Choroidal circulation in diabetic patients

Chorio-retinal vessel density in women affected by functional hypothalamic amenorrhea: a monocentric observational cross-sectional study to evaluate the impact of hypoestrogenism on chorio-retinal vascularization

PURPOSE

Functional hypothalamic amenorrhea (FHA) is characterized by an estrogen deficiency which in turn can cause vascular dysfunction. The aim of this study is to evaluate any changes in the chorio-retinal circulation in patients affected by FHA. 24 patients with FHA and 24 age-matched controls underwent a gynecological evaluation and an OCT angiography (OCTA) to study chorio-retinal vascularization.

RESULTS

OCTA in FHA patients showed an increase in vessel density in the choriocapillaris (CC) layer (both in the fovea area, at 5% p value = 0.037 and in the whole area, at 5% p value = 0.028) and an increase in vascular density in the deep fovea (DVP) (at 10% p value = 0.096) in the whole district compared to controls. Simple linear regressions show a significant negative association between CC vessel density and insulin (p = 0.0002) and glucose values (p = 0.0335) for the fovea district and a negative association between DVP vessel density and endometrial thickness (at 10%, p value: 0.095) in the whole district.

CONCLUSION

Our study shows that CC vessel density is increased in women affected by FHA. This could represent a compensation effort to supply the vascular dysfunction caused by estrogen deficiency. We also found an increasing trend in vascular density in DVP associated with the decrease of endometrial thickness, an indirect sign of estrogenization. Considering that these changes occur in absence of visual defects, they could be used as a biomarker to estimate hypoestrogenism-induced microcirculation changes before clinical appearance.

Changes in the choroid detected by ultrawide-field optical coherence tomography angiography in type 2 diabetes mellitus patients without diabetic retinopathy

AIM

The study objective was to investigate the choroidal changes in type 2 diabetes mellitus (T2DM) patients without diabetic retinopathy (DR).

METHODS

This was a cross-sectional study. Controls without diabetes and T2DM patients without DR (NDR) were included. Ultrawide-field (24 × 20 mm2) optical coherence tomography angiography (OCTA) was performed to analyse choroidal thickness and vessel density. All OCTA images were divided into 3 × 3 grids. The grid centre was considered the central area, while the rest was defined as the peripheral area.

RESULTS

No differences between groups were observed in the flow density of the choriocapillaris (CC), choroidal thickness (ChT) and choroidal vascular index (CVI) of the large and medium choroidal vessel (LMCV) in the central area. In the eight peripheral areas, the mean flow density of the CC did not differ between the groups, while the mean CVI and ChT were decreased in the NDR group (P< 0.05). In each peripheral area, the mean CVI and ChT were decreased in the NDR group (P< 0.05, except in the infratemporal area and nasal area for ChT and in the infratemporal area for CVI). In the correlation analysis, both mean peripheral CVI and ChT correlated with age and the duration of diabetes.

CONCLUSION

Early choroidal lesions tended to be peripheral in the LMCV in patients with diabetes without DR and correlated with age and the duration of diabetes.

Can orbital artery resistive indexes detect complications of diabetes in the prediabetic phase?

AIM

Prediabetic patients have generalized microvascular dysfunction, which leads to end-organ damage, just like diabetes. Therefore, prediabetes is not just a mild elevation in blood sugar, and early detection and prevention of possible complications should be the main goal. Color Doppler imaging (CDI) provides morphologic and vascular information on various diseases. The Resistive Index (RI) is a widely used measure of resistance to arterial flow and is calculated from the CDI. CDI evaluation of vessels in the retrobulbar region may be the first sign of micro- and macrovascular complications.

METHOD

Consecutively, 55 prediabetic patients and 33 healthy subjects were recruited for the study. Prediabetic patients were divided into three groups according to their fasting and postprandial blood glucose values. The groups included an impaired fasting glucose (IFG) group (n = 15), an impaired glucose tolerance (IGT) group (n = 13), and an IFG+IGT group (n = 27). The RI of the ophthalmic artery, posterior ciliary artery, and central retinal artery were measured in all patients.

RESULTS

The orbital artery, central retinal artery, and posterior cerebral artery mean RI of prediabetic patients (0.76 ± 0.06, 0.69 ± 0.03, and 0.69 ± 0.04, respectively) were significantly higher than those of the healthy group (0.66 ± 0.04, 0.63 ± 0.04, and 0.66 ± 0.04, respectively; p < 0.001; Student's t-test). The mean ophthalmic artery RI of the healthy, IFG, IGT, and IFG+IGT groups were 0.66 ± 0.39, 0.7 ± 0.27, 0.72 ± 0.29, and 0.82 ± 0.16, respectively, with a significant difference between the groups (p < 0.001, ANOVA). The mean central retinal artery RI of the healthy, IFG, IGT, and IFG+IGT groups were 0.63 ± 0.04, 0.66 ± 0.02, 0.7 ± 0.02, and 0.71 ± 0.02, respectively (p < 0.001, post-hoc Tukey). The mean posterior cerebral artery RI of the healthy, IFG, IGT, and IFG+IGT groups were 0.66 ± 0.04, 0.66 ± 0.04, 0.69 ± 0.03, and 0.71 ± 0.03, respectively, with a significant difference between the groups (p < 0.001 Fisher ANOVA).

CONCLUSION

Increased RI may be the first sign of developing retinopathy, as well as the first sign of microangiopathies occurring simultaneously in the coronary, cerebral, and renal vessels. Precautions to be taken during the prediabetic stage can prevent many possible complications.

Qualitative and quantitative evaluation of diabetic choroidopathy using ultra-widefield indocyanine green angiography

To investigate angiographic characteristic features of diabetic choroidopathy, as well as choroidal vascular density (CVD) and fractal dimension (CFD) in diabetic eyes and controls using ultra-widefield (UWF) indocyanine green angiography (ICGA). All patients underwent UWF fluorescein angiography and ICGA. Using imageJ software, CVD and CFD was analyzed. SFCT was assessed using spectral-domain optical coherence tomography. The image parameters were compared based on the DR stage and the presence of diabetic macular edema (DME). One-hundred six eyes from 63 patients (59.11 ± 16.31 years; male [%]: 23 [36.5%]) were included in the DM group, and 40 eyes from 22 subjects were included in the control group. The DM group had a mean age of 59.11 ± 16.31 years and a mean HbA1c percentage of 7.72 ± 1.28%. The most common ICGA findings of DC were choroidal hyperpermeability (57.5%), hypofluorescent spots (48.1%). Salt and pepper pattern (19.8%), inverted inflow phenomenon (3.8%), choroidal arterial tortuosity (24.5%), and late choroidal non-perfusion (6.6%) were more common in advanced DR. The CVD, CFD, and SFCT increased as the DR severity progressed. The DME group had a significantly higher CFD and SFCT than the non-DME group (P < 0.001 and P = 0.019, respectively). The qualitative and quantitative UWF ICGA image analysis revealed that choroidal blood vessels became dilated, complex, and hyperpermeable as the DR progressed. These features of diabetic choroidopathy (DC) were more severe in eyes with DME than the non-DME eyes.

Visualization of erythrocyte stasis in the living human eye in health and disease

Blood cells trapped in stasis have been reported within the microcirculation, but their relevance to health and disease has not been established. In this study, we introduce an in vivo imaging approach that reveals the presence of a previously-unknown pool of erythrocytes in stasis, located within capillary segments of the CNS, and present in 100% of subjects imaged. These results provide a key insight that blood cells pause as they travel through the choroidal microvasculature, a vascular structure that boasts the highest blood flow of any tissue in the body. Demonstration of clinical utility using deep learning reveals that erythrocyte stasis is altered in glaucoma, indicating the possibility of more widespread changes in choroidal microvascular than previously realized. The ability to monitor the choroidal microvasculature at the single cell level may lead to novel strategies for tracking microvascular health in glaucoma, age-related macular degeneration, and other neurodegenerative diseases.

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.

Changes in ocular pulse amplitude and posterior ocular structure parameters in type 1 diabetic children without diabetic retinopathy

Background:

It is important to determine changes in posterior ocular structures in the early period before retinopathy develops in pediatric patients with type 1 diabetes mellitus (DM).

Objective:

To evaluate inner plexiform layer (IPL), ganglion cell layer (GCL), and retinal nerve fiber layer (RNFL) thicknesses, as well as the relationship between choroidal thickness (CT) and ocular pulse amplitude (OPA) in type 1 diabetic children without diabetic retinopathy (DR).

Design:

A prospective observational study.

Methods:

Group 1 ( n = 44) consisted of pediatric patients with type 1 DM without DR, and Group 2 ( n = 65) of pediatric control subjects. Both intraocular pressure (IOP) and OPA were measured using a dynamic contour tonometer. CT, IPL, GCL, and RNFL were all measured using spectral domain optical coherence tomography (OCT).

Results:

The mean IOP and OPA values were 16.67 ± 2.34 and 1.85 ± 0.34, respectively, in group 1, and 15.14 ± 2.17 and 1.65 ± 0.25 in Group 2 ( p = 0.001 for both). The mean subfoveal CT value was 294.30 ± 67.61 μm in group 1 and 394.42 ± 69.65 μm in Group 2 ( p < 0.001). The mean GCL and RNFL values were 1.09 ± 0.11 and 96.46 ± 11.69, respectively, in group 1, and 1.14 ± 0.09 and 101.73 ± 9.33 in Group 2 ( p = 0.005 and p = 0.008, respectively).

Conclusions:

IOP and OPA values were higher, and CT, GCL, and RNFL values were lower in children with type 1 DM during the early stages than in the healthy control group. These findings suggest that CT may be a marker of retinal involvement in children with type 1 DM without DR.

Resistive index of ophthalmic artery as an imaging biomarker of hypertension-related vascular and kidney damage

Aim: Resistive index of ophthalmic artery (RI-OA) is associated with atherosclerotic diseases. The aim of this study was to evaluate the association of RI-OA and hypertension-related vascular and kidney damage. Materials and methods: Two-hundred and eighty hypertensive patients underwent evaluation of RI-OA, carotid atherosclerosis and level of 24 h albuminuria. Results: Albuminuria and carotid atherosclerosis were positively associated with RI-OA independently of other cardiovascular risk factors. Receiver-operating characteristic curve analysis allowed us to calculate a cut-off value of RI-OA >0.625, which would be suspicious about the existence of atherosclerotic disease. Conclusion: The ophthalmic vascular circulation allows to study connections between macro- and microcirculation in vivo. RI-OA could be a useful marker for a better stratification of the risk of developing kidney and cardiovascular disease.

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.

Retinal Microcirculation Alterations in Microalbuminuric Diabetic Patients With and Without Retinopathy

PURPOSE

To investigate the effect of microalbuminuria (MA) on superficial vessel density (SVD), deep vessel density (DVD), and choriocapillaris vessel density (CVD) in type-2 diabetic patients.

METHODS

Twenty patients without diabetic retinopathy (DR) and MA (group 1), 20 patients without DR but with MA (group 2) and 30 patients with mild DR and MA (group 3) were enrolled in this prospective and cross-sectional study. SVD, DVD, and CVD of all patients were screened with optical coherence tomography angiography (OCTA). The relationships between these values and age, diabetes duration and metabolic parameters were also evaluated.

RESULTS

The whole macular SVD value was 50.15 ± 4.52 in group 1 and 47.81 ± 4.12 in group 2 (p = .04). The whole macular DVD value was 47.66 ± 2.76 in group 1, 44.37 ± 3.39 in group 3 (p = .02). Parafoveal DVD value was 52.58 ± 3.47 in group 1, 51.84 ± 2.23 in group 2, and 49.23 ± 3.38 in group 3 (p G1&3 = .001, p G2&3 = .02). Perifoveal DVD value was 47.92 ± 3.30 in group 1, 43.96 ± 4.19 in group 2, and 42.85 ± 2.98 in group 3 (p G1&2 = .02 and p G1&3 < .001). There were inverse correlations between diabetes duration, urea, creatinine, albumin, urinary sodium and some DVD values (p < .05, for all). Also, there were inverse correlations between parafoveal and perifoveal DVD values and MA (p = .002 and p = .031). Additionally, inverse correlations were determined between diabetes duration, creatinine, urea, serum Na and some CVD values (p < .05 for all).Conclusion: Decreased SVD and DVD values measured by OCTA in type-2 diabetic patients, whether they have mild DR or not, may be associated with MA causing early retinal microvascular changes.

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.

The effect of changes in cardiovascular activity on corneal biomechanics and pulsation in rabbits

The aim was to assess the relationships between cardiovascular activity, corneal pulse characteristics, and corneal biomechanics in rabbits. Seventeen rabbits were randomly assigned to one of two anesthetic regimens to induce differences in arterial blood pressure and heart rate. Experimental protocol included measuring blood flow parameters in the ophthalmic artery by color Doppler imaging, corneal biomechanical parameters using a non-contact tonometer Corvis ST, and the corneal pulse (CP) signal using a non-contact ultrasonic technique. Statistically significantly lower mean values of normalized amplitudes of higher CP harmonics and changes in eight of the twelve corneal biomechanical parameters were observed in the rabbit group with lower arterial blood pressure and higher heart rate, intraocular pressure, and resistive index. The results of partial correlations showed that the CP signal energy and amplitude of its first harmonic correlate with the resistive index, diastolic and mean arterial pressures, whereas no statistically significant correlation was found between any of the CP parameters and intraocular pressure. Our pilot study indicates, for the first time, that non-contact and continuous measuring of corneal pulse allows indirectly assessing changes in cardiovascular activity when the confounding effect of intraocular pressure is eliminated.

Assessment of Diabetic Retinopathy Vascular Density Maps

Purpose

Optical coherence tomography (OCT) and OCTA were used for qualitative and quantitative assessment of retinal vascular density in superficial capillary plexus, deep capillary plexus, foveal avascular zone, and choroidal vascular density map.

Patients and Methods

This study included 64 eyes. Diabetics and control groups were recruited from an internal medicine clinic at Misr University for Science and Technology Hospital and asked to participate in this study. This study was designed as an observational and cross-sectional study in the period from 8/2018 to 8/2019.

Results

There was a decrease in choroidal vascular density in diabetic patients. There was a decrease in retinal thickness in diabetic patients and there were no significant differences in the retinal thickness between control subjects and patients with non-diabetic retinopathy (NDR).

Conclusion

Our study suggests that OCTA can identify preclinical DR before the manifestation of clinically apparent retinopathy. Our findings also highlight the potential role of OCTA in monitoring and quantifying retinal vascular alterations in diabetics.

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.

Identifying central serous chorioretinopathy biomarkers in coexisting diabetic retinopathy: a multimodal imaging study

BACKGROUND

To describe clinical and imaging characteristics of patients presenting with diabetic retinopathy (DR) with coexisting acute or chronic central serous chorioretinopathy (CSCR).

METHODS

This was a cross-sectional study which included 54 eyes of 27 patients with coexisting DR and CSCR. Demographic details, prior history of laser, best-corrected visual acuity (BCVA), central macular thickness (CMT), height of neurosensory detachment (NSD), subfoveal choroidal thickness (SFCT), subfoveal large choroidal vessel layer thickness (SF-LCVT), fluorescein angiography and indocyanine green angiography features were recorded. Subanalysis was done for patients with unilateral CSCR. Data was evaluated using Student t-test for quantitative data and χ² test for qualitative data. CSCR between different grades of DR was analysed using analysis of variance.

RESULTS

Prevalence of coexistent CSCR in eyes with DR was 0.4%. Mean age was 53.96±8.79 years, with 25 males. Mean CMT was 349.2±258 μm. Mean SFCT and SF- LCVT of 38 eyes were 376.40±86 μm and 178.80±62.8 μm, respectively. Fifteen eyes had centre involving diabetic macular oedema. Subanalysis of patients with unilateral CSCR showed that the loss of inner segment-outer segment (IS-OS) integrity (p=0.001), photoreceptor footplates at the NSD roof (p=0.001) on optical coherence tomography and dilated choroidal vessels (p=0.05) on indocyanine green angiography were found more often in the CSCR eyes compared with their fellow eyes. Features of CSCR among the different grades of DR were not significantly different between the groups.

CONCLUSION

Our study describes features of a unique subset of patients presenting with coexistent DR and CSCR. Such coexistent nature needs special attention by the clinicians as this may change the treatment approach and alter outcomes.

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.

Differences in macular capillary parameters between healthy black and white subjects with Optical Coherence Tomography Angiography (OCTA)

Purpose

To investigate if there are differences in macular capillaries between black and white subjects using optical coherence tomography angiography (OCTA) and identify potential factors underlying the epidemiologically-based higher vulnerability of black populations to diabetic retinopathy (DR).

Methods

This prospective, observational cross-sectional study included 93 eyes of 47 healthy subjects with no medical history and ocular history who self-identified as black or white and were matched for age, sex, refractive error, and image quality. Subjects underwent OCTA imaging (RTVue-XR Avanti) of the superficial (SCP) and deep (DCP) capillary plexuses and choriocapillaris. AngioAnalytics was used to analyze vessel density (VD) and choriocapillaris % blood flow area (BFA) in the 1mm-diameter fovea, parafovea, and 3mm-diameter circular area including the fovea and parafovea (3x3mm image). Foveal avascular zone (FAZ) was also analyzed. Linear mixed models were used to evaluate for differences between the study groups.

Results

Compared to the white subjects in this study, black subjects were found to have: lower foveal VD in the SCP (p<0.05); lower VD in the parafovea and in the 3x3mm image in the DCP (p<0.05); larger FAZ in SCP and DCP (p<0.05); and decreased choriocapillary BFA in the area underlying the fovea, parafovea, and 3x3mm image (p<0.05).

Conclusion

In our study, our black subjects had decreased macular capillary vasculature compared to matched white subjects, even in early adulthood and the absence of any systemic or ocular conditions. To our knowledge, this is the first report showing that retinal and choriocapillary vascular differences may contribute to racial disparities in vulnerability to DR.

Relationship Between the Parameters of Corneal and Fundus Pulse Signals Acquired With a Combined Ultrasound and Laser Interferometry Technique

Purpose

To estimate the relationship between the characteristics of the corneal pulse (CP) signal and those of the fundus pulse (FP) signal measured with a combined noncontact ultrasonic and laser interferometry technique in healthy subjects.

Methods

Twenty-two healthy subjects participated in experiments that included measurements of intraocular pressure, ocular pulse amplitude, ocular biometry, blood pressure, and heart rate. Additionally, simultaneous recordings of CP and FP signals were acquired with a noncontact ultrasonic device combined with laser interferometry. Subsequently, ocular perfusion pressure (OPP) and the time and spectral parameters of CP and FP signals were computed. A system model was proposed to relate the FP signal to the CP signal.

Results

The system model revealed that the eye globe transfers information between signals of the posterior and anterior eye, relatively amplifying higher spectral harmonics. The amplitude of the second CP harmonic is predicted by FP_RMS and OPP (R² = 0.468, P = 0.002). Partial correlation analysis showed that the CP signal parameters are statistically significantly correlated with those of the FP signal and OPP, after correcting for age and sex.

Conclusions

The eye globe can be viewed as a high pass filter, in which the CP characteristic changes in relation to the fundus pulsation. The FP signal and OPP have an impact on the variations of the CP signal morphology.

Translational Relevance

Investigation of differences between the characteristics of the anterior and posterior tissue movements is a promising method for evaluating the role of circulatory and biomechanical components in the pathophysiology of ocular diseases.

Usefulness of color Doppler imaging of orbital arteries in young hypertensive patients

Color Doppler imaging (CDI) is an established method for investigating ocular blood flow characteristics, and several blood flow parameters can be obtained from the velocity wave. This study evaluated CDI parameters in hypertensive subjects by measuring flow velocities, resistive index, and the pulsatility index of ocular arteries. One hundred young hypertensive patients and 50 age- and gender-matched healthy controls were recruited for the study. CDI parameters of the ophthalmic artery, central retinal artery, and posterior ciliary artery were measured in all subjects. Doppler index cutoff points were calculated using area under the curve with 95% confidence intervals. Results showed that Doppler parameters were significantly higher in subjects diagnosed with hypertension in the young compared to controls.

Detection of Subclinical Diabetic Retinopathy by Fine Structure Analysis of Retinal Images

Background and Objective

Diabetic retinopathy (DR) is a major complication of diabetes and the leading cause of blindness among US working-age adults. Detection of subclinical DR is important for disease monitoring and prevention of damage to the retina before occurrence of vision loss. The purpose of this retrospective study is to describe an automated method for discrimination of subclinical DR using fine structure analysis of retinal images.

Methods

Discrimination between nondiabetic control (NC; N = 16) and diabetic without clinical retinopathy (NDR; N = 17) subjects was performed using ordinary least squares regression and Fisher's linear discriminant analysis. A human observer also performed the discrimination by visual inspection of the images.

Results

The discrimination rate for subclinical DR was 88% using the automated method and higher than the rate obtained by a human observer which was 45%.

Conclusions

The method provides sensitive and rapid analysis of retinal images and could be useful in detecting subclinical DR.

SIGNIFICANT REDUCTION OF BOTH PERIPAPILLARY AND SUBFOVEAL CHOROIDAL THICKNESS AFTER PANRETINAL PHOTOCOAGULATION IN PATIENTS WITH TYPE 2 DIABETES

PURPOSE

To evaluate changes in peripapillary choroidal thickness (PCT) and subfoveal choroidal thickness (SFCT) after panretinal photocoagulation (PRP) for diabetic retinopathy.

METHODS

This retrospective interventional study included 59 treatment-naive eyes of 33 patients who underwent PRP and completed ≥12 months of follow-up. Peripapillary choroidal thickness and SFCT were measured at baseline and 1, 3, 6, and 12 months post-PRP. Differences between baseline and 12 months (ΔSFCT and ΔPCT) and percentage changes (ΔSFCT or ΔPCT/baseline × 100%) were determined.

RESULTS

Mean SFCT was 287.7 ± 76.7 μm (139.0-469.0 μm) at baseline and 225.8 ± 62.0 μm (102.5-379.5 μm) 12 months post-PRP (P < 0.001). Mean PCT was 161.2 ± 16.5 μm (75.3-308.1 μm) at baseline and 128.4 ± 41.8 μm (73.0-212.9 μm) 12 months post-PRP (P < 0.001). ΔSFCT was -61.3 ± 28.7 μm (-139.5 to -17.0 μm), and %SFCT was 21.2 ± 7.2% (6.8% to 36.1%). ΔPCT was -36.4 ± 23.2 μm (-149.1 to 5.4 μm), and %PCT was 22.4 ± 12.0% (2.5% to 62.6%). Diabetic retinopathy severity was the only factor significantly correlated with %SFCT (β = 0.500, P = 0.004) and %PCT (β = 0.152, P = 0.024).

CONCLUSION

Both PCT and SFCT reduced significantly after PRP. Diabetic retinopathy severity was significantly correlated with post-PRP changes of peripapillary and SFCT.

Quantitative analysis of retinal and choroid capillary ischaemia using optical coherence tomography angiography in type 2 diabetes

PURPOSE

To perform a quantitative analysis of retinal and choroid capillary ischaemia in diabetic patients by using optical coherence tomography angiography (OCTA).

METHODS

A total of 97 type 2 diabetic patients and 48 controls were included in this cross-sectional study. Diabetic patients without diabetic retinopathy (DR) were categorized as no DR (NDR) group; DR was classified into mild non-proliferative diabetic retinopathy (NPDR), moderate NPDR, severe NPDR and proliferative diabetic retinopathy (PDR). Quantitative parameters included foveal and parafoveal vascular density (VD) in superficial, deep and choroid capillary plexus (SCP, DCP and CCP), and foveal flow area in CCP. Stepwise comparisons between groups were performed in the adjacent stages.

RESULTS

Diabetic patients had significantly lower flow area in CCP and VD in all three layers compared with controls. In NDR group, foveal flow area in CCP significantly decreased compared with controls. In mild NPDR, parafoveal VD significantly decreased in all three layers compared with NDR, especially in temporal and nasal areas. In moderate NPDR, VD reduction extended to the inferior area in SCP and DCP compared with mild NPDR. In severe NPDR, progressive losses of VD were presented in all layers compared with moderate NDPR. In PDR, the superior VD in SCP significantly increased compared with severe NPDR.

CONCLUSION

In diabetic patients, the microvascular ischaemia originated in choroid layer and extended inward affecting the deep and superficial layer. OCTA can serve as a reliable method for early detection and to monitor progressions in diabetic retinopathy.

Diabetic choroidopathy

Early histopathological studies of diabetic choroids demonstrated loss of choriocapillaris (CC), tortuous blood vessels, microaneurysms, drusenoid deposits on Bruchs membrane, and choroidal neovascularization. The preponderance of histopathological changes were at and beyond equator. Studies from my lab suggest that diabetic choroidopathy is an inflammatory disease in that leukocyte adhesion molecules are elevated in the choroidal vasculature and polymorphonuclear neutrophils are often associated with sites of vascular loss. Modern imaging techniques demonstrate that blood flow is reduced in subfoveal choroidal vasculature. Angiography has shown areas of hypofluorescence and late filling that probably represent areas of vascular loss and/or compromise. Perhaps, as a result of vascular insufficiency, the choroid appears to thin in DC unless macular edema is present. Enhanced depth imaging (EDI-SD) OCT and swept source (SS) OCT have documented the tortuosity and loss in intermediate and large blood vessels in Sattler's and Haller's layer seen previously with histological techniques. The risk factors for DC include diabetic retinopathy, degree of diabetic control, and the treatment regimen. In the future, OCT angiography could be used to document loss of CC. Because most of the measurement and imaging are in the posterior pole, the severity of DC may be underappreciated in the published accounts of DC assessed with imaging techniques. However, it is now possible to document DC and quantify these changes clinically. This suggests that DC should be evaluated in future clinical trials of drugs targeting DR because vascular changes similar to those in DR are occurring in DC.

Choroidal thickness alterations in diabetic nephropathy patients with early or no diabetic retinopathy

PURPOSE

To assess changes in choroidal thickness (CT) in diabetes patients with and without diabetic nephropathy using enhanced depth imaging spectral domain optical coherence tomography (EDI-OCT).

METHODS

Thirty-five type 2 diabetes patients with a diagnosis of diabetic nephropathy (DNP) in nephrology department and 35 type 2 diabetes patients without nephropathy (non-DNP) were included in our prospective study consecutively. The control group comprised 34 healthy individuals. CT measurements were recorded under the fovea and at 1500 µm from the foveal center in the nasal and temporal sides. The study parameters also included age, refractive error, axial length, intraocular pressure, HbA1c, glomerular filtration rate and proteinuria amount.

RESULTS

The subfoveal, temporal and nasal choroidal thickness was noted to be thinner in patients with DNP compared with non-DNP and normal subjects (p < 0.05). However, CT measurements did not show any difference between the healthy and non-DNP group.

CONCLUSION

CT decreases significantly in diabetic patients when diabetic nephropathy accompanies diabetes mellitus.

Age-related macular degeneration in a South Indian population, with and without diabetes

PurposeTo elucidate the prevalence and risk factors of age-related macular degeneration (AMD) in people with diabetes.MethodsOf the 5495 subjects ≥60 years of age recruited in the population-based study in south India, 4791 subjects with gradable images on 30° three-field retinal photographs were analyzed. AMD and diabetic retinopathy (DR) were graded based on the International ARM Epidemiological Study Group classification and International Clinical Diabetic Retinopathy Disease Severity Scale, respectively. All subjects underwent a detailed history, physical examination, and a comprehensive ocular examination.ResultsOf the 4791 subjects, 1256 had diabetes. In those with diabetes, 166 (13.2%) had DR: of which, 9.6% had AMD. Of those with diabetes but no DR, 15.6% had AMD. Presence of DR (OR=0.57, 95% CI: 0.33-0.99, P=0.046) was a protective factor for AMD in diabetes. When adjusted for potential confounding factors, those with AMD and diabetes were from urban areas (OR=1.65, 95% CI: 1.09-2.49, P=0.018), had raised systolic blood pressure (OR=1.02, 95% CI: 1.00-1.03, P=0.01), higher BMI (OR=1.06, 95% CI: 1.02-1.10, P=0.005), and higher serum triglycerides (OR=1.00, 95% CI: 1.00-1.01, P=0.011). A higher level of high-density lipoprotein (HDL) (OR=0.98, 95% CI: 0.96-0.99, P=0.038) was a protective factor for AMD in subjects with diabetes.ConclusionsThe presence of DR and higher serum HDL are protective factors whereas obesity and higher systolic blood pressure are risk factors for AMD in subjects with diabetes.

Relationship between glycosylated hemoglobin A1c and ocular circulation by laser speckle flowgraphy in patients with/without diabetes mellitus

PURPOSE

To determine whether there are significant correlations between the hemodynamics of the optic nerve head (ONH) and choroid as shown by laser speckle flowgraphy (LSFG) and the fasting blood sugar (FBS) and HbA1c level in patients with/without diabetes mellitus (DM).

METHODS

We analyzed 196 consecutive patients (151 men, 45 women). The pulse waveform analysis parameters of the mean blur rate (MBR), blowout score (BOS) and blowout time (BOT) in the ONH and choroid were evaluated. We used a multiple regression analysis to determine the independent factors for the LSFG parameters that are significantly correlated with FBS or HbA1c. We evaluated the relationship between the LSFG parameters FBS and HbA1c obtained from the 147 non-DM patients.

RESULTS

The multiple regression analysis revealed that hematocrit and HbA1c were factors contributing independently to the choroid MBR. The age, gender, pulse pressure, heart rate, spherical refraction and HbA1c were identified as factors contributing independently to the BOS in the ONH. The multiple regression analysis indicated that age, height, pulse pressure, heart rate and HbA1c were factors contributing independently to the BOS in the choroid. A Pearson's correlation analysis showed that the BOT values in the ONH and choroid were significantly correlated with the HbA1c in the non-DM patients.

CONCLUSION

Our results confirmed that HbA1c, even within the normal range, affected the blood flow in the ONH and choroid. LSFG may be a useful method to detect abnormalities of asymptomatic ocular circulation.

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

PURPOSE

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.

Subfoveal choroidal thickness in eyes with diabetic macular oedema using swept source optical coherence tomography

PURPOSE

To compare subfoveal choroidal thickness (GCSF) in patients with diabetic macular oedema (DMO) and healthy subjects using swept source optical coherence tomography (SS-OCT).

METHOD

Cross-sectional study including 50 eyes of 36 patients with DMO, and 47 eyes of 34 patients as a control group. GCSF was measured in both groups, analysing between the eyes with DMO according to the type of oedema (predominantly cystic or diffuse).

RESULTS

The study groups were homogeneous in terms of mean age (63.4 years for DMO and 62.65 years for controls; P=.36) and the mean axial length (23.21mm for DME and 23.53mm for controls; P=.06). A statistically significant reduction in the eye with DME GCSF compared to controls (P=.041, 222.9 vs. 192.82 μm) was observed. No statistically significant differences were observed in the eyes with DMO with a predominantly cystic pattern and diffuse oedema (P=.13, 178.68 vs. 205.7 μm).

CONCLUSION

The GCSF in patients with DMO could be reduced. Future studies are needed to confirm these preliminary results.

Diabetic choroidopathy: a review of the current literature

Diabetic retinopathy is an increasingly prevalent disease, and a leading contributor to the burden of all-cause blindness worldwide. In addition to retinal changes, choroidal abnormalities are common in patients with diabetes. The first studies concerning this vascular structure were based on histologic, indocyanine angiography and laser Doppler flowmetry techniques, but the development of new optical coherence tomography (OCT) technologies and imaging software for enhanced depth imaging (EDI)-OCT in recent years has made it possible to provide more detailed images of the choroidal anatomy and topography.In diabetic patients, several choroidal changes have been described in the literature throughout the years; the recent focus is choroidal thickness, which is significantly different from that in healthy patients. However, understanding choroidal manifestations of diabetic eye disease remains a real challenge, and this gap is hindering efforts towards better defining choroidal evaluation as a predictive factor for disease evolution and treatment response.This review aims to summarize the recent literature concerning changes in choroidal structure in diabetic patients, the relationship to diabetic retinal disease progression, and finally, the current and potential application of the measurement of variations in choroidal thickness for patient management.

Evaluation of resistive index using color Doppler imaging of orbital arteries in geriatric patients with hypertension

Background and Aim:

Resistive index (RI) is an indirect measurement of blood flow resistance that can be used to evaluate vascular damage in ophthalmologic disease. The purpose of this study was to evaluate the association between RI values of orbital arteries using the color Doppler imaging (CDI) in geriatric hypertensive patients with or without retinopathy.

Setting and Design:

Designed as a cross-sectional study.

Materials and Methods:

We evaluated 60 geriatric patients with hypertension (Group 1) and 30 healthy subjects (Group 2). Further, the patients with hypertension were grouped into two: Group 1a consisted of patients with retinopathy (n = 30), and group 1b consisted of patients without retinopathy (n = 30). The mean RI values of ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured using CDI.

Results:

Compared to group 2, group 1 had significantly higher mean resistive index of PCA levels (P = 0.017), whereas there were no statistical difference in mean resistive indexes of OA and CRA (both P > 0.05). Besides, there were no statistical difference in mean resistive indexes of OA, CRA, and PCA between the group 1a and group 1b (P > 0.05 for all). Mean resistive indexes of OA, CRA, and PCA were significantly correlated with the duration of hypertension (r = 0.268, P = 0.038; r = 0.315, P = 0.014; r = 0.324, P = 0.012, respectively).

Conclusions:

Our study indicates that RI might be a useful marker for the ocular hemodynamic of retinal vessels, provides morphologic and vascular information in hypertension and hypertensive retinopathy.

Vascular Dysfunction in Diabetes and Glaucoma: A Complex Relationship Reviewed

Open-angle glaucoma (OAG) is a multifactorial disease characterized by progressive retinal ganglion cell death and visual field loss. Intraocular pressure, ocular perfusion pressure, and systemic vascular irregularities have all been identified as contributing factors for glaucoma onset and progression. Focal and systemic vascular abnormalities have also been well documented in diabetic patients. The relationship between diabetes mellitus and OAG remains enigmatic in the literature. As the pathogenesis of both diabetes mellitus and OAG involves compromised vascular regulation, this review was undertaken to further investigate their precise relationship. A literature review of published population-based studies was performed, with a focus on studies regarding blood flow abnormalities. Although current studies support the role of vascular contributions to both diseases, the association between glaucoma and diabetes yields contrasting results.

Effect of intravitreal bevacizumab on retrobulbar blood flow of patients with diabetic macular edema

PURPOSE

To determine the effect of intravitreal bevacizumab on retrobulbar blood flow of patients with diabetic macular edema.

METHODS

Peak systolic velocity, end-diastolic velocity, resistance, and pulsatility indices of central retinal artery (CRA), nasal posterior ciliary artery (NPCA), temporal posterior ciliary artery (TPCA), and ophthalmic artery (OA) were assessed by color Doppler ultrasonography in injected and uninjected eyes of 37 patients at baseline and at day 1 and day 7 after the injection.

RESULTS

At day 1 after the injection, peak systolic and end diastolic velocities of the CRA and NPCA in the injected eyes and peak systolic velocity of NPCA in the uninjected eyes decreased significantly (p&lt;0.05, p = 0.025, respectively). Peak systolic and end diastolic velocities were not significantly different in the injected and uninjected eyes at day 7 after the injection (p&gt;0.05). In the injected eyes, there was no significant change in resistance and pulsatility indices (p&gt;0.05), but a decrease in resistance index of NPCA and resistance and pulsatility indices of TPCA occurred in uninjected eyes at day 7 after the injection (p = 0.016, p = 0.023, and p = 0.025, respectively).

CONCLUSIONS

Intravitreal bevacizumab affects retrobulbar blood flow in injected and uninjected eyes of patients with diabetic macular edema.

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.

Analysis of morphological features and vascular layers of choroid in diabetic retinopathy using spectral-domain optical coherence tomography

IMPORTANCE

Diabetic retinopathy (DR) is characterized by microaneurysms, capillary nonperfusion, and ischemia within the retina, ultimately leading to neovascularization and/or macular edema. Evidence suggests that choroidal angiopathy may coexist with retinal vascular damage. Recent advances in spectral-domain optical coherence tomography (SD-OCT) permit an efficient visualization of the choroid.

OBJECTIVE

To analyze the morphological features and vascular layers of the choroid in patients with DR using SD-OCT.

DESIGN

A cross-sectional retrospective review identified patients with DR and healthy (control) subjects who underwent 1-line raster scanning from February 1, 2010, through June 30, 2012. Patients were classified into the following 3 groups: nonproliferative DR without macular edema (9 eyes), proliferative DR without macular edema (PDR) (10 eyes), and diabetic macular edema (DME) (14 eyes). Two independent raters experienced in analyzing OCT images evaluated the morphological features and vasculature of the choroid.

SETTING

New England Eye Center.

PARTICIPANTS

Thirty-three eyes of 33 patients with DR and 24 eyes of 24 controls.

EXPOSURE

Diabetic retinopathy.

MAIN OUTCOME AND MEASURE

Choroidal morphological features and vasculature analysis.

RESULTS

The choroidoscleral interface had an irregular contour in 8 of 9 eyes with nonproliferative DR (89%), 9 of 10 eyes with PDR (90%), and 13 of 14 eyes with DME (93%) compared with 0 of 24 controls. The thickest point of the choroid was displaced from under the fovea, and focal choroidal thinning was observed in eyes with DR. Mean subfoveal choroidal thickness and mean subfoveal medium choroidal vessel layer and choriocapillaris layer thickness were significantly reduced in eyes with PDR (P < .05) and DME (P < .05) compared with controls.

CONCLUSIONS AND RELEVANCE

Choroidal morphological features are altered in patients with moderate to severe DR. The subfoveal choroidal thickness and the subfoveal medium choroidal vessel layer and choriocapillaris layer thicknesses are significantly reduced in patients with PDR and DME. To our knowledge, this is the first study to analyze the morphological features and vasculature of the choroid in DR using SD-OCT. These findings may be clinically useful in predicting the progression of DR.

Can optical coherence tomography replace fluorescein angiography in detection of ischemic diabetic maculopathy?

Background

We studied the association between (1) the retinal thickness, volume and structure assessed by optical coherence tomography (OCT), and (2) vascular changes around the fovea in FA to define the role of these methods in the detection of ischemic diabetic maculopathy.

Methods

This retrospective observational study included 51 eyes of 51 patients with severe non-proliferative and proliferative diabetic retinopathy, considering that they present advanced ischemic retinal changes. Based on the clinical examination and presence of leakage on FA, patients with clinically significant macular edema were excluded.

On FA, foveal avascular zone (FAZ) corresponds to capillary loss and reflects ischemic processes. Its outline and size were assessed according to the ETDRS standards. Patients were divided in two groups according to the severity of damage of the FAZ outline: ≤ grade 2 (n = 28) and ≥ grade 3 (n = 23).

As we expected ischemia-related damage, SD-OCT images were evaluated for retinal structure, volume, total thickness with division into the outer and inner retina (to assess the influence of two, non-overlapping blood sources) and ganglion cell layer thickness.

Results

The comparisons revealed that at least currently with described methods:

1. There is no significant association between FAZ outline and retinal volume, total thickness, and thickness of the outer and inner retina and ganglion cell layer.

2. There is no significant association between FAZ outline and following retinal structure characteristics: continuity of the external limiting membrane and inner segment/outer segment junction, and identification of the inner/outer retina boundary.

3. The identification of ganglion cell layer boundaries was significantly more difficult in more advanced FAZ outline grades.

4. FAZ size is not correlated with the retinal thickness and volume.

Conclusions

In patients with severe non-proliferative and proliferative diabetic retinopathy, it is not possible to predict FAZ outline/size based solely on the measurements assessing volume and thickness or retinal structure evaluation on OCT. Consequently, at present OCT cannot replace FA in the detection of ischemic diabetic maculopathy.

Calculation of central retinal artery diameters from non-invasive ocular haemodynamic measurements in type 1 diabetes patients

PURPOSE

The aim of the study was to compare the diameter of the central retinal artery (CRA) between patients with diabetes mellitus and healthy subjects in vivo. CRA diameters were calculated from retinal haemodynamic parameters measured with noninvasive measurement techniques.

METHODS

Sixteen patients with type 1 diabetes with no or mild diabetic retinopathy and 16 age-matched healthy controls were included in this study. Total retinal blood flow was assessed by combining bidirectional laser Doppler velocimetry in all veins entering the optic disc with measurements of retinal vessel diameters using a Dynamic Vessel Analyser. Blood flow velocity in the CRA was measured with colour Doppler imaging (CDI). The diameter of the CRA in the optic nerve was then calculated for each subject using the individual ocular haemodynamic data.

RESULTS

Calculated CRA diameters were significantly larger in patients with diabetes (180 ± 13 μm) compared with healthy controls (166 ± 10 μm, p = 0.001). No significant differences were found in retinal blood flow, retinal artery or vein diameters or mean flow velocity of the CRA.

CONCLUSION

The data of the present study show increased calculated CRA diameter in patients with type 1 diabetes with no or mild retinopathy. Blood flow velocity measurements in retrobulbar vessels using CDI need to be interpreted with caution in terms of retinal blood flow, because no information about vessel diameters is obtained by this technique.

Perivascular mural cells of the mouse choroid demonstrate morphological diversity that is correlated to vasoregulatory function

Objective

Perivascular mural cells of the choroid have been implicated in physiological functioning as well as in retinal disease pathogenesis. However details regarding their form and function are not well understood. We aim to characterize choroidal mural cells in the adult mouse choroid in terms of their distribution and morphology, and correlate these to their contractile behavior.

Methods

Sclerochoroidal flat-mounted explants were prepared from albino transgenic mice in which the α-smooth muscle actin (α-SMA) promoter drives the expression of green fluorescent protein (GFP). α-SMA-expressing smooth muscle cells and pericytes in the living choroid were thereby rendered fluorescent and imaged with confocal microscopy and live-cell imaging in situ.

Results

Choroidal perivascular mural cells demonstrate significant diversity in terms of their distribution and morphology at different levels of the vasculature. They range from densely-packed circumferentially-oriented cells that provide complete vascular coverage in primary arteries to widely-spaced stellate-shaped cells that are distributed sparsely over terminal arterioles. Mural cells at each level are immunopositive for contractile proteins α-SMA and desmin and demonstrate vasoconstrictory contractile movements in response to endothelin-1 and the calcium ionophore, A23187, and vasodilation in response to the calcium chelator, BAPTA. The prominence of vasoregulatory contractile responses varies with mural cell morphology and density, and is greater in vessels with dense coverage of mural cells with circumferential cellular morphologies. In the choriocapillaris, pericytes demonstrate a sparse, horizontal distribution and are selectively distributed only to the scleral surface of the choriocapillaris.

Conclusions

Diversity and regional specialization of perivascular mural cells may subserve varying requirements for vasoregulation in the choroid. The model of the α-SMA-GFP transgenic albino mouse provides a useful and intact system for the morphological and functional study of choroidal mural cells.

Evaluation of resistive index by color Doppler imaging of orbital arteries in type II diabetes mellitus patients with microalbuminuria

OBJECTIVE

Resistive index (RI) is an indirect measurement of blood flow resistance that can be used to evaluate vascular damage in ophthalmologic diseases. The purpose of this study was to evaluate the association between RI values of orbital arteries by using the color Doppler imaging (CDI) in type II diabetes mellitus (DM) patients with microalbuminuria.

PATIENTS AND METHODS

We evaluated 91 type II DM patients with microalbuminuria and 27 healthy subjects. The DM patients with microalbuminuria were grouped into two: group 1 consisted of patients with retinopathy (n = 51) and group 2 consisted of patients without retinopathy (n = 40). Healthy subjects constituted group 3 (n = 27). The mean RI values of ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured using CDI.

RESULTS

Compared to diabetic group 2, group 1 had significantly higher mean RIs of OA, CRA, PCA, and HbA1c levels (p < 0.001 for all). Besides, there were no statistical differences in mean RIs of OA, CRA, and PCA between the control group and group 2 (p = 1.0; p = 0.44; p = 0.67, respectively). Mean RIs of OA and PCA were significantly correlated with age in group 1 (r = 0.549, p < 0.001; r = 0.407, p = 0.003, respectively). Mean RI of CRA was significantly correlated with the duration of diabetes and age in group 1 (r = 0.296, p = 0.035; r = 0.486, p < 0.001, respectively).

CONCLUSION

Our study indicates that RI might be a useful marker for early diagnosis and follow-up of diabetic retinopathy, and orbital RI assessment would be beneficial for diabetic patients with retinopathy.

Use of colour Doppler imaging in ocular blood flow research

The main objective of this report is to encourage consistent quality of testing and reporting within and between centres that use colour Doppler imaging (CDI) for assessment of retrobulbar blood flow. The intention of this review is to standardize methods in CDI assessment that are used widely, but not to exclude other approaches or additional tests that individual laboratories may choose or continue to use.

Ocular pulse amplitude and retrobulbar blood flow change in dipper and non-dipper individuals

PURPOSE

To evaluate ocular pulse amplitude (OPA), IOP values, and hemodynamic changes in the ophthalmic artery, central retinal artery, and short posterior ciliary artery in dipper and non-dipper patients.

METHODS

A total of 59 right eye measurements of healthy subjects with normotensive were included to the study. Ambulatory blood pressure (BP) monitoring measurement (ABPM), Doppler imaging, and OPA measurements were performed in the same day. The patients in which systolic BP decreased during the nocturnal time by 10% of the diurnal BP or more were called dippers. A patient whose nocturnal systolic BP fell by <10% or even rose was defined as non-dipper. Color Doppler imaging was used for blood flow velocity assessment of ophthalmic, central retinal, and posterior ciliary arteries. For each artery, peak systolic and end-diastolic velocities (PSV and EDV, respectively), resistive index (RI), and pulsalite index (PI) were automatically calculated by the machine. Mean IOP and OPA values were calculated after three consecutive measurements.

RESULTS

The mean OPA in non-dipper patients was significantly lower compared with that of dipper patients (P=0.011). There was no significant difference in IOP levels between groups. There was no significant difference in the PSV, EDV, RI, and PI in the ophthalmic, posterior ciliary, and central retinal arteries between the groups.

CONCLUSION

Our study demonstrated that OPA level in non-dippers is lower than dippers. This may give additional information about the effect of BP changes on OPA values.

Relationship between ocular pulse amplitude and systemic blood pressure measurements

PURPOSE

This study aimed to determine whether ocular pulse amplitude (OPA) measured with dynamic contour tonometry (DCT) is related to systemic blood pressure (BP) parameters.

METHODS

Blood pressure was measured continuously and simultaneously with OPA in one randomly selected eye in 29 healthy subjects. Systemic parameters of interest were: systolic and diastolic BPs and their difference (BP amplitude), and left ventricle ejection time (LVET; defined as the time between the diastolic trough and the incisural notch in the BP curve). In addition, the axial length (AL) of the eye was measured. Associations between OPA, AL and systemic cardiovascular parameters were analysed in a multivariate regression model.

RESULTS

Measurements of OPA ranged from 1.0 mmHg to 4.9 mmHg (mean 2.3 +/- 0.9 mmHg, median 1.9 mmHg). In a univariate analysis with one predictor at a time, means of intraocular pressure (IOP) (p = 0.008), AL (p = 0.046) and LVET (p = 0.037) were significantly correlated with OPA, whereas systolic and diastolic BPs and their amplitude were not. A multiple linear regression analysis showed that mean IOP (p < 0.005), AL (p = 0.01) and LVET (p = 0.002) all independently contributed to OPA.

CONCLUSIONS

The OPA readings measured with DCT in healthy subjects were not related to BP levels and amplitude. It seems that the OPA strongly depends on the time-course of the cardiac contraction. Regulating mechanisms in the carotid system as well as scleral rigidity may be responsible for dampening the direct effect of BP variations.

[Not Available]

The aim of the study was to determine whether the Heidelberg Retinal Flowmeter (HRF), a confocal scanning laser Doppler flowmeter, can measure choroidal blood flow in pig eyes.

An HRF was used to obtain flow maps from in vitro pig eyes under a range of perfusion flow rates (0 – 500 µL/min) under conditions in which only the choroid was perfused. In some cases choroidal blood flow was also measured simultaneously using a conventional fiberoptic based Laser Doppler Perfusion Monitor (LDPM) which used the same laser wavelength (780 nm). The relationship between perfusion flow, HRF measured flow and LDPM measured flow was determined. HRF flow maps were also obtained in vivo as a function of focal plane setting through the retina and choroid.

Across the range of perfusion flow rates through the isolated eyes there was a poor correlation with HRF measured choroidal flow and perfusion flow. In contrast, there was a strong linear relationship between perfusion flow and LDPM measured blood flow. Both in vitro and in vivo, no choroidal vessels could be visualised in the HRF flow maps, even when the focal plane was in the choroid.

The HRF is unable to measure choroidal blood flow in pig eyes. This is not due to an inability of the 780 nm laser to penetrate into the choroid or due to red blood cell velocities in the choroid being higher than the measurement range of the instrument.

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.