future therapies.

Doppler ultrasonography imaging of hemodynamic alteration of retrobulbar circulation in type 1 diabetic children and adolescents without retinopathy

AIM

We aimed to investigate the retrobulbar blood circulation using Colour Doppler Imaging (CDI) in type 1 diabetic children and adolescents who had no diabetic retinopathy and to compare the results with their healthy peers.

METHODS

Forty-nine patients with type 1 diabetes mellitus with no retinopathy on fundoscopic examination were included in the study. Forty-nine healthy children were defined as the control group. Central retinal artery (CRA), ophthalmic artery (OA) and posterior ciliary artery (PCA) were examined with Doppler US bilaterally. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive indices (RI) for each artery were recorded.

RESULTS

Blood flow velocity of the OA was significantly different in diabetic patients (p<0.05). EDV of the OA was significantly higher (p=0.011) and RI was significantly lower (p=0.027) in patients with diabetes duration of longer than 5 years. RI of the CRA was significantly higher in patients who had higher microalbuminuria levels (p=0.016).

CONCLUSION

EDV of the OA increases and RI of the OA decreases in diabetes duration longer 5 years. Raised AER increases RI of the CRA. These findings may be the initial changes in the arterial circulation before vascular rigidity develops.

Early increase of retinal arterial and venous blood flow velocities at color Doppler imaging in brittle type 1 diabetes after islet transplant alone

Little information is currently available about the role of islet transplantation alone (ITA) on the retinal microcirculation. Our purpose was to investigate with color-Doppler-imaging the effect of ITA after one year on the blood flow velocities of central retinal artery and vein. Central retinal arteries and veins of both eyes of 10 ITA patients were evaluated with color-Doppler-imaging before and one year after transplant. Peak systolic velocity (psv), end diastolic velocity (edv) for arteries and maximum velocity (maxv), minimum velocity (minv) for veins were recorded and compared with a control group of type 1 diabetic patients. At one year, a statistically significant increase of blood flow velocities of central retinal arteries (psv: 6.09+/-0.46 vs. 10.12+/-1.20 cm/s, P=0.01) and veins (maxv: 3.12+/-0.28 vs. 6.12+/-1.00 cm/s, P=0.01) was found only in the ITA patients. An early, significant increase of arterial and venous retinal blood flow velocities was found after ITA.

Transcranial duplex ultrasound of the ophthalmic artery

The purpose of this study was to identify the ophthalmic artery (OA) by means of transcranial color-coded sonography using a new approach via the transtemporal bone window and to compare blood flow measurements with values obtained from the transorbital approach. A total of 105 subjects were included. Two individuals had an insufficient unilateral bone window, according to our inclusion criteria. Of the remaining 208 OAs, 206 (99%) could successfully be insonated via the transorbital approach and 190 (91%) via the transtemporal approach. Transorbital systolic and diastolic flow velocity (FVs) ranged between 15 and 67 cm/s (mean +/- SD: 35 +/- 10) and 4 to 36 cm/s (14 +/- 5), pulsatility index ranged between 0.4 to 2.8 (1.2 +/- 0.4). Transtemporal systolic and diastolic FVs ranged between 15 and 58 cm/s (33 +/- 9) and 4 to 25 cm/s (11 +/- 4). Transorbital and transtemporal FVs correlated significantly (p = 0.01). Our study demonstrates that transtemporal insonation of the proximal intracranial OA is feasible. Whenever OA assessment for analysis of collateral function is required, this simple approach, avoiding direct eye bulb insonation, should be considered.

Compromised arterial function in human type 2 diabetic patients

Diabetes is associated with a perturbation of signaling pathways in vascular tissue, which causes vasomotor dysfunction such as hypertension and accelerated atherosclerosis. In the present study, the mechanisms of vasomotor dysfunction, Akt (Thr308 and Ser473) phosphorylation and expression of endothelial NO (nitric oxide) synthase, and inducible NO synthase were investigated in human diabetic internal mammary arteries. The phospho-Akt (Thr308) level in arteries from diabetic patients was reduced to about one-half of the level in nondiabetic patients, suggesting impaired insulin signaling in human diabetic vascular tissue. Augmented vasoconstriction was observed in diabetic arteries, due in part to deficiency of basal and stimulated NO production. This correlated with decreased endothelial NO synthase expression and activity in diabetic vessels. The sensitivity of diabetic vessels to the NO donor, sodium nitroprusside, was reduced as well, suggesting that NO breakdown and/or decreased sensitivity of smooth muscle to NO are also responsible for abnormal vasoconstriction. In addition, the abnormal vasoconstriction in diabetic vessels was not completely abolished in the presence of Nomega-nitro-L-arginine methyl ester, revealing that NO-independent mechanisms also contribute to vasomotor dysfunction in diabetes. In conclusion, diabetes downregulates the Akt-signaling pathway and compromises human arterial function through a decrease in NO availability as well as through NO-independent mechanisms.