Resistance Index Of Central Retinal Artery Research Articles

Association between resistivity index of central retinal artery and severity of diabetic retinopathy.

Diabetic retinopathy (DR) is a leading cause of ocular morbidity. Its progression depends mainly on retinal vasculature and ocular blood flow. Color Doppler imaging (CDI) is a noninvasive imaging technique that measures blood flow velocity. The resistivity index (RI), calculated by the CDI, reflects the vascular resistance distal to the measuring location. RI is independent of the doppler angle and position of the patient, making it a reliable and reproducible parameter. To the best of our knowledge, there is only one study in literature studying the association between resistivity index (RI) of the central retinal artery (CRA) and severity of DR. To determine the association between RI of CRA and severity of DR. To determine the association between RI of CRA and spectral-domain optical coherence tomography (SD-OCT) biomarkers for DR. Type II diabetics visiting our OPD underwent DR screening and were graded into three categories according to ETDRS classification which include Group A-No diabetic retinopathy (No DR), Group B-Nonproliferative diabetic retinopathy (Moderate-Severe-Very Severe NPDR), and Group C-Proliferative diabetic retinopathy (PDR). SD-OCT was performed. Ultrasonic color doppler imaging was done. RI of the CRA was noted. It was compared between the three groups and its association with severity of DR and OCT biomarkers (central subfield thickness, cube average thickness and ellipsoid zone disruption) was studied. 56 eyes of 28 patients were included in our study with 20 in Group A,14 in Group B, and 22 in Group C. RI of CRA compared within groups showed statistically significant association with severity of DR (P < 0.001). The presenting BCVA (LogMar) showed positive correlation with RI in all groups. OCT biomarker central subfield thickness showed a positive correlation with RI in Groups A (P < 0.001) and B. Ellipsoid zone (EZ) disruption showed a statistically significant association with RI in Group C (P < 0.001). The RI of CRA is a reliable biomarker for the assessment of the severity of DR. Patients with high RI of CRA had higher chances of EZ disruption and presented with poor visual acuity.

Ocular blood flow and retinal, choroidal, and retinal nerve fiber layer thickness in children with familial Mediterranean fever with at least five attacks.

This study aimed to evaluate ocular blood flow and, retinal, choroidal and retinal nerve fiber layer thickness in children with familial Mediterranean fever (FMF) with patients who had at least five attacks. Fifty-six patients with FMF and 56 healthy subjects were enrolled in the study. Each participant's choroidal thickness (CT) and retinal thickness (RT) measurements were performed in the foveola and at horizontal nasal and temporal quadrants within 500-μm intervals up to 1.500μm from the foveola using spectral-domain optical coherence tomography as well as the retinal nerve fiber layer thickness (RNFLT). Disc boundaries were determined manually by identifying seven points on the inner edge of the scleral ring. Following complete ophthalmological evaluation, peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistivity index (RI) values in the central retinal artery (CRA), ophthalmic artery (OA), and nasal posterior ciliary artery (NPCA) were measured using color Doppler ultrasonography (CDU) in the left eyes of the patients diagnosed with FMF and the controls. The results were subsequently compared. No statistically significant differences were observed between the groups in terms of all RNFLT quadrant and RT measurements. All CT measurements were thinner in patients with FMF than in the controls (For Central and Temporal_1500 p = 0.01; For Temporal_500, Nasal 500 and Nasal_1000 p < 0.001; Temporal_1000 p = 0.002) except than the Nasal_1500 point. For nasal_1500 p = 0.121). The PSV and EDV values in the OA, CRA, and NPCA were significantly lower in patients with FMF compared to healthy controls (p < 0.001 for all). In contrast, the RI values of all arteries were significantly higher than in the control group (Regarding OA, CRA and NPCA RI, p = 0.003, p = 0.039, and p = 0.039, respectively). The results of this study support the idea that chronic inflammation and frequent attacks in FMF may have an effect on decreased ocular blood flow and choroidal thinning.

Changes in ocular hemodynamics in patients recovered from COVID-19

To evaluate the severity of hemodynamic changes in the ocular vessels of patients recovered from COVID-19. The study included 44 patients (88 eyes) aged 28-60 years, among them 24 (54.5%) women and 20 (45.4%) men, with SARS-CoV-2 infection confirmed by PCR no more than 2 months prior to enrollment and with no ophthalmological complaints within 2 months before the disease, as well as 20 healthy volunteers (40 eyes). At the time of the study all patients had a negative PCR result for SARS-CoV-2. The patients were divided into 2 groups. The first group comprised 24 patients who did not take any anticoagulants during the treatment. The second group consisted of 20 patients who received anticoagulants (Rivaroxaban (Xarelto)) at a dosage of 10 mg per day for 1-1.5 months. The maximum systolic (Vs), end-diastolic (Vd) blood flow velocity, as well as resistance index (RI) in the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCA) were measured in all study patients with the ultrasound imaging system VOLUSON E8 Expert («Kretz», USA). Additionally, the flowmetry method was used to assess the volumetric ocular blood flow (VOBF) on Ocular Blood Flow Analyzer system («Paradigm Medical Industries, Inc.», USA). In the first group, a decrease in Vs and Vd was noted amid a significant increase of RI in CRA and SPCA, as well as an increase of RI in OA compared with the age-normal values (p<0.05). In the second group, a decrease in Vs and Vd was noted amid a significant increase of RI in CRA, as well as a decrease in Vs in SPCA and an increase of RI in OA relative to the age-normal values (p<0.05). A decrease in VOBF was noted in the first group in comparison to the second group and the age norm (p<0.05). Blood flow velocity parameters in the ocular vessels are reduced in patients recovered from COVID-19 compared to the age-normal values. There was a significant decrease in volumetric ocular blood flow parameters in COVID-19 patients who did not take any anticoagulants compared to the age-normal values. Anticoagulants intake has a positive impact on hemodynamic characteristics in the ocular vessels and volumetric ocular blood flow in patients with COVID-19.

Correlation of Measurements From Doppler Ultrasound and Optical Coherence Tomography in Glaucoma.

To relate the changes in ocular structure and hemodynamic response in primary open-angle glaucoma (POAG). Patients with POAG (n=46) and control subjects (n=53) were recruited. Retinal nerve fiber layer and ganglion cell complex were evaluated using optical coherence tomography (OCT). Blood flow was characterized in ophthalmic artery (OA) and central retinal artery (CRA) using color Doppler ultrasonography (CDU), and resistivity index (RI) was calculated. Measurements from CDU and OCT were statistically correlated and the degree of the association was examined. Receiver operating characteristics was produced based on RI and optimal threshold was determined. In POAG patients, OCT revealed neuronal damage and CDU indicated increased resistance to arterial flow. Flow dynamics correlated negatively with the ocular tissue dimensions, sufficiently establishing an association between the ocular structure and its hemodynamic response. Based on the possibility of indirect POAG diagnosis with CDU, threshold 0.7 for RI of OA yielded 73.9% sensitivity and 77.4% specificity in distinguishing the cases of POAG from the controls. Threshold of 0.66 for RI of CRA, had higher specificity of 83%, but lower sensitivity of 52.1%. Ocular flow exhibits different characteristics in individuals with POAG than normal. The changes associated with the underlying neuronal structure, suggesting the possibility of a potential new diagnostic biomarker for POAG. This justifies further studies with a larger cohort, examining the ocular flow with CDU in POAG and comparing it against OCT findings for establishing the power of CDU in differential diagnosis or glaucoma progression.

OCT ANGIOGRAPHY AND DOPPLER ULTRASOUND IN HYPERTENSION GLAUCOMA.

The main aim of this work was to find out if there is acorrelation between vessel density (VD) and results of measured perfusion values in ophthalmic artery and in central retinal artery of the same eye in agroup with hypertension glaucoma (HTG). The file included 20 patients with HTG, thereof 13 women of average age 68.7 years (49-80 years) and 7 men of average age 58.4 years (27-81 years). Criteria for inclusion in the study: visual acuity 1,0 with possible correction less than ±3 diopters, approximately the same changes in visual fields in every patient, intraocular pressure (IOP) less than 18 mmHg, no other ocular or neurological diseases. VD was measured by Avanti RTVue XR by Optovue firm, perfusion parameters were measured using Doppler ultrasound with Affinity 70G machine by Philips firm. The peak systolic velocity (PSV) and end diastolic velocity (EDV) and resistance index (RI) were measured both in ophthalmic artery (AO) and in central retinal artery (CRA). Visual field (VF) was examined by quick threshold glaucoma program by Medmont M 700 machine. The sum of sensitivities in apostilbs (abs) was evaluated in the range 0-22 degrees of visual field. The results of sensitivities in visual field were compared to VD and perfusion parameters in CRA and AO of the same eye. Pearsonscorrelation coefficient (p=0,05) was used to assess the dependency between chosen parameters. By comparing VF and VD from measured areas, strong correlation (r=0.64, resp. 0.65) was revealed. It was then proved that VD (WI-VDs) correlates with RICRA weakly (r=-0.35) and moderately strongly (WI-VDa r=-0.4, PP-VDs r=-0.43 and PP-VDa r=-0.45). This means that with increasing resistance index in CRA the density in VD decreases. The other correlations between VD and perfusion parameters (PSV and EDV) in CRA and AO were not significant. Measured values showed that the vascular component of VD has ahuge impact on the changes in visual fields in HTG. Weak to moderate influence exists between VD and RI in CRA. OCTA has proven to be more suitable than Doppler ultrasound for determining the condition of blood circulation in the eye.

Abnormal retrobulbar blood flow variables in central serous chorioretinopathy.

To evaluate if the retrobulbar blood flow variables were deteriorated in central serous chorioretinopathy (CSC) patients. We included 25 CSC patients and 25 healthy subjects. We used color Doppler ultrasonography to assess the ophthalmic artery (OA), the central retinal artery (CRA), and the posterior ciliary arteries (PCA) for peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index (RI). Mean ages of the patients and controls were 42.3 ± 8.5 and 41.3 ± 9.4 years, respectively (P = .853). There were no significant differences between the two groups with regard to the values of PSV, EDV, and RI of CRA (P = .406, P = .627, P = .227) and PCA (P = .785, P = .403, P = .935, respectively). The PSV and EDV of OA were lower in the CSC patients (P = .005, P = .024, respectively). Whereas the RI of OA was not significantly different (P = .729). Submacular choroidal thickness (SCT) was greater in CSC patients (P < .001). There was a negative correlation between SCT and PSV of PCA (P = .022, r = -0.457) and between SCT and EDV of PCA (P = .004, r = -0.560) in CSC patients. Hemodynamic changes in OA and a negative correlation between PCA values and SCT suggest ocular circulatory dysfunction in patients with CSC.

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

BackgroundThe 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.MethodsEighty-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.ResultsMean 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).ConclusionsResistive index of CRA is a reliable bioimaging biomarker for the severity of DR.

Longitudinal follow-up study of the retrobulbar and intrarenal hemodynamics in patients with T2DM.

Objective:The primary aim of this study is to examine the hemodynamics of retrobulbar and intrarenal in the changes of early stage of type 2 diabetes mellitus (T2DM) patients from 2000 to 2015 and to assess incidence associated with diabetic kidney disease (DKD) and diabetic retinopathy (DR).Method:Our study contained 60 subjects newly diagnosed of T2DM were divided into 2 groups base on the mean resistive index (RI) (≤0.7 and >0.7) of hemodynamic and to compare between-group differences of the early changes in hemodynamics of retrobulbar and intrarenal and also to conclude the incidences of diabetic kidney disease (DKD) and diabetic retinopathy (DR)subsequently with a long follow-up duration(2000–2015). First, to compare the mean RI of central retinal artery (CRA) between 2 groups. Second, to compare the mean RI of intrarenal hemodynamics in the bilateral interlobular renal arteries, renal function parameters (blood urea nitrogen (BUN), creatinine (Cr), blood glucose parameters (glycosylated hemoglobinA1c (HbA1c), fasting plasma glucose (FBG), and 2-hour postprandial blood glucose (2hPBG)), glomerular filtration rate (GFR), albumin excretion rate (AER), and urine albumin-to-creatinine ratio (UACR) between 2 groups.Results:First part of our follow-up studies was to compare hemodynamic RI index of retrobulbar in years of 2000 and 2015, both renal function and blood glucose parameters were fund significantly enhanced in subject group RIs ≤0.7. Incidence of DKD and DR was notably lower in group RIs ≤0.7 than group RIs > 0.7, difference was statistically significant (P < .05). Incidence of HbA1c ≤7% was higher in group RIs ≤0.7 than group RIs >0.7, but difference was not statistically significant (P > .05). Incidence of proliferative diabetic retinopathy (PDR) was notably lower in group RIs ≤0.7 than group RIs >0.7, but the difference was not statistically significant (P > .05). Second part of our follow-up studies was to compare hemodynamic RI index of interlobular renal in years of 2000 and 2015, both renal function and blood glucose parameters were fund significantly enhanced in subject group RIs ≤0.7. Compared data of various incidences from first part of study were coherent with second part. (Incidence of DKD and DR was notably lower in group RIs ≤0.7 than group RIs >0.7, difference was statistically significant (P < .05). Incidence of HbA1c ≤7% was higher in group RIs ≤0.7 than group RIs >0.7, but difference was not statistically significant (P > .05). Incidence of PDR was notably lower in group RIs ≤0.7 than group RIs >0.7, but the difference was not statistically significant (P > .05).Conclusions:RIs of retrobulbar and interlobular renal which would serve as a good predictors for the hemodynamics changes in retrobulbar and intrarenal would assess incidence of DKD and DR during the preclinical stage in long-term range excluding renal function and HbA1c in T2DM patients.

Intima-media thickness of the common carotid arteries as a marker of retinopathy and nephropathy in sickle cell disease.

PurposeThis study was conducted to test the hypothesis that the carotid intima-media thickness (CIMT) is higher in patients with sickle cell disease (SCD) than in the normal population, and to determine the relationships of the CIMT with central retinal artery (CRA) and renal artery Doppler indices.MethodsForty-four confirmed steady-state SCD patients aged 16 years and above were recruited consecutively. The Doppler velocimetric indices of their right renal artery and both CRAs were obtained. The CIMT was also measured on each side via B-mode ultrasonography. The subjects were categorized by age and sex. Mean and median values for each group were determined. The Spearman correlation test was used to quantify the relationships between CIMT and the Doppler parameters.ResultsThe participants had a median age of 24.50 years (interquartile range, 12.50 to 36.50 years). Twenty-three were men (52.3%) and 21 were women (47.7%). The median CIMT was 0.70 mm (IQR, 0.50 to 0.90 mm). Significant correlations with the CIMT were found for the CRA peak systolic velocity (r=0.312, P=0.003), the renal artery resistivity index (RI) (r=0.284, P=0.007), and the renal artery pulsatility index (PI) (r=0.273, P=0.010). There was no significant relationship between the CIMT and the CRA end-diastolic velocity, CRA RI, or CRA PI.ConclusionCIMT in SCD patients was higher than in the previously reported age groups of the reference populations. In addition, the CIMT was significantly correlated with the CRA peak systolic velocity, the renal artery RI, and the renal artery PI.

Color Doppler imaging of ocular hemodynamic changes in patients with rheumatoid arthritis unrelated to disease activity.

We aimed to investigate how orbital blood flow rates in patients with rheumatoid arthritis (RA) are affected by the active and remission phase of the disease. This prospective study included a total of 56 patients with RA (study group) and 24 control individuals (control group). All RA patients were divided into two groups, as active (Group 1) and remission (Group 2) according to the disease activity index (DAS 28) score. For each eye, retrobulbar vascular structures were evaluated [central retinal artery (CRA), posterior ciliary artery (PCA), and ophthalmic artery (OA)], respectively. The peak systolic velocity (PSV) and end-diastolic velocity (EDV) values were obtained for each artery and the vascular resistance index (RI) measurement was calculated. The median RI of the OA was 0.70 (0.57; 0.79) in the control group, 0.77 (0.55; 0.87) in group 1, and 0.73 (0.47; 0.87) in group 2. The median RI in the PCA was 0.70 (0.56; 0.82) in the control group, 0.76 (0.52; 0.88) in the group 1, and 0.74 (0.52; 0.86) in the group 2. The median RI of CRA was 0.73 (0.48; 0.81) in the control group, 0.71 (0.64; 0.81) in group 1, and 0.68 (0.61; 0.85) in group 2. The RI value was a significant difference between control and group 1 (p < 0.05). Active and remission RA patients had different effects on the flow rate of eye blood vessels.

Color Doppler imaging of orbital vasculature before and after orbital decompression in thyroid eye disease

ABSTRACTPurpose: To measure alterations in orbital blood flow parameters using color Doppler imaging (CDI) before and after orbital decompression in patients with moderate to severe thyroid eye disease (TED).Methods: Resistance index (RI) and maximum and minimum velocity of ophthalmic artery (OA), superior ophthalmic vein (SOV), and central retinal artery (CRA) of 24 eyes (14 patients) with TED were measured before and at least 3 months after cosmetic orbital decompression procedure (single or double walls) using CDI. Complete eye examination was performed to define the severity (EUGOGO classification) and activity (clinical activity score) of TED.Results: Median OA (p = 0.003) and CRA (p = 0.001) resistance indices were significantly reduced postoperatively. Significant differences were found in maximum (p = 0.001) and minimum (p = 0.014) velocity of SOV before and after surgery. While a significant decrease in exophthalmometry was observed after the orbital decompression (p = 0.031), intraocular pressure changes were not significant (p = 0.182).Conclusion: Orbital decompression procedure led to a significant reduction of RI in both CRA and OA in patients with TED.

Evaluation of retrobulbar blood flow and choroidal thickness in patients with rheumatoid arthritis.

To evaluate whether retrobulbar blood flow and choroidal thickness (CT) are affected in patients with rheumatoid arthritis (RA), and the relationship between these values. We evaluated 40 eyes of 20 RA patients and 40 eyes of 20 healthy controls. The enhanced depth imaging optical coherence tomography, color Doppler imaging, was held. Statistical analysis was performed. Peak systolic velocity (PSV) of ophthalmic (OA) and central retinal artery (CRA) were significantly higher in RA. No significant difference was observed when end-diastolic velocity (EDV) of OA and CRA was compared between the groups. The resistivity index (RI) of OA and CRA was higher in RA. Perifoveal/subfoveal CT was lower in RA. Negative correlation was detected between the RI of OA and the perifoveal CT, and a positive correlation was detected between RI of CRA and CT. Ocular hemodynamics is effected by RA and can exaggerate ocular complications of various vascular diseases such as diabetes mellitus, hypertension, retinal vascular occlusions.

Parameters of ocular fundus on spectral-domain optical coherence tomography for glaucoma diagnosis.

In this review, we summarize the progression of several parameters assessed by spectral-domain optical coherence tomography (SD-OCT) in recent years for the detection of glaucoma. Monitoring the progression of defects in the retinal nerve fiber layer (RNFL) thickness is essential. Imaging and analysis of retinal ganglion cells (RGCs) and inner plexiform layer (IPL), respectively, have been of great importance. Optic nerve head (ONH) topography obtained from 3D SD-OCT images is another crucial step. Other important assessments involve locating the Bruch's membrane opening (BMO), estimating the optic disc size and rim area, and measuring the lamina cribrosa displacement. Still other parameters found in the past three years for glaucoma diagnosis comprise central retinal artery resistive index, optic disc perfusion in optical coherence tomography angiography (OCTA) study, peripapillary choroidal thickness, and choroidal area in SD-OCT. Recently, several more ocular fundus parameters have been found, and compared with the earlier parameters to judge the accuracy of diagnosis. While a few of these parameters have been widely used in clinical practice, a fair number are still in the experimental stage.

Enhancement of scutellarin oral delivery efficacy by vitamin B12-modified amphiphilic chitosan derivatives to treat type II diabetes induced-retinopathy

BackgroundDiabetic retinopathy is the most common complication in diabetic patients relates to high expression of VEGF and microaneurysms. Scutellarin (Scu) turned out to be effective against diabetes related vascular endothelial cell dysfunction. However, its clinical applications have been limited by its low bioavailability. In this study, we formulated and characterized a novel intestinal target nanoparticle carrier based on amphiphilic chitosan derivatives (Chit-DC-VB12) loaded with scutellarin to enhance its bioavailability and then evaluated its therapeutic effect in experimental diabetic retinopathy model.ResultsChit-DC-VB12 nanoparticles showed low toxicity toward the human colon adenocarcinoma (Caco-2) cells and zebra fish within concentration of 250 μg/ml, owing to good biocompatibility of chitosan. The scutellarin-loaded Chit-DC-VB12 nanoparticles (Chit-DC-VB12-Scu) were then prepared by self-assembly in aqueous solution. Scanning electron microscopy and dynamic light scattering analysis indicated that the Chit-DC-VB12-Scu nanoparticles were spherical particles in the sizes ranging from 150 to 250 nm. The Chit-DC-VB12-Scu nanoparticles exhibited high permeation in Caco-2 cell, indicated it could be beneficial to be absorbed in humans. We also found that Chit-DC-VB12 nanoparticles had a high cellular uptake. Bioavailability studies were performed in Sprague–Dawley rats, which present the area under the curve of scutellarin of Chit-DC-VB12-Scu was two to threefolds greater than that of free scutellarin alone. Further to assess the therapeutic efficacy of diabetic retinopathy, we showed Chit-DC-VB12-Scu down-regulated central retinal artery resistivity index and the expression of angiogenesis proteins (VEGF, VEGFR2, and vWF) of retinas in type II diabetic rats.ConclusionsChit-DC-VB12 nanoparticles loaded with scutellarin have better bioavailability and cellular uptake efficiency than Scu, while Chit-DC-VB12-Scu nanoparticles alleviated the structural disorder of intraretinal neovessels in the retina induced by diabetes, and it also inhibited the retinal neovascularization via down-regulated the expression of angiogenesis proteins. In conclusion, the Chit-DC-VB12 nanoparticles enhanced scutellarin oral delivery efficacy and exhibited potential as small intestinal target promising nano-carriers for treatment of type II diabetes induced-retinopathy.

Effects of video work on the ocular vascular hemodynamic and visual of the operators

Objective: To investigate the effects of long time video display terminal (VDT) operation on the ocular vascular hemodynamic and visual acuity. Methods: During March and October 2015, 120 cases of video monitoring warriors were selected as study group, another 155 cases of logistics personnel as the control group. The low vision of the two groups was calculated and compared, and the color Doppler flow imaging was used to measure the central retinal artery (CRA) , short posterior ciliary artery (SPCA) , anterior ciliary artery (ACA) , (peak systolic velocity, PSV) , end diastolic velocity (EDV) and (resistance index (RI) . The differences of hemodynamic parameters between these two groups were evaluated, and the relationship between the visual acuity and each hemodynamic parameter was analyzed. Results: The visual acuity of the study group was[0.8 (0.4-1.2) ], much lower than the control group, and the rate of low version in the study group was 40.00%, much higher than that of the control group. Compared with the control group, both of ACA and CRA of SPCA, PSV and EDV in the study group were decreased, while RI of CRA, ACA were increased (P<0.05) ; Compared with the control group, no statistical significance was found in the RI of SPCA in the study group (P>0.05) . The PSV and EDV were negatively correlated with visual acuity (r value of PSV and visual acuity were -0.352, -0.265 and -0.304; r value of EDV and visual acuity were -0.324, -0.348 and -0.365, while RI was positively correlated with visual acuity (r value were 0.363, 0.326 and 0.344) . Conclusion: Our data suggest that long time video operation may be associated with changes of ocular vascular hemodynamic parameters and raise the incidence of low vision.

Resistive Index of Ophthalmic Artery as a Bioimaging Biomarker for the Severity of Diabetic Retinopathy

Objective: To assess the resistive index (RI) of ophthalmic artery (OA) and central retinal artery (CRA) as a bioimaging biomarker for the severity of diabetic retinopathy, for the first time. Design: Tertiary care center based cross sectional study. Setting: RI in OA and 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 studied using SD-OCT. Participants: Sample size was calculated using 95% confidence interval. 69 consecutive cases of type 2 diabetes mellitus between the ages of 40 and 70 years were included after informed consent. According to Early Treatment Diabetic Retinopathy Study (ETDRS) classification cases were grouped as: diabetes mellitus with no retinopathy (No DR) (n=22); non-proliferative diabetic retinopathy (NPDR) (n=25); and Proliferative Diabetic Retinopathy (PDR) (n=22). Healthy control subjects of similar age were included (n=22). Main outcome measures: RI in OA and CRA. Results: A significant increase in RI of OA and CRA was observed with increased severity of DR. A significant positive correlation of RI of OA and CRA with CST, CAT and grades of EZ disruption and a negative correlation with RNFL thickness was observed. RI of OA was found to be a significant independent predictor of severity of DR [multivariate analysis OR=0.00, p<0.001; area under receiver operating characteristic curve analysis=0.941-1.000, p<0.001]. Conclusions: Resistive index of OA is a bio imaging biomarker for the severity of DR.

Assessment of orbital blood flow velocities in retinopathy of prematurity.

The purpose of this study is to evaluate whether the presence of any stage retinopathy of prematurity (ROP) alters central retinal artery (CRA) and ophthalmic artery (OA) blood flow parameters in premature infants. The patients were divided into two groups according to the development of ROP; those who have ROP were defined as group I, those without ROP were defined as group II. Ninety eyes of 45 patients in group I and 40 eyes of 20 patients in group II were investigated. The blood flows in the CRA and OA were measured using ultrasound color doppler imaging (CDI) that allows to evaluate the peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI). The results were compared between two groups of subjects. There were no significant differences in the PSV, EDV, and RI of CRA between two groups (P=0.09, P=0.20 and P=0.63, respectively). The mean PSV value of OA in group I was found to be significantly higher than the one in group II (P<0.05), but there were no significant differences in the mean EDV and RI values of OA between two groups (P=0.40, P=0.17 respectively). The subgroup analysis revealed that the ocular blood dynamics were not found to be significant between eyes with stage I ROP and eyes with stage II ROP (P>0.05), whereas the difference in the mean PSV values of OA were found to be significant among the eyes with stage 1 ROP, eyes with stage 2 ROP, and eyes without ROP (P=0.03). This study demonstrated significant alterations in systolic flow velocities in the OA predicted by CDI in infants with ROP.

The Effects of 23-Gauge Pars Plana Vitrectomy on Orbital Circulation Using Doppler Ultrasonography in Diabetic Macular Edema with Epiretinal Membrane and Taut Posterior Hyaloid

ABSTRACTPurpose: To evaluate using Doppler ultrasonography (DUS) how pars plana vitrectomy (PPV) affects orbital circulation in diffuse diabetic macular edema (DME) associated with either the epiretinal membrane (ERM) or taut posterior hyaloid (TPH).Methods: The sample included 46 eyes of 42 patients with DME associated with the ERM (n = 22, Group 1) or TPH (n = 24, Group 2). All participants received panretinal laser photocoagulation and antivascular endothelial growth factor injections preoperatively and underwent 23-gauge PPV combined with ERM or TPH removal and internal limiting membrane (ILM) peeling. Pre- and postoperative peak systolic velocity (PSV), end-diastolic velocity (EDV), and the resistivity index (RI) of the ophthalmic artery (OA), central retinal artery (CRA), posterior ciliary artery (PCA), and central retinal vein were measured with DUS.Results: Statistically significant decreases in the PSV and EDV of the OA, CRA, and PCA were detected in all groups. In Group 1, the PSV of the OA and CRA as well as the EDV and PSV of the PCA declined significantly. In Group 2, the EDV of the OA and both the PSV and EDV of the CRA and PCA decreased. Postoperatively, the CRA’s PSV and EDV were lower in Group 2, while the preoperative and postoperative RI of the CRA and preoperative RI of the PCA were greater in Group 2 than in Group 1. Changes in the CRA’s RI, PSV, and EDV were greater in Group 2 after surgery.Conclusions: 23-Gauge PPV combined with ERM or TPH removal and ILM peeling in DME reduces blood flow rates of both choroidal and retinal vessels. In eyes with TPH, the RIs of the CRA and PCA were significantly greater preoperatively and the changes in the CRA’s RI, PSV, and EDV were greater postoperatively. The removal of the TPH may play a role in regulating blood flow.

The Relationship between Central Retinal Artery Resistive Index and Measures of Renal Function in Type 2 Diabetes

Background: Renal and ocular vessels are some of the major vessels affected in patients with diabetes, and the involvement of these vessels is independent risk factors for other complications. Hemodynamic flow in arteries may be assessed by using measures such as resistive index, which is a non-invasive measure of the resistance in vessels. The association between retinopathy and nephropathy has been conflicting. This study assessed the relationship between resistive index of the central retinal artery and indices of nephropathy in type 2 diabetes. Method: This cross-sectional study examined 74 Nigerian diabetics who were selected consecutively from the out-patient diabetic clinic of a tertiary hospital in South-West Nigeria. Doppler ultrasound was used to determine the resistive index of the central retinal artery along with the right renal artery. The urinary and serum biochemical parameters were also done to determine the urinary albumin excretion and the glomerular filtration rate. Results: The mean age of participants was 59.62 ± 9.55 years. The mean central retinal artery resistive index (CRARI) was 0.77 ± 0.06, with 65 (87.8%) of the participants having elevated CRARI. There was no statistical difference between patients with normal CRARI and elevated CRARI in respect of their urinary albumin excretion (p = 0.796). There was no significant correlation between CRARI and estimated glomerular filtration rate (r = 0.120; p = 0.309) and right renal artery resistive index (r = 0.068; p = 0.564). Conclusion: This study demonstrates that central retinal artery resistive index (CRARI) may not be a predictor of renal function in diabetics.

Central retinal artery resistive index and optical coherence tomography in assessment of glaucoma progression.

To assess the relation between central retinal artery (CRA) resistive index (RI) and retinal nerve fiber thickness measured by optical coherence tomography (OCT) in assessment of disease progress in cases of open angle glaucoma. Twenty-three patients with diagnosed open angle glaucoma were included in this study. They were examined by colored duplex ultrasonography of CRA with estimation of RI of CRA and ophthalmic artery (OA) with estimation of CRA/OA RI ratio as well as OCT measurement of the average retinal nerve fiber layer (RNFL) thickness in order to assess the disease progress. There was strong inverse relation between the increased RI in CRA as well as the increased CRA/OA RI ratio and the decrease in average RNFL thickness in cases of open angle glaucoma. Assessment of CRA RI can indirectly assess the vascular changes associated with glaucoma and can assess the degree of retinal atrophy helping in evaluating prognosis thus guiding the choice of treatment.