Changes In Caliber Of Vessels Research Articles

Exploring the Relation Between Peripapillary Retinal Vessel Caliber and Visual Field Defects in Primary Open-Angle Glaucoma.

Background Primary open-angle glaucoma (POAG) is a progressive optic neuropathy characterized by loss of retinal ganglion cells, optic nerve head changes, and visual field defects. Vascular factors, alongside intraocular pressure, play a crucial role in POAG pathogenesis, and this study aims to explore the relationship between retinal vessel caliber and visual field defects in POAG patients. Purpose To evaluate the association between retinal vessel calibers in the peripapillary area with visual field defects in one or both hemifields. Materials and Methods This cross-sectional study was conducted at a tertiary eye care center in northern Karnataka for one year, enrolling 100 eyes from 50 primary open-angle glaucoma (POAG) patients with visual field abnormalities. Fundus color stereoscopic photographs were taken using a Canon digital camera, and diameters of the superior and inferior temporal arteries (STA and ITA) and veins (STV and ITV) in the peripapillary area were measured. Visual field defects were categorized, and statistical analyses were performed to correlate retinal vessel calibers with field defect locations. Results Participants had a mean age of 89.68 years, with 72% male. Visual field defects included superior arcuate scotoma (20%), inferior arcuate scotoma (32%), double arcuate scotoma (30%), and tubular vision (18%). Significant vessel caliber changes were observed: for superior hemifield defects, the mean STA: ITA ratio was 1.15 (p = 0.001), and for inferior defects, it was 0.94 (p = 0.04). STV: ITV ratios also showed significant changes corresponding to visual field defects. Eyes with defects in both hemifields showed pronounced narrowing, particularly in inferotemporal vessels. Conclusions Decreased retinal vessel caliber is significantly associated with visual field defects in primary open-angle glaucoma and can be a valuable diagnostic parameter tool for assessing glaucomatous damage and the progression and severity of POAG.

The Optical Nature of Myopic Changes in Retinal Vessel Caliber

PurposeDimensional measures of retinal features are subject to the optical influence of ocular magnification. We examined the impact of ocular magnification on the association between axial length (AL) and measurements of retinal vessel calibre in fundus photographs. DesignCross-sectional study. ParticipantsEighty-two normal right eyes from healthy participants aged 16-31 years. MethodsCentral retinal arteriolar and venular equivalents (CRAE and CRVE) were derived from colour fundus photographs using semi-automated software. Ordinary least squares linear regression was used to assess the influence of AL (independent variable) on CRAE and CRVE, controlling for age, sex and ethnicity, both before and after magnification correction using different formulae. These formulae estimate magnification based on different ocular parameters: AL only (Bennnett’s formula), refractive error only (Bengtsson’s formula) and refractive error combined with keratometry (Littmann’s formula). Previous research has primarily relied on Bengtsson’s formula, which is less accurate than Bennett’s formula. We also examined the impact of treating the non-telecentric fundus camera used in this study as telecentric when applying these magnification correction formulae. Main Outcome MeasuresCentral retinal arteriolar and venular equivalents (in pixels). ResultsBefore magnification correction, increasing AL was associated with decreasing CRAE (β: -0.49, 95% CI: -0.89 to -0.09, p=0.02) and CRVE (β: -0.91, 95% CI: -1.62 to -0.20, p=0.01). After magnification correction, this observation was no longer evident, regardless of the correction formula applied. When inappropriately assuming the fundus camera to be telecentric, we observed a bias towards increasing magnification-corrected CRAE and CRVE with increasing AL (β coefficients were positive or became more positive), reaching statistical significance (p<0.05) for CRAE corrected using Bennett’s or Littmann’s formula, and for CRVE corrected using Bennett’s formula. ConclusionsFailing to correct for ocular magnification results in apparent narrowing of vessels in longer eyes, while inappropriate assumptions about telecentricity during magnification correction introduce an optical artifact that causes apparent widening of vessels. These findings suggest that myopic changes in retinal vessel calibre are optical (not biological) in nature. Proper correction of this effect to accurately derive dimensional measures is a crucial—yet often overlooked—methodological consideration in “oculomics” research investigating retinal biomarkers of systemic conditions.

A dynamic multiscale model of cerebral blood flow and autoregulation in the microvasculature

Models of the micro-circulatory blood flow in the brain can play a key role in understanding the variety of cerebrovascular diseases that occur in the microvasculature. These conditions are often linked to structural modifications in the vessel network, alterations in the blood flow patterns, as well as impairment in the autoregulatory response, all of which are pathological changes that the model should be able to address if it were to have any clinical value. Furthermore, if the model results were to be validated against clinical MRI data, the model simulations need to be computationally feasible when used on networks on the scale of an MRI voxel. This requires some form of an upscaling approach that bypasses the need for an explicit architectural representation of the whole network while maintaining the relevant anatomical connections. To this end, we developed a hybrid multiscale model of blood flow and autoregulation that traces the dynamic changes in blood flow, volume, and pressure in the cortical microvasculature, where the discrete topology of the penetrating vessels is preserved, and these are then appropriately coupled to the homogenised capillary bed by a spatially distributing support function in the terminal endings. In contrast to the other multiscale models, the model developed here accounts for the dynamic physiological phenomena of the blood flow and the autoregulation processes in the microvessels. We show how the adaptive meshing scheme for the capillary bed developed in this study can be employed to ensure a scale-invariant coupling formulation and numerically accurate simulations, all without compromising the computational feasibility of the model. A statistically accurate cortical network on the scale of an MRI voxel is generated, and the model parameter values are calibrated using a Monte Carlo Filtering analysis to ensure that the model results are physiologically informed. The model is found to be able to capture the steep pressure gradients that have been reported to occur at coupling interfaces. Furthermore, in response to an upstream pressure drop, the network is found to be able to recover cerebral blood flow while exhibiting the characteristic autoregulatory behaviour in terms of changes in vessel calibre and the biphasic flow response. Overall, the model developed here offers a high-quality characterisation of dynamic flow and autoregulation in the microvasculature at improved computational efficiency and lays the ground for whole-brain dynamic simulations.

A network-based model of dynamic cerebral autoregulation.

Cerebrovascular diseases continue to be one of the leading causes of morbidity and mortality in humans. Abnormalities in dynamic cerebral autoregulation (dCA) have been implicated in many of these disease conditions. Accurate models are therefore needed to better understand the complex pathophysiology behind impaired dCA. We thus present here a simple framework for modelling a vessel-driven network model of dCA in the microvasculature, as opposed to the conventional compartmental modelling approach. Network models incorporate the actual connectivity and anatomy of the vasculature, thereby allowing us to include and trace changes in the calibre and morphology of individual vessels, investigate the spatial specificity and heterogeneity of the various control mechanisms to help disentangle their contributions, and link the model parameters to the actual network physiology. The proposed control feedback mechanisms are incorporated at the level of the individual vessel, and the dynamic pressure and flow fields are solved for here within a simple vessel network. In response to an upstream pressure drop, the network is found to be able to recover cerebral blood flow (CBF) while exhibiting the characteristic autoregulatory behaviour in terms of changes in vessel calibre and the biphasic flow response. We assess the feasibility of our formulation in larger networks by comparing the simulation results to those obtained using a one-dimensional (1D) model of CBF applied to the same microvasculature network and find that our model results are in very good agreement with the 1D solution, while significantly reducing the computational cost, thus enabling more detailed models of network behaviour to be adopted in the future. Accurate and computationally feasible models of dCA that are more representative of the vasculature can help increase the translatability of haemodynamic models into the clinical environment, which would help develop more informed treatment guidelines for patients with cerebrovascular diseases.

Evaluation of microvascular density and retinal vessel diameter in gestational and type 2 diabetes using swept-source OCT-A technology

To assess foveal and parafoveal retinal and choroidal microvascular changes using optical coherence tomography angiography (OCTA) and changes in retinal vessel caliber in pregnant women with gestational diabetes mellitus (GDM), non-pregnant female patients with type 2 diabetes mellitus (DM2), and healthy pregnant female subjects. The study was conducted cross-sectionally and composed of three age-matched groups: 32 near-term pregnant women with GDM (GDM group), 32 non-pregnant female patients with a recent diagnosis of DM2 (DM2 group), and 32 healthy near-term pregnant female subjects. Vessel density (VD) and vessel diameter were the main outcomes. Detailed ophthalmic examinations were performed for each participant, including swept-sourceOCTA measurements consisting of superficial, deep, outer retinal and choroidal vessel density. The average VD values in the central fovea of the superficial and deep retina were significantly lower in the GDM group (P=0.001 for both, between the three groups), whereas the mean VD in the parafoveal nasal sector of the deep retina was significantly lower in the DM2 group (P=0.008, between the three groups). There were no significant differences in the foveal or parafoveal VD measurements of the outer retina and choriocapillaris (P>0.05 for all). There were statistically significant differences in the retinal venous diameter and arterial vein ratio in the GDM and DM2 groups compared to the control group (P=0.001 for all). The microvascular density changes seen on OCTA images of pregnant women with GDM are remarkable. These changes in retinal vessels appeared to occur rapidly after the onset of the metabolic impairment or might be the reflection of previous insulin resistance as well, as in recent diabetes. Our results also suggest that these changes may be more significant in a GDM pregnant woman than in a pregnant, established diabetic patient.

Measuring hyperemic response to light flicker stimulus using continuous laser speckle flowgraphy in mice

Alterations in neurovascular coupling have been associated with various ocular, cerebral, and systemic vascular disorders. In the eye, changes in vessel caliber by dynamic vessel analysis have been used to measure neurovascular coupling following a light flicker stimulus. Here, we present a new protocol for quantifying light-flicker induced hyperemia in the C57/Bl6J mouse retina using laser speckle flowgraphy (LSFG). Our protocol was adapted from protocols used in human subjects. By acquiring continuous time series data, we detected significant increase in blood flow. These responses are maintained with low variability over multiple imaging sessions, indicating these methods may be applied in serial studies of neurovascular coupling.

Прогрессирование начальной диабетической ретинопатии: связь с состоянием углеводного обмена

Актуальность. Распознавание ранних стадий диабетической ретинопатии (ДР) у пациентов с сахарным диабетом 2-го типа (СД2) и прогнозирование их прогрессии имеет важное значение и является актуальной задачей современной офтальмологии. Цель исследования — изучить особенности возникновения и прогрессирования начальных стадий ДР и установить связь со степенью нарушения углеводного обмена у пациентов с СД2. Материалы и методы. Был обследован 91 пациент (182 глаза) с СД2. Согласно ETDRS по системе клинических признаков Airlie House определяли микроаневризмы (МА), микрогеморрагии (МГ), интраретинальные микрососудистые аномалии (ИРМА), ретинальные венозные аномалии, неперфузию сетчатки и связь их развития со степенью нарушения углеводного обмена у больных СД2. Результаты. У большинства пациентов (72,5 %) на начало исследования ДР не было (уровень ETDRS составил 0–10 на обоих глазах). У остальных (27,5 %) на одном глазу уровень ETDRS был 10, а на другом отмечены единичные изменения калибра сосудов, расширение и извитость вен, ИРМА или МГ, что соответствовало уровню ETDRS 14/15. У этих пациентов давность СД2 была больше (в среднем на 3 года), а нарушения углеводного обмена были более выраженными. В течение 1 года наблюдения глазные изменения прогрессировали по-разному: при отсутствии ДР в начале исследования прогрессия была отмечена в 50 % случаев, тогда как при их наличии — в 92 %. Пациенты с прогрессией имели больший стаж диабета и худшие показатели углеводного обмена. Выводы. Установлено, что диабетические изменения сетчатки начинаются с одиночных сосудистых изменений, при наличии которых в течение 1 года ДР развивается в большинстве случаев.

Advanced imaging to assess longitudinal vascular changes in brain metastases treated with checkpoint inhibition.

3059 Background: Immune checkpoint inhibitors (ICI) have recently been shown to be effective for brain metastases (BM) in melanoma and lung cancer. Several studies demonstrate that 20-50% of BM patients respond to ICI. The reasons behind this wide variability in treatment response is not clear. Therefore, using physiologic imaging, we seek to identify the longitudinal biological changes exerted on BM as a result of ICI administration. Methods: Given the importance of aberrant tumor vasculature in cancer proliferation, we have focused on assessing changes in vascular physiology. We analyzed standard post-contrast and dynamic susceptibility contrast (DSC) MRI to identify characteristic vascular signatures as part of an ongoing Phase 2 study of pembrolizumab for patients with untreated or progressive, previously treated BM from any histology. Tumor volume measurements were calculated by summating all enhancing voxels. As per modified RECIST and RANO criteria for immunotherapy, volumetric increase of &gt; 40% was defined as progressive disease (PD), a decrease of &gt; 60% as partial response (PR), and stable disease (SD) as between -60% and +40%. Results: 35 patients, out of the total cohort of 60, have undergone DSC-MRI analysis. Histologies include 15 with breast cancer, 6 with non-small cell lung cancer, 4 with melanoma, and 10 with other cancers. At baseline, the total number of BM was 1-50+ per patient. Based on summing the entire enhancing intracranial disease burden, best volumetric responses for the 35 evaluable patients include 4 PR, 12 SD, and 19 PD. Thus far, we found that ICI-resistant BM had a 50% increase in cerebral blood flow (CBF), 105% increase in cerebral blood volume (CBV), a 15% increase in mean transit time (MTT), and an 80% increase in vessel caliber at 6 weeks post-treatment. On the other hand, ICI-responsive BM had no change in CBF, a 33% increase in CBV, a 10% decrease in MTT, and no change in vessel caliber. Ongoing analysis to uncover additional vascular changes (e.g. tumor oxygenation, vessel size index) within BM to ICI are pending. Conclusions: Our data provides evidence that effective ICI for BM is associated with unique intra-tumoral vascular physiology. With final analysis, we will uncover other facets of vascular physiology that correlate with ICI response, and may reveal mechanisms of response/resistance within tumors to ICI.

Role of arterial duplex of both lower limbs in the evaluation of diabetic foot

Introduction Diabetes mellitus (DM) is a metabolic disorder characterized by hyperglycemia and dyslipidemia. Abnormalities in nutrient metabolism and vascularity resulting from DM lead to lower limb arterial diseases and ischemia, and this leads to infection, foot ulcers, and impairment of wound healing. Color Doppler ultrasound is a widely available noninvasive technique in the assessment of arterial affection of lower limbs that occur with DM. Color Doppler ultrasound has lots of advantages over other diagnostic imaging modalities; it is a feasible modality available in nearly all hospitals, being cheap, accurate, and safe. Aim The aim was to highlight the role of arterial duplex to better delineate vascular anatomy, localize the obstruction, assess the severity of stenosis, and detect the presence of collaterals, and distal runoff in patients with diabetic foot disease. Materials and methods Ultrasound color and Doppler examinations were performed to 20 patients previously diagnosed to have DM; the arterial supply of lower extremities was divided into these segments: common iliac artery, external iliac artery, common femoral artery, superficial femoral artery, profunda femoris artery, popliteal artery, anterior tibial artery, posterior tibial artery, peroneal artery, and dorsalis pedis. Arterial lesions were located by changes in vessel caliber, changes in color flow patterns, and broadening of Doppler waveform, quantified by measuring the peak systolic velocity (PSV) ratio across a lesion and by comparing the PSV within stenosis with that proximal to the lesion; this ratio was independent of individual variations in blood pressure, vascular compliance, and cardiac function. Results In all, there were 20 patients (400 segments), 35 segments showed significant stenosis (luminal narrowing ≥50% of artery diameter and PSV ratio ≥2), 21 segments were occluded, eight of them were with no distal collateral refilling, and 100 segments showed nonsignificant stenosis (luminal narrowing Conclusion Duplex ultrasound is an accurate easily acquired noninvasive diagnostic modality in diabetic foot patients. There was very high incidence of atherosclerosis in diabetic foot patients with more affection in below-knee arteries.

Effect of immunosuppressive therapy on oxygen saturation and diameter of retinal vessels in initial onset acute uveitis associated with Vogt-Koyanagi-Harada disease.

To demonstrate changes in oxygen saturation and calibre of retinal vessels in initial-onset acute uveitis associated with Vogt-Koyanagi-Harada (VKH) disease at baseline and during immunosuppressive therapy. In this prospective study, 22 patients (44 eyes) were studied. Retinal oximetry measurements were performed using the noninvasive spectrophotometric retinal oximeter (Oxymap T1) at baseline and at 1-3months, 4-6months, 5-7months and more than 9months after treatment. At baseline, mean logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) was 1.12±0.78 (Snellen equivalent, 20/265). Arteriolar and venular oxygen saturations were 108±7% and 70±9%, respectively and calibres of arterioles and venules were 12.1±1.1 pixels and 16.9±1.4 pixels, respectively. At 4-6months of follow-up, logMAR BCVA was almost maximum (0.08±0.1, Snellen equivalent 20/24; p<0.001) and thereafter remained almost unchanged. After immunosuppressive therapy, arteriolar and venular oxygen saturation values continued to decrease up to >9months of follow-up (92±7% and 56±10%, respectively; p<0.001 for both arterioles and venules). Similarly, arteriolar and venular calibres continued to decrease up to >9months of follow-up to 11.4±0.9 pixels (p=0.006) and 15.6±1.3 pixels (p=0.001), respectively. Eyes with initial-onset acute uveitis associated with VKH disease have increased oxygen saturation and calibres of retinal vessels at baseline. Immunosuppressive therapy normalizes these changes and in a similar pattern improves BCVA.

Analysis of Foveal and Parafoveal Microvascular Density and Retinal Vessel Caliber Alteration in Inactive Graves' Ophthalmopathy.

Purpose We aimed to evaluate foveal and parafoveal density using optical coherence tomography angiography and the alteration on the retinal vessel diameter in patients with inactive Graves' ophthalmopathy compared to age-matched normal population. Materials and Methods. Patients with inactive Graves' ophthalmopathy (study group) and healthy individuals (control group) were enrolled in the cross sectionally designed study. The optical coherence tomography angiography parameters and retinal vessel diameter measurements were assessed between the study and control groups. Foveal and parafoveal microvascular density in the retina was measured using optical coherence tomography angiography. Retinal artery and vein diameter and artery/vein ratio were assessed for retinal vessel caliber changes. Results Patients with inactive Graves' ophthalmopathy had higher values of intraocular pressure, proptosis, and axial length (P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, P=0.001, Conclusion Optical coherence tomography angiography could be a novel and promising noninvasive diagnostic technique in patients with inactive Graves' ophthalmopathy to detect foveal and parafoveal vessel density changes compared to healthy subjects. The decrease of retinal vessel diameter might be observed in patients with inactive graves ophthalmopathy.

Investigating spontaneous retinal venous pulsation using Doppler optical coherence tomography

We demonstrate the advantages of optical coherence tomography (OCT) imaging for investigation of spontaneous retinal venous pulsation (SRVP). The pulsatile changes in venous vessel caliber are analyzed qualitatively and quantitatively using conventional intensity-based OCT as well as the functional extension Doppler OCT (DOCT). Single-channel and double-channel line scanning protocols of our multi-channel OCT prototype are employed to investigate venous pulsatile caliber oscillations as well as venous flow pulsatility in the eyes of healthy volunteers. A comparison to recordings of scanning laser ophthalmoscopy (SLO) – a standard en-face imaging modality for evaluation of SRVP – is provided, emphasizing the advantages of tomographic image acquisition. To the best of our knowledge, this is the first quantitative time-resolved investigation of SRVP and associated retinal perfusion characteristics using OCT.

The Role of Hemodynamics in Intracranial Bifurcation Arteries after Aneurysm Treatment with Flow-Diverter Stents.

Treatment of intracranial bifurcation aneurysms with flow-diverter stents can lead to caliber changes of the distal vessels in a subacute phase. This study aims to evaluate whether local anatomy and flow disruption induced by flow-diverter stents are associated with vessel caliber changes in intracranial bifurcations. Radiologic images and demographic data were acquired for 25 patients with bifurcation aneurysms treated with flow-diverter stents. Whisker plots and Mann-Whitney rank sum tests were used to evaluate if anatomic data and caliber changes could be linked. Symmetry/asymmetry were defined as diameter ratio 1 = symmetric and diameter ratio <1 = asymmetric. Computational fluid dynamics was performed on idealized and patient-specific anatomies to evaluate flow changes induced by flow-diverter stents in the jailed vessel. Statistical analysis identified a marked correspondence between asymmetric bifurcation and caliber change. Symmetry ratios were lower for cases showing narrowing or subacute occlusion (medium daughter vessel diameter ratio = 0.59) compared with cases with posttreatment caliber conservation (medium daughter vessel diameter ratio = 0.95). Computational fluid dynamics analysis in idealized and patient-specific anatomies showed that wall shear stress in the jailed vessel was more affected when flow-diverter stents were deployed in asymmetric bifurcations (diameter ratio <0.65) and less affected when deployed in symmetric anatomies (diameter ratio ∼1.00). Anatomic data analysis showed statistically significant correspondence between caliber changes and bifurcation asymmetry characterized by diameter ratio <0.7 (P < .001). Similarly, computational fluid dynamics results showed the highest impact on hemodynamics when flow-diverter stents are deployed in asymmetric bifurcations (diameter ratio <0.65) with noticeable changes on wall sheer stress fields. Further research and clinical validation are necessary to identify all elements involved in vessel caliber changes after flow-diverter stent procedures.

Dynamic changes in retinal vessel diameter during acute hyperglycemia in type 1 diabetes

AimsTo investigate changes in retinal vessel diameter during acute hyperglycemia in patients with type 1 diabetes. MethodsWe conducted a study on 11 subjects with type 1 diabetes. Euglycemia was maintained for 3h followed by induction of hyperglycemia and simultaneous bolus of rapid acting insulin. Two fundus photos were captured during euglycemia and five fundus photos, blood glucose and blood pressure were taken every 30min for 2.5h post-prandial. Central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE) were measured over the study visit and examined using generalized linear mixed models. ResultsIn a multivariate mixed model, mean CRAE and CRVE were reduced at 90min post-prandial in both zones B and C. In repeated measures analysis, arterioles exhibited a significant association with change in vessel caliber per change in blood glucose. Inconsistent effects of blood pressure on vessel diameter were also measured. ConclusionsWe document a change in retinal vessel diameter during acute hyperglycemia in persons with type 1 diabetes. Larger controlled studies are required to further investigate this phenomenon and to more accurately assess if hyperglycemia has direct effects on retinal vessel diameter.

Association between Retinal Arteriolar and Venule Calibre with Prevalent Heart Failure: A Cross-Sectional Study.

BackgroundThere is evidence to suggest that microvascular disease, particularly diabetic retinopathy, plays a role in the pathogenesis of HF. However, whether changes in retinal vessel calibre predicts HF is unclear. The purpose of this study was to examine the association of retinal microvascular structure with prevalent heart failure (HF).MethodsThe Australian Heart Eye Study (AHES) is a cross-sectional study that surveyed 1680 participants who presented to a tertiary referral hospital for the evaluation of potential coronary artery disease by coronary angiography. Retinal vessel calibre was graded using retinal photography and participants’ self-reported echocardiography-confirmed HF was obtained via an extensive medical questionnaire.ResultsThere were 107 participants (8.1%) with prevalent self-reported HF. Persons with wider retinal arteriolar calibre (comparing highest versus lowest tertile or reference) were more likely to have prevalent HF (OR 3.5; 95% CI, 1.7–7.2) when adjusted for age and sex. After further adjustment for body mass index, hypertension, diabetes, smoking status, triglycerides and estimated glomerular filtration rate, this association remained significant (OR 4.5; 95% CI, 2.0–9.8). After further stratification, this association remained significant among participants with diabetes (OR 10.3; 95% CI, 2.7–39.3) but not in those without diabetes (OR 2.7; 95% CI, 0.9–7.5). The strength of this association was not dependent on the length of history of diabetes, or retinopathy status. There was no significant association between retinal venular calibre and prevalence of HF.ConclusionsWider retinal arteriolar diameter was significantly and independently associated with prevalent HF in participants of a cross-sectional study. This association was significant stronger among participants with diabetes compared to without diabetes. No association was found between retinal venule calibre with prevalent HF.

Retinal vessel calibers predict long-term microvascular complications in type 1 diabetes: the Danish Cohort of Pediatric Diabetes 1987 (DCPD1987).

Diabetic neuropathy, nephropathy, and retinopathy cause significant morbidity in patients with type 1 diabetes, even though improvements in treatment modalities delay the appearance and reduce the severity of these complications. To prevent or further delay the onset, it is necessary to better understand common underlying pathogenesis and to discover preclinical biomarkers of these complications. Retinal vessel calibers have been associated with the presence of microvascular complications, but their long-term predictive value has only been sparsely investigated. We examined retinal vessel calibers as 16-year predictors of diabetic nephropathy, neuropathy, and proliferative retinopathy in a young population-based Danish cohort with type 1 diabetes. We used semiautomated computer software to analyze vessel diameters on baseline retinal photos. Calibers of all vessels coursing through a zone 0.5-1 disc diameter from the disc margin were measured and summarized as the central artery and vein equivalents. In multiple regression analyses, we found wider venular diameters and smaller arteriolar diameters were both predictive of the 16-year development of nephropathy, neuropathy, and proliferative retinopathy. Early retinal vessel caliber changes are seemingly early markers of microvascular processes, precede the development of microvascular complications, and are a potential noninvasive predictive test on future risk of diabetic retinopathy, neuropathy, and nephropathy.

Ocular pulse amplitude and retinal vessel caliber changes after intravitreal ranibizumab.

The purpose of the present study was to examine the effects of intravitreal ranibizumab on ocular pulse amplitude (OPA) and retinal vessel caliber (RVC) in wet age-related macular degeneration (AMD). Thirty-two eyes of 32 wet AMD patients were included in this case series. Three consecutive monthly injections of ranibizumab were performed. The OPA was measured with the Pascal dynamic contour tonometer. RVC measurements were taken with spectral-domain optical coherence tomography. Pre-injection mean OPA value was 2.55±0.76mmHg and post-injections mean OPA value was 2.79±0.88mmHg at the last visit (p=0.10). Pre-injection mean arteriole and venule RVC were 96.7±9.4 and 125.9±8.4µm; while post-injections arteriole and venule RVC were 96.0±8.7 and 125.6±8.9µm, respectively (p>0.05). OPA and RVC are unchanged after triple intravitreal ranibizumab injections, indicating that this treatment does not significantly alter gross retina-choroidal vasculature and hemodynamics.

Enterprise stenting for intracranial aneurysm treatment induces dynamic and reversible age-dependent stenosis in cerebral arteries

BackgroundAlthough intracranial stenting has been associated with in-stent stenosis, the vascular response of cerebral vessels to the deployment of the Enterprise vascular reconstruction device is poorly defined.ObjectiveTo evaluate the change...

LOCALIZED CHANGES IN RETINAL VESSEL CALIBER AFTER FOCAL/GRID LASER TREATMENT IN PATIENTS WITH DIABETIC MACULAR EDEMA

To compare retinal vessel caliber changes at the macula region and surrounding the optic disk after focal/grid laser treatment for diabetic macular edema. The study included 69 eyes from 46 patients treated with focal/grid laser for diabetic macular edema. Retinal photographs were taken <6 months before and 2 months and 12 months after focal/grid photocoagulation treatment. The diameters of retinal vessels around macula and the optic disk were measured separately before and after treatment. Optic disk and macular diameters were summarized into central retinal arteriolar and venular equivalent and macular retinal arteriolar and venular equivalent. Median age and duration of diabetes was 60 years and 13 years. There was a statistically significant decrease in diameter of the macular arterioles (macular retinal arteriolar equivalent 73.5 vs. 72.0 μm, P = 0.04) and venules (macular retinal venular equivalent 63.5 vs. 62.4 μm, P = 0.02) after treatment but no difference in central retinal arteriolar equivalent or central retinal venular equivalent before and after treatment. Retinal vascular calibers in control eyes did not change throughout the study. The diameters of macular vessels decreased after focal/grid laser treatment in most eyes. In contrast, vessel calibers at the optic disk did not change. Quantitative measurement of macular vessels may allow physicians to monitor the progress and success of diabetic macular edema treatment.

α1D-Adrenoceptors are responsible for the high sensitivity and the slow time-course of noradrenaline-mediated contraction in conductance arteries.

The objective of this study was to determine whether the different time-course characteristics of α1-adrenoceptor-mediated contraction in arteries can be related to the subtypes involved. Contractile responses to noradrenaline (NA) were compared with inositol phosphate accumulation and extracellular signal-regulated kinase (ERK)1/2 phosphorylation after α1-agonist stimuli in the same vessels in the presence or absence of α1-antagonists in rat or in α1-subtype knockout (KO) mice. Aorta, where α1D-AR is the main functional subtype, had higher sensitivity to NA (in respect of inositol phosphate [IP], pERK1/2, and contractile response) than tail artery, where the α1A-adrenoceptor subtype is predominant. Furthermore, the contraction in aorta exhibited a slower decay after agonist removal and this was consistent in all strains harboring α1D-adrenoceptors (from rat, α1B-KO, and wild-type [WT] mice) but was not observed in the absence of the α1D-adrenoceptor signal (α1D-adrenoceptor blocked rat aorta or aorta from α1D-KO). IP formation paralleled α1-adrenoceptor-mediated contraction (agonist present or postagonist) in aorta and tail artery. High sensitivity to agonist and persistence of response after agonist removal is a property of α1D-adrenoceptors. Therefore, the preponderance of this subtype in noninnervated conductance arteries such as aorta allows responsiveness to circulating catecholamines and prevents abrupt changes in vessel caliber when the stimulus fluctuates. Conversely, in innervated distributing arteries, high local concentrations of NA are required to activate α1A-adrenoceptors for a response that is rapid but short lived allowing fine adjustment of the contractile tone by perivascular sympathetic nerves.