Blood viscosity, coagulation, and activated protein C resistance in central retinal vein occlusion: a population controlled study

Whole Blood Viscosity and Cerebral Blood Flow in Acute Ischemic Stroke

Existing effective treatments for ischemic stroke restore blood supply to the ischemic region using thrombolysis or mechanical removal of clot. However, it is increasingly recognized that successful removal of occlusive thrombus from the large artery-recanalization, may not always be accompanied by successful restoration of blood flow to the downstream tissues-reperfusion. Ultimately, brain tissue survival depends on cerebral perfusion, and a functioning microcirculation. Because capillary diameter is often equal to or smaller than an erythrocyte, microcirculation is largely dependent on erythrocyte rheological (hemorheological) factors such as whole blood viscosity (WBV). Several studies in the past have demonstrated elevated WBV in stroke compared with healthy controls. Also, elevated WBV has shown to be an independent risk factor for stroke. Elevated WBV leads to endothelial dysfunction, decreases nitric oxide-dependent flow-mediated vasodilation, and promotes hemostatic alterations/thrombosis, all leading to microcirculation sludging. Compromised microcirculation further leads to decreased cerebral perfusion. Hence, modulating WBV through pharmacological agents might be beneficial to improve cerebral perfusion in stroke. This review discusses the effect of elevated WBV on endothelial function, hemostatic alterations, and thrombosis leading to reduced cerebral perfusion in stroke.

Red Blood Cells: A Newly Described Partner in Central Retinal Vein Occlusion Pathophysiology?

Central retinal vein occlusion (CRVO) is a frequent retinal disorder inducing blindness due to the occlusion of the central vein of the retina. The primary cause of the occlusion remains to be identified leading to the lack of treatment. To date, current treatments mainly target the complications of the disease and do not target the primary dysfunctions. CRVO pathophysiology seems to be a multifactorial disorder; several studies did attempt to decipher the cellular and molecular mechanisms underlying the vessel obstruction, but no consensual mechanism has been found. The aim of the current review is to give an overview of CRVO pathophysiology and more precisely the role of the erythroid lineage. The review presents emerging data on red blood cell (RBC) functions besides their role as an oxygen transporter and how disturbance of RBC function could impact the whole vascular system. We also aim to gather new evidence of RBC involvement in CRVO occurrence.

Effects of sarpogrelate on blood viscosity

The objective of the present study was to evaluate the effects and safety of sarpogrelate hydrochloride (sarpogrelate) in patients with elevated blood viscosity (BV), after 12 and 24 weeks of twice (BID) or thrice (TID) daily administrations of sarpogrelate (100 mg). The participants received oral sarpogrelate administration for 24 weeks and visited the hospital every 12 ± 2 week for blood viscosity measurements at shear rates of 5 and 300 s^-1. The BV measured at shear rate of 5 s^-1 in male patients decreased significantly from 18.91 cP at the baseline to 16.3 cP after 24 weeks of sarpogrelate administration (13.6 % drop, p < 0.001). The BV measured at 5 s^-1 in female decreased more significantly from 17.5 cP at the baseline to 13.4 cP after 24 weeks of sarpogrelate administration (23.0 % drop, p < 0.001). In summary, sarpogrelate may be considered as a possible therapeutic option for improving BV in patients with elevated blood viscosity. In particular, the reduction of the low-shear BV with the help of a viscosity-reducing drug such as sarpogrelate may be considered as a potentially new pharmacological tool for microvascular disease.

Effect of a Dexamethasone Implant on Rheological Blood Parameters in Patients Treated for Retinal Vein Thrombosis

Purpose

To assess the effect of the prolonged-release dexamethasone implant (Ozurdex) in patients with retinal venous thrombosis on blood rheological parameters and evaluate the impact on morphological and functional parameters.

Methods

Prospective cross-sectional study involved 35 subjects treated with central retinal vein and vein branch occlusion with intravitreal dexamethasone implant and 35 healthy subjects in control group. Hematocrit, blood and plasma viscosity, erythrocyte aggregation amplitude (EAA), index (EAI), aggregation half-life time (EAT1/2), and erythrocyte deformability (ED) were evaluated. The best-corrected visual acuity (BCVA), central retinal thickness (CRT) and visual field (VF) were examined. All the parameters were examined at the baseline, 7 and 30 days after the treatment. The results were analyzed with correlation and regression and compared to the baseline values.

Results

In the studied group, three hemorheological parameters improved as early as on the 7th day after the drug administration, and this improvement remained at a similar level on the 30th day. The EAA increased by 21.26% on day 7 and by 19.78% on day 30, the EAI decreased by 10.55% on day 7 and by 9.14% on day 30 and the EAT1/2 time increased by 38.50% on day 7 and by 31.02% on day 30. On day 7, the BCVA was improved by 1 row, CRT was reduced by 170.77 µm (24.49%), and the VF was improved by 9.8 dB (49.92%) compared to baseline parameters. On day 30, the BCVA was improved by three rows, CRT reduced by 244.68 µm (35.09%), and VF improved by 12.09 dB (61.59%).

Conclusion

The intravitreal dexamethasone implant used in treating macular oedema in patients with RVO has a statistically significant effect on some rheological parameters of blood, reduction of CRT and clinical improvement in BCVA and VF.

Changes of plasma nitric oxide, endothelin-1, and blood coagulation following intravitreal conbercept

Intravitreal anti-VEGF (anti-vascular endothelial growth factor) biologics have revolutionized the pharmacological management of chorioretinal diseases. However, the systemic adverse events such as stroke or bleeding are the concerns for many patients and physicians. The mechanism to develop these side effects are poorly understood. Consecutive 95 patients with retinal diseases were studied for their blood activated partial thromboplastin time (APTT), prothrombin time (PT), international normalized ratio (INR), and concentration of fibrinogen before and after intravitreal conbercept. Additionally, plasma nitric oxide (NO) and endothelin-1 (ET-1) were investigated on 38 of the 95 patients. Compared with the pre-injection, 4-week post-injection values of APTT and PT were increased by 0.582 s (p = 0.038, paired t test) and by 0.086 s (p = 0.080, paired t test; p = 0.0475, Sign test), respectively. At the same time, fibrinogen decreased by 0.048 g/L. Plasma levels of NO or ET-1 or VEGF did not significantly change from pre-injection levels. Our findings advanced the understanding of mechanism for systemic side effects associated with intravitreal anti-VEGF and emphasized paying more attention to higher risk of possible bleedings for patients following intravitreal conbercept.

Platelet and Thrombophilia-Related Risk Factors of Retinal Vein Occlusion

Retinal vein occlusion (RVO) is a heterogenous disorder in which the formation of a thrombus results in the retinal venous system narrowing and obstructing venous return from the retinal circulation. The pathogenesis of RVO remains uncertain, but it is believed to be multifactorial and to depend on both local and systemic factors, which can be divided into vascular, platelet, and hypercoagulable factors. The vascular factors include dyslipidaemia, high blood pressure, and diabetes mellitus. Regarding the platelet factors, platelet function, mean platelet volume (MPV), platelet distribution width (PDW), and platelet large cell ratio (PLCR) play key roles in the diagnosis of retinal vein occlusion and should be monitored. Nevertheless, the role of a hypercoagulable state in retinal vein occlusion remains unclear and requires further studies. Therefore, the following article will present the risk factors of RVO associated with coagulation disorders, as well as the acquired and genetic risk factors of thrombophilia. According to Virchow’s triad, all factors mentioned above lead to thrombus formation, which causes pathophysiological changes inside venous vessels in the fundus of the eye, which in turn results in the vessel occlusion. Therefore, a diagnosis of retinal vein occlusion should be based on both eye examination and general examination, including laboratory tests.

A fast numerical method for oxygen supply in tissue with complex blood vessel network

Angiogenesis plays an essential role in many pathological processes such as tumor growth, wound healing, and keloid development. Low oxygen level is the main driving stimulus for angiogenesis. In an animal tissue, the oxygen level is mainly determined by three effects—the oxygen delivery through blood flow in a refined vessel network, the oxygen diffusion from blood to tissue, and the oxygen consumption in cells. Evaluation of the oxygen field is usually the bottleneck in large scale modeling and simulation of angiogenesis and related physiological processes. In this work, a fast numerical method is developed for the simulation of oxygen supply in tissue with a large-scale complex vessel network. This method employs an implicit finite-difference scheme to compute the oxygen field. By virtue of an oxygen source distribution technique from vessel center lines to mesh points and a corresponding post-processing technique that eliminate the local numerical error induced by source distribution, square mesh with relatively large mesh sizes can be applied while sufficient numerical accuracy is maintained. The new method has computational complexity which is slightly higher than linear with respect to the number of mesh points and has a convergence order which is slightly lower than second order with respect to the mesh size. With this new method, accurate evaluation of the oxygen field in a fully vascularized tissue on the scale of centimeter becomes possible.

Electrical Analysis Of Normal And Diabetic Blood For Evaluation Of Aggregation And Coagulation Under Different Rheological Conditions

Introduction

Erythrocyte aggregation and blood coagulation are of great interest and are still under investigation by many researchers. Erythrocytes have a direct effect on hemorheological properties. Real-time in vitro studies on blood coagulation and aggregation provide a chance to understand their mechanisms in normal and pathological conditions. Additionally, this method offers control over the physical and chemical conditions during the study.

Objective

The present study introduced a simple in vitro technique to study blood aggregation and coagulation under controlled conditions.

Methods

The technique used in this study is based on the measurement of the electrical properties of blood. A simple flow chamber was made from two cylinders with a gap between them. The outer cylinder remains stationary, and the inner cylinder rotates about its axis. The inner cylinder velocity is controlled by a stepper motor. Blood samples are introduced in the gap between the two cylinders. Capacitance and impedance of blood samples were recorded by two electrodes attached to the outer cylinders and in direct contact with blood.

Results

Quantitative parameters were extracted from the capacitance and impedance time courses. These parameters were used to describe the aggregation and coagulation processes under different shear rates. Strong correlations between the aggregation index and shear rate were found for normal and diabetic blood samples. Additionally, strong negative correlations of coagulation time were found for normal and diabetic blood samples. In conclusion, the electrical analysis of blood reflects well the interactions between internal blood contents.

Conclusion

The parameters extracted from this technique can be used in the quantitative description of hemorheological processes under different physical conditions.

Bilateral Central Retinal Vein Occlusion, multiple dental implants and severe glomerulonephtitis - Any connection?

We present a case of Bilateral Central Retinal Vein Occlusion in a patient who received 11 dental implants and later developed idiopathic glomerulonephritis with renal failure.

Altered blood rheology and impaired pressure-induced cutaneous vasodilation in a mouse model of combined type 2 diabetes and sickle cell trait

OBJECTIVE

Type 2 diabetes (T2D)-related vascular dysfunction and hemorheological abnormalities could possibly be amplified by sickle cell trait (SCT). These alterations could potentially increase the risk of vascular complications in individuals with combined T2D and SCT. Therefore, this study used a mouse model to determine whether vascular function and blood rheology were more severely altered in combined T2D and SCT than in T2D or SCT alone.

METHODS

Townes transgenic mice with or without SCT received a 12-week high fat high sucrose or standard diet to create models of combined T2D-SCT, T2D, SCT, and controls. Pressure-induced vasodilation (PIV) and sodium nitroprusside (SNP)-mediated vasodilation in-vivo, and hemorheological parameters were measured.

RESULTS

No significant differences in blood viscosity, hematocrit, erythrocyte deformability, or PIV were observed between the control and T2D mice, or the control and SCT mice. However, blood viscosity, erythrocyte deformability, and PIV were significantly altered in the T2D-SCT mice compared to the control mice. There were no differences in SNP response between the groups.

CONCLUSIONS

Although neither T2D nor SCT alone had significant effects on blood rheology parameters or vascular function, combined T2D-SCT mice had significantly altered blood rheology and significantly impaired vascular function.

Risk Factors in Central Retinal Vein Occlusion and Activated Protein C Resistance

Introduction

Central retinal vein occlusion (CRVO) tends to be a disease of older individuals, with some known major risk factors, and activated protein C resistance seems to be one of the causes in younger patients. In this study, we reviewed risk factors including activated protein C resistance in a series of patients with CRVO.

Methods

Twenty-four patients with a diagnosis of CRVO presenting either acutely or for a follow-up visit during the study period, were enrolled. Ages ranged between 31 and 83 years (mean 59.7). The risk factors, presence of ischemia, the results of biochemical serological and hematological tests, especially activated protein C resistance (APC-R), were analysed.

Results

In 17 patients (71%) one or more of the following risk factors existed: hypertension, diabetes, oral contraceptive usage, family history of thrombosis, and previous operation. In 40% of the eyes, there were ischemic changes. Serum triglycerides were high in 4 of 21 patients (19%) and cholesterol and urea were high in 10 of 21 patients (19%). APC-R was found in 6 out of 24 patients (25%).

Conclusions

Besides known predisposing factors like hypertension, diabetes, glaucoma and hyperlipidemia, APC-R seems to be a risk factor for CRVO at all ages.

Increased Fibrinogen to Albumin Ratio in Ischemic Retinal Vein Occlusions

Purpose

To demonstrate the relationship between ischemia and plasma fibrinogen and serum albumin levels in cases of retinal vein occlusion (RVO).

Methods

This study included 44 patients with central RVO (CRVO), 68 patients with branch RVO (BRVO), and 54 age- and sex-matched controls, for a total of 166 subjects. All of the subjects underwent full ophthalmologic examinations and complete physical examinations, including a detailed medical history and blood count, and biochemical parameters.

Results

The mean fibrinogen to albumin ratios were 92.5 ± 36.1 for the patients with CRVO, 84.5 ± 31.5 for the patients with BRVO, and 68.4 ± 12.2 for the control group. Overall, the patients with CRVO and patients with BRVO with ischemia had higher fibrinogen to albumin ratios and higher fibrinogen levels. Moreover, significant positive correlations were found between ischemia and the fibrinogen to albumin ratio (r = 0.732, p = 0.001) and the fibrinogen level (r = 0.669, p = 0.001).

Conclusions

The fibrinogen to albumin ratio is significantly associated with ischemic RVO. Instead of complicated and invasive methods, such as a retinal angiogram, the fibrinogen to albumin ratio could be a useful initial diagnostic test to predict ischemia in RVO.

No evidence for thrombophilia in patients with retinal venous occlusion: a systematic GRADE-based review

Retinal venous occlusion represents a common retinal disorder that untreated often leads to severely reduced vision. While general risk factors for vascular disease are known to increase the risk of an event, the role of thrombophilia is controversial. The purpose of this systematic review was to evaluate the evidence for thrombophilia investigation in patients presenting with retinal venous occlusion. Eligible studies were identified by a MESH-based search in PubMed 11-13 of March 2015. The level of evidence was stated according to the guidelines published by the GRADE working group using three levels for quality of evidence: high, moderate and low. A total of 118 studies relating to the study question were identified. After excluding case stories, commentaries, cross-sectional studies and reviews/expert opinions, 28 original papers and two meta-analyses were included in the final qualitative synthesis. The majority of studies were small case-control studies, and only one large cohort study was identified. No randomized controlled trials were retrieved. All the studies were categorized as low quality of evidence. Systematic thrombophilia screening in patients presenting with retinal venous occlusion cannot be recommended.

Impact of Retinal Vein Occlusion on Stroke Incidence: A Meta-Analysis

Background

Considerable controversy exists on the association between retinal vein occlusion (RVO) and stroke risk. Therefore, we conducted a meta‐analysis to assess the relationship between RVO and stroke risk.

Methods and Results

PubMed, EMBASE, and the Cochrane library databases were searched for cohort studies with data on RVO and stroke risk. Studies that reported adjusted relative risks (RRs) with 95% CIs of stroke associated with RVO were included. Stratified analyses were conducted according to key characteristics. A total of 5 articles including results from 6 prospective cohort studies with 431 cases of stroke and 37 471 participants were included in the meta‐analysis. Overall, after adjustment for established cardiovascular risk factors, participants with RVO at baseline were considerably more associated with a greater incidence of stroke risk (combined RR: 1.50, 95% CI: 1.19–1.90), compared to participants without RVO. The results were more pronounced for stroke (RR: 1.72, 95% CI: 1.24–2.37) in the stratified with a stroke history. The risk of stroke was nonsignificant in male subjects (RR: 1.20, 95% CI: 0.96–1.49) and in female subjects (RR: 0.93, 95% CI: 0.64–1.34). The presence of both central RVO (RR: 1.90, 95% CI: 1.46–2.48) and branch RVO (RR: 1.79, 95% CI: 1.18–2.72) was associated with increased risk of stroke. Stratifying by age, the associations between RVO and risk of stroke were similar between the age range in the cohorts that ranged from 50 to 59 years and 60 to 69 years.

Conclusions

Exposure to RVO was associated with an increased risk of stroke, especially in subjects aged between 50 and 69 years. Future studies on the effect of RVO treatment and modifiable risk factor reduction on stroke risk in RVO patients are warranted.

Erythrocyte oxidative stress is associated with cell deformability in patients with retinal vein occlusion

Essentials Retinal vein occlusion (RVO), characterized by blood hyperviscosity, has an unclear pathogenesis. We aimed to find out if hemorheological profile is altered by oxidative stress in RVO patients. Red blood cell (RBC) oxidative stress is associated to whole blood viscosity and RBC deformability. Reactive oxygen species alter RBC membrane rigidity, playing a key role in RVO pathogenesis.

SUMMARY

Background Retinal vein occlusion (RVO) is characterized by vision loss resulting from hypoperfusion and hypoxia of the retina. RVO pathogenesis is not yet fully understood, although blood hyperviscosity has been observed. Erythrocyte deformability plays a key role in determining blood viscosity, and it is critical to microvascular perfusion and oxygen delivery. It has been shown that oxidative stress-induced erythrocyte membrane fluidity alterations are linked to the progression of cardiovascular diseases. Objectives To determine whether erythrocytes from RVO patients show signs of oxidative stress, and whether this condition can modify the hemorheologic profile in these patients. Patients and Methods We analyzed the entire hemorheologic profile and erythrocyte oxidative stress - reactive oxygen species (ROS) production and membrane lipid peroxidation - in 128 RVO patients and 128 healthy subjects, matched for age and sex. Fluorescence anisotropy was used to evaluate the fluidity of erythrocyte membranes. Results In RVO patients, erythrocyte oxidative stress was present and positively correlated with whole blood viscosity and erythrocyte deformability. Multivariate linear regression analysis after adjustment for age, cardiovascular risk factors, medications, leukocyte number and mean corpuscular volume indicated that erythrocyte-derived ROS and erythrocyte lipid peroxidation were significantly and positively correlated with erythrocyte membrane viscosity and deformability. Moreover, in vitro experiments demonstrated that ROS have a key role in erythrocyte membrane fluidity. Conclusions Our findings indicate that erythrocyte oxidative stress plays a key role in the pathogenesis of RVO, and pave the way to new therapeutic interventions.

Retinal vascular occlusion: a window to diagnosis of familial and acquired thrombophilia and hypofibrinolysis, with important ramifications for pregnancy outcomes

Aim

Our specific aim was to document the pathoetiologic importance of thrombophilia among females presenting with severe ischemic retinal vein (RVO) or retinal artery (RAO) occlusion, without typical risk factors, and to emphasize that the ophthalmologists’ diagnosis of thrombophilia has important diagnostic and therapeutic downstream ramifications for nonocular thrombosis, including reproductive outcomes.

Methods

We evaluated familial and acquired thrombophilia in 60 females with RVO (central RVO, n=52; branch RVO, n=8) and 16 with RAO (central RAO, n=11; branch RAO, n=5). They were referred by retinologists, without typical risk factors for RVO/RAO and/or severe ocular ischemic presentation. We focused on extraocular thrombotic events, particularly pregnancy complications, including unexplained spontaneous abortion, pre-eclampsia–eclampsia. Thrombophilia measurements in the 76 females were compared with 62 healthy normal females without ocular vascular occlusions (OVOs).

Results

The 76 females with OVO were more likely than 62 normal female controls to have high homocysteine (24% vs 0%, P<0.0001), high anticardiolipin antibody (immunoglobulin M, 17% vs 3%, P=0.012), high (>150%) factor VIII (42% vs 11%, P<0.0001), and high (>150%) factor XI (22% vs 4%, P=0.004). Of the 76 females, 26 (34%) had ≥1 spontaneous abortion; 17 (22%) had ≥2 spontaneous abortions and/or pre-eclampsia–eclampsia. Compared to 62 healthy female controls, these 17 females with pregnancy complications had high homocysteine (29% vs 0%, P=0.0003), high anticardiolipin antibody immunoglobulin M (24% vs 3%, P=0.02), high factor VIII (38% vs 11%, P=0.02), and were marginally more likely to be heterozygous for the factor V Leiden mutation (19% vs 3%, P=0.058).

Conclusion

In females lacking typical risk factors for retinal vascular occlusion or severely ischemic presentation, by diagnosing thrombophilia as an etiology for OVO, the ophthalmologist opens a window to family screening and preventive therapy, with particular relevance to pregnancy outcomes and venous thromboembolism.

Influence of hemorheological factors on the development of retinal vein occlusion

OBJECTIVE

The aim of this article was to present the influence of hemorheological factors on appearance of Retinal Vein Occlusion (RVO). Article explains which factors predispose to the occurrence of RVO.

STUDY SELECTION

Data presented in the article were collected from both review articles and research articles as well as other sources concerning hemorheology, pharmacology and ophthalmology.

RESULTS

Appearance of RVO is connected with blood viscosity and hemorheological parametres like aggregation of red blood cells, deformability of red blood cells, fibrinogen concentrations and haematocrit, and platelet activity. In the pathogenesis of retinal vein occlusion other risk factors were also indicated: age, systemic diseases and smoking. Such correlation has been indicated in numerous researches which were conducted over the last years. RVO is usually accompanied by macular oedema. RVO may successfully be treated using intravitreal dexamethasone implant.

CONCLUSION

Quick diagnosis and therapy create a possibility for successful treatment. Corticosteroid positive influence on visual acuity improvement has been indicted in two randomized, double-blind controlled studies - CRUISE and BRAVO. In both studies, the improvement of vision has been accompanied by a significant reduction of oedema in the vicinity of macula, reflected in the central retinal thickness.

Central Retinal Vein Occlusion Resolving After Orbital Decompression in Thyroid Eye Disease

A 49-year-old male presented with proptosis and was found to have optic nerve edema with peripapillary hemorrhages. Diagnostic testing showed a suppressed thyroid-stimulating hormone. CT orbits showed homogenous tendon-sparing enlargement of the medial and inferior rectus muscles, characteristic of thyroid eye disease. Intravenous methylprednisolone was administered given the concern for compressive optic neuropathy. He initially had improvement of his symptoms, so orbital decompression was deferred. Subsequently he presented with worsening diplopia and right proptosis, a new afferent pupillary defect, and a cecocentral visual field defect. Dilated examination revealed significant optic nerve head edema and diffuse retinal hemorrhages in all 4 quadrants consistent with a central retinal vein occlusion. The patient underwent an urgent 3-wall orbital decompression on the right. Close follow up postoperatively showed resolution of the central retinal vein occlusion and the associated optic disc edema, peripapillary hemorrhages, and macular edema. Orbital decompression is known to improve many manifestations of thyroid eye disease, but this is the first report of orbital decompression resulting in resolution of a central retinal vein occlusion.

[Changes in hemostasis-related parameters of blood and lacrimal fluid in patients with retinal vein occlusion]

High prevalence of retinal vein occlusion in young people as well as treatment complexity and inadequate control of hemostatic parameters of blood and lacrimal fluid determine the significance of relevant research in patients with retinal vascular pathology. The data thus obtained may be useful for disease prognosis, severity evaluation and therapy control. This review is aimed to study hemostasis-related parameters of blood and lacrimal fluid in such patients.

Seeing through thick and through thin: Retinal manifestations of thrombophilic and hyperviscosity syndromes

The presence of retinal vasculopathy in the absence of typical predisposing factors should suggest a possible underlying hematologic abnormality. In such cases, a systemic investigation may reveal a potentially fatal hypercoagulability or hyperviscosity syndrome. Retinal vein occlusion is the most commonly encountered ophthalmic finding in such syndromes; however, abnormalities of the arterial system, the choroid, and the macula are also possible. Visual symptoms may be the only manifestation of the underlying process, making timely diagnosis by the ophthalmologist critical for both treatment and thrombotic prophylaxis. Moreover, as newer ophthalmic diagnostic technologies arise, there is an increasingly important role for eye physicians in the management of such syndromes.

Diagnostic ramifications of ocular vascular occlusion as a first thrombotic event associated with factor V Leiden and prothrombin gene heterozygosity

AIM

This study aimed to assess the diagnostic ramifications of vascular occlusion of the ocular vein and artery as a first thrombotic event associated with factor V Leiden (FVL) and/or prothrombin gene (PTG) heterozygosity.

METHODS

Patients with ocular vein (n=191) and artery (n=74) occlusion, free of cardioembolic etiologies, were sequentially referred from vitreoretinal specialists for measurement of thrombophilia-hypofibrinolysis and compared to 110 healthy normal controls.

RESULTS

Of the 265 patients, 29 (11%; 17 women, 12 men) of all referred ocular vascular occlusion (OVO) cases were found to be heterozygous for FVL and/or PTG, including 16 with FVL, 12 with PTG, and 1 with both. Of the 29 cases, 16 had central retinal vein occlusion (CRVO), 2 branch retinal vein occlusion (BRVO), 5 nonarteritic anterior ischemic optic neuropathy (NA-AION), 3 retinal artery occlusion (RAO), 2 amaurosis fugax (AF), and 1 had both CRVO and RAO. Of the 16 FVL cases, 15 (94%) had OVO as a first thrombotic event without prior deep venous thrombosis (DVT) or pulmonary embolism (PE); 6 (38%) also had other thrombotic events, including recurrent miscarriage, osteonecrosis, ischemic stroke, and/or ischemic colitis; and 5 (31%) had immediate family members with previous venous thromboembolism (VTE). Of the 12 PTG cases, 9 (75%) had OVO as a first thrombotic event, 5 (42%) experienced VTE other than DVT or PE, and 6 (50%) had immediate family members with VTE. In one patient with both FVL and PTG, DVT occurred before BRVO. Of the 17 women with FVL and/or PTG mutations, 7 (41%) experienced ≥1 miscarriage, 6 (35%) were on estrogen therapy, and 1 (6%) was on clomiphene.

CONCLUSION

Of the 265 patients with OVO, 29 (11%) had FVL and/or PTG, and 83% of these 29 cases presented with OVO as their first thrombotic event. By diagnosing thrombophilia as an etiology for OVO, the ophthalmologist opens a window to family screening and preventive therapy.

Blood viscosity in subjects with normoglycemia and prediabetes

OBJECTIVE

Blood viscosity (BV) is higher in diabetic patients and might represent a risk factor for the development of insulin resistance and type 2 diabetes. However, data in subjects with normal glucose or prediabetes are missing. In the current study, we evaluated the relationship between BV and blood glucose in subjects with normal glucose or prediabetes.

RESEARCH DESIGN AND METHODS

Enrolled subjects were divided into three groups according to blood glucose: group A (n = 74), blood glucose <90 mg/dL; group B (n = 96), blood glucose ranging from 90 to 99 mg/dL; and group C (n = 94), blood glucose ranging from 100 to 125 mg/dL. BV was measured at 37°C with a cone-plate viscometer at shear rates ranging from 225 to 22.5 s(-1).

RESULTS

Blood pressure, blood lipids, fibrinogen, and plasma viscosity were similar in the three groups. BMI and waist circumference were significantly increased in group C. Hematocrit (P < 0.05) and BV (P between 0.01 and 0.001) were significantly higher in groups B and C compared with group A. Blood glucose was significantly and inversely correlated with HDL cholesterol and directly with BMI, waist, hematocrit (r = 0.134), and BV (from 225 s(-1) to 22.5 s(-1); r ranging from 0.162 to 0.131). BV at shear rate 225 s(-1) was independently associated with blood glucose.

CONCLUSIONS

The current study shows a direct relationship between BV and blood glucose in nondiabetic subjects. It also suggests that, even within glucose values considered completely normal, individuals with higher blood glucose levels have increased BV comparable with that observed in subjects with prediabetes.

The ABCs of RVO: a review of retinal venous occlusion

Retinal vein occlusions are important causes of loss of vision; indeed, they are the second most common retinal vascular disease, following diabetic retinopathy. For this reason alone, primary eye-care providers must be well versed in diagnosis and management. Risk factors, though not universally agreed upon, include but are not limited to advancing age, systemic hypertension, arteriolarsclerosis, diabetes, hyperlipidaemia, blood hyperviscosity, thrombophilia, ocular hypertension and glaucoma. Typically, visual loss is secondary to macular oedema and/or retinal ischaemia. Treatment modalities have included observation, systemic thrombolysis and haemodilution, radial optic neurotomy, chorioretinal anastomosis, vitrectomy, laser photocoagulation and intravitreal injection of anti-inflammatory and, most recently, anti-vascular endothelial growth factors.

Mortality in patients with central retinal vein occlusion

PURPOSE

To assess mortality in patients with central retinal vein occlusion (CRVO).

DESIGN

Registry-based cohort study.

PARTICIPANTS AND CONTROLS

Four hundred thirty-nine photographically verified CRVO patients and a control cohort of 2195 unexposed subjects matched by age and gender and alive on the date CRVO was diagnosed in the corresponding case.

METHODS

Data from nationwide registries were used to compare mortality rates in CRVO patients with a control cohort over a mean follow-up of 5.1 years for cases and of 5.7 years for controls.

MAIN OUTCOME MEASURES

Hazard ratios (HRs) obtained by Cox regression and standardized mortality ratios (SMRs) stratified by age and gender served as measures of relative mortality risk.

RESULTS

Mortality was higher in patients with CRVO (HR, 1.45; 95% confidence interval [CI], 1.19-1.76) than in the control cohort, adjusted for age, gender, and time of diagnosis. Mortality was comparable between the 2 groups (HR, 1.19; 95% CI, 0.96-1.46) when adjusting for overall occurrence of cardiovascular disease and diabetes. Subgroup analysis found that the age-stratified mortality rate was increased significantly in the total group of men (SMR, 1.27; 95% CI, 1.03-1.56) and in women 60 to 69 years of age (SMR, 1.94; 95% CI, 1.22-3.08).

CONCLUSIONS

Central retinal vein occlusion was associated with an overall increase in mortality compared with controls that was attributed statistically to cardiovascular disorders and diabetes. We recommend treatment of hypertension and diabetes, if present, and referral of patients found to have CRVO who are not already being treated by a primary care physician.

Therapeutic potential of intravitreal pharmacotherapy in retinal vein occlusion

Retinal vein occlusion (RVO) is the most common visually disabling disease affecting the retina after diabetic retinopathy. Although the disease entity has long been known, its management is still controversial. Macular edema is the main reason for decreased visual acuity (VA) in this retinal vascular disorder. Recently the vitreous cavity has increasingly been used as a reservoir of drugs for the direct treatment of macular edema through intravitreal injection route. The most widely injected drugs so far have been triamcinolone acetonide (TA) and bevacizumab. The objective of this review is to evaluate the evidence and discuss the rationale behind the recent suggestions that intravitreal pharmacotherapy by corticosteroids and anti-vascular endothelial growth factors may be useful in the treatment of retinal vein occlusion.

Comorbidity in patients with branch retinal vein occlusion: case-control study

OBJECTIVES

To evaluate comorbidity before and after the diagnosis of branch retinal vein occlusion to determine whether it is a consequence of arterial thickening and therefore could serve as a diagnostic marker for other comorbidities and to evaluate the risk factors for the development of such occlusion.

DESIGN

Case-control study with prospective follow-up data from Danish national registries.

SETTING

Four secondary referral centres covering about 80% of the Danish population (4.4 million).

PARTICIPANTS

1168 patients with photographically verified branch retinal vein occlusion and 116,800 controls alive and aged ≥ 40 when the occlusion was diagnosed in the corresponding case.

MAIN OUTCOME MEASURES

The risk of comorbidity 10 years and 1 year before the diagnosis of branch retinal vein occlusion and the incident comorbidity in a mean period of seven years after the diagnosis, with odds ratios and incidence rate ratios adjusted for age, sex, and year of diagnosis.

RESULTS

Risk factors present 10 years and 1 year before the diagnosis of branch retinal vein occlusion included peripheral artery disease (odds ratio 1.83, 95% confidence interval 1.14 to 2.95), diabetes (1.74, 1.40 to 2.17) and arterial hypertension (2.16, 1.86 to 2.51). After the diagnosis, patients had an increased risk of developing arterial hypertension (incidence rate ratio 1.37, 95% confidence interval 1.15 to 1.57), diabetes (1.51, 1.17 to 2.04), congestive heart failure (1.41, 1.12 to 1.68), and cerebrovascular disease (1.49, 1.27 to 1.76).

CONCLUSION

Diabetes, hypertension, and peripheral artery disease are associated with an increased risk of developing branch retinal vein occlusion up to a decade later. Branch retinal vein occlusion was associated with an increased risk of subsequently developing hypertension, diabetes, congestive heart failure, and cerebrovascular disease, emphasising the importance of preventive initiatives. These results fit the assumption that branch retinal vein occlusion is a consequence of arterial thickening and that the arteriovenous crossing signs that precede it are hallmarks of arterial disease.

Red blood cell phosphatidylserine exposure is responsible for increased erythrocyte adhesion to endothelium in central retinal vein occlusion

BACKGROUND

Retinal vein occlusion (RVO) is a common cause of permanent loss of vision. The pathophysiology is uncertain, although enhanced erythrocyte aggregation and blood hyperviscosity have been observed. Increased red blood cell (RBC) adhesion has been associated with vascular complications in several diseases, such as sickle cell anemia, diabetes mellitus or polycythemia vera.

OBJECTIVES

To measure RBC adhesion to endothelial cells in RVO and to explore the molecular basis of the adhesion process.

PATIENTS AND METHODS

We assessed RBC adhesion to endothelial cells and adhesion molecule expression among 32 patients with RVO. Patients with disease known to alter RBC adhesion were excluded (n = 8), and further investigation was conducted in 20 patients with central retinal vein occlusion (CRVO) and four patients with retinal artery occlusion (RAO), compared with 25 normal subjects.

RESULTS

Under static conditions, adhesion of CRVO RBC was increased (135 ± 7 × 10(2) mm(-2)) compared with RAO RBC (63 ± 5 × 10(2) mm(-2)) (P < 0.01) and normal control RBC (37 ± 3 × 10(2) mm(-2)) (P < 0.001). Under flow conditions, CRVO RBC adhered in greater numbers than normal RBC (P < 0.001). Phosphatidylserine (PS) expression on CRVO RBC was 2.4-fold higher than controls and correlated with RBC adhesion (P = 0.001). In static conditions, specific antibodies against PS receptor and annexin V inhibited RBC adhesion. In flow conditions, the inhibitory effect was in the same range with antibodies but was 2-fold higher with annexin V.

CONCLUSION

Increased CRVO RBC adhesion is mediated by PS RBC and endothelial PS receptor. This phenomenon may be one of the factors responsible for CRVO.

Management of macular edema secondary to central retinal vein occlusion: an evidence-based

Retinal vein occlusions are common retinal vascular disorders with the potential for significant vision-related morbidity. Retinal vein occlusions are classified as either branch retinal vein occlusion (BRVO), central retinal vein occlusion (CRVO), or hemiretinal vein occlusion (HRVO) based on the specific occlusion site. Decreased vision in patients afflicted with CRVO may result from retinal ischemia and/or the accumulation of fluid within the center of the retina (macular edema). The Central Vein Occlusion Study (CVOS) Group demonstrated that grid laser photocoagulation is not an effective treatment for decreased vision due to CRVO-related macular edema. Since publication of that report, the standard of care for patients with decreased vision due to CRVO-associated macular edema was observation. However, in the past 5 years, several major randomized controlled clinical trials have investigated new therapeutic modalities for the treatment of macular edema secondary to CRVO. This article aims to provide insight into current evidence-based approaches to the management of macular edema secondary to CRVO. A companion article reviews approaches for the management of macular edema secondary to BRVO.

[SERV clinical practice guidelines: management of retinal vein occlusion. Sociedad Española de Retina y Vitreo]

PURPOSE

A guidelines for the management of retinal vein occlusion is presented. This is necessary because at this moment several therapeutic alternatives have been developed although their role is not yet sufficiently defined.

METHODS

Review of the literature for evidence published up to date. Relevant literature was identified and the level of evidence graded. Evidence was then assessed for consistency, applicability and clinical impact. The information was contrasted with those guides published in other countries.

RESULTS

Taking into account the different options of treatment that are currently used, several modes of action are suggested. The role of the various complementary examinations are discussed and it is recommended that criteria for the treatment are based on clinical, angiographic, and tomographic findings.

CONCLUSIONS

Although there is no overall consensus, these guidelines promote a good standard of clinical practise and provide an update of the management of retinal vein occlusion.

Retinal vein occlusion: evaluation of "classic" and "emerging" risk factors and treatment

Retinal vein occlusion (RVO) is the second most common retinal vein disease and an important cause of blindness and visual morbidity. Systemic risk factors are commonly associated with RVO, while unclear it is the role of the thrombophilic and coagulation disorders. To evaluate "classic" and "emerging" risk factors, and to establish a good treatment for RVO. Fifty patients, 31 males and 19 females, with RVO were selected for our study. RVO patients were divided into two groups: those with central retinal vein occlusion (CRVO) and those with branch retinal vein occlusion (BRVO). All patients were subjected to an anamnestic investigation and were tested for thrombophilia, coagulation disorders and hyperlipidemia. Treatment and prophylaxis were evaluated. We have named "classic" the systemic risk factors associated with RVO and "emerging" those risk factors, haemostasis related, not clearly associated with RVO. RVO occurs more commonly in patients aged over 50. "Emerging" risk factors were more frequent in CRVO, "classic" in BRVO. Hyperhomocysteinemia is the most common "emerging" risk factor related to RVO. 71.4% of tested patients had hypercholesterolemia. Treatment with LMWH would appear to be safe and effective, but the small number of patients considered not allow us a definitive evaluation of its efficacy. Although our study has shown the correlation between RVO and the "emerging" risk factors, more studies are necessary to better know the real role of thrombophilic and coagulation disorders in this disease and to determine a specific protocol for the treatment and prophylaxis of RVO.

Clinical progress in impending central retinal vein occlusion

Purpose

Impending central retinal vein occlusion is associated with mild or no loss of vision; however, its progress and vision prognosis have not been clearly defined until now. Therefore, we studied the progress and prognoses in patients with impending central retinal vein occlusion.

Methods

For this study, we selected ten subjects who had been diagnosed with impending central retinal vein occlusion, and we retrospectively reviewed their progress and prognoses.

Results

The average age of the subjects was 31.0 years (18 to 48 years). Eight patients were male and two were female. The average observational period was 5.5 months. Six out of ten subjects were found to have no underlying systemic disease, four subjects had underlying disease. All ten patients were affected unilaterally. When initially tested, the affected eyes showed an average vision of LogMar 0.30. The final vision test revealed an average of LogMar 0.04, which indicates good progress and prognosis. In one patient, retinal hemorrhage and macular edema progressively worsened after the diagnosis, and the patient was treated with radial optic neurotomy.

Conclusions

The cases of impending central retinal vein occlusion that we observed seemed to primarily affect young patients with generally good prognoses. However, in some cases, the degrees of obstruction and hemorrhage increased as time progressed. This suggests that impending central retinal vein occlusion could develop into the prodromal phase of an acute attack.

Radial optic neurotomy for central retinal vein occlusion: results of the Pan-American Collaborative Retina Study Group (PACORES)

OBJECTIVE

To evaluate the complications after radial optic neurotomy (RON) for central retinal vein occlusion (CRVO).

METHODS

Seventy-three consecutive patients (73 eyes) with CRVO who were treated with RON participated in a retrospective, uncontrolled, interventional, multicenter case series at 7 institutions from 6 countries.

RESULTS

In the ischemic CRVO group (n = 53), 32% of eyes had an improvement in best-corrected visual acuity (BCVA) (mean, 5.5 lines), 35.8% had worse BCVA (mean, 6.4 lines), and 32% had BCVA that remained the same after RON. In the nonischemic CRVO group (n = 20), 50% of eyes had an improvement in BCVA (mean, 6.5 lines), 15% had worse BCVA (mean, 4.3 lines), and 35% had BCVA that remained the same after RON. Complications occurred in 71.2% of cases, including cataract in 17 eyes (23.2%), vitreous hemorrhage in 16 eyes (20.5%), persistent macular edema in 15 eyes (20.5%), neovascular glaucoma in 7 eyes (9.5%), anterior segment neovascularization in 5 eyes (6.8%), retinal detachment in 3 eyes (4.1%), and phthisis bulbi, choroidovitreal neovascularization, central retinal artery perforation, and optic nerve atrophy in 1 eye (1.3%) each.

CONCLUSIONS

RON may improve visual acuity in some eyes with CRVO, but complications are common. In our series, surgery by itself did not seem to improve the outcome of CRVO when compared with its natural history.

Hemorheological disorders in diabetes mellitus

The objective of the present study is to review hemorheological disorders in diabetes mellitus. Several key hemorheological parameters, such as whole blood viscosity, erythrocyte deformability, and aggregation, are examined in the context of elevated blood glucose level in diabetes. The erythrocyte deformability is reduced, whereas its aggregation increases, both of which make whole blood more viscous compared to healthy individuals. The present paper explains how the increased blood viscosity adversely affects the microcirculation in diabetes, leading to microangiopathy.

Increased plasma asymmetric dimethylarginine (ADMA) levels in retinal venous occlusive disease

BACKGROUND

We investigated the levels of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA), as well as homocysteine and cysteine thiols, in a cohort of subjects affected by retinal vein occlusion (RVO) disease.

METHODS

Capillary electrophoresis analysis was performed in both RVO subjects (n=54) and in a control group (n=32).

RESULTS

No differences were found between controls and patients; however, after categorisation for RVO type, central RVO (CRVO) patients showed higher levels of ADMA (0.710+/-0.139 micromol/L) than controls (0.635+/-0.117 micromol/L) and branch RVO patients (0.642+/-0.096 micromol/L). Moreover, cysteine plasma levels were also significantly higher in CRVO patients than in controls (265.8+/-46.9 vs. 226.7+/-51.9 micromol/L, p<0.01), while homocysteine plasma concentration was more or less identical in all groups.

CONCLUSIONS

We hypothesise that the elevated levels of cysteine in CRVO patients may post-translationally inhibit dimethylarginine dimethylaminohydrolase enzyme activity, as already described for homocysteine, thus contributing to the accumulation of ADMA in this patient group.

Mortality in Patients with Branch Retinal Vein Occlusion

PURPOSE

To assess the impact of branch retinal vein occlusion (BRVO), a condition related to arteriolar wall thickening, as a prognostic marker of mortality.

DESIGN

Long-term follow-up study comparing cases with background population.

PARTICIPANTS

Patients diagnosed with BRVO.

METHODS

Diagnosis of BRVO confirmed by fundus photographic records including color diapositives and fluorescein angiograms.

MAIN OUTCOME MEASURES

Observed and expected numbers of deaths determined from comprehensive civic records in cases compared with the background population (5.4 million).

RESULTS

Branch retinal vein occlusion was found in 329 patients (173 women, 156 men) born between 1902 and 1956, who were 39 to 91 years old when diagnosed between 1973 and 1998. Follow-up was concluded on July 8, 2004, when 144 deaths were recorded in patients (74 women, 70 men), compared with an expected number of 145.5 deaths in the background population (standardized mortality rate, 0.99; 95% confidence interval, 0.84-1.16). Stratified analyses revealed no significant effect of age, gender, or time of diagnosis.

CONCLUSIONS

In this study of 329 patients with BRVO, we found no significant difference in mortality between patients and the background population. An association between BRVO and cardiovascular/cerebrovascular risk factors has previously been documented in cross-sectional studies. The contrasting outcome in this longitudinal study may have been influenced by interventions instituted after the diagnosis of BRVO was made and by preferential survival before the diagnosis of BRVO of the more fit patients with the necessary precursor condition of having arteriovenous nicking, which is more prevalent in subjects with diabetes and hypertension.

Is elevated level of soluble endothelial protein C receptor a new risk factor for retinal vein occlusion?

BACKGROUND

To evaluate the systemic and thrombophilic risk factors for retinal vein occlusion (RVO) and to determine whether the elevated level of soluble endothelial protein C receptor (sEPCR) is a risk factor for thrombosis.

METHODS

In this case-control study, 56 patients with central RVO (CRVO), 26 patients with branch RVO (BRVO) and 78 healthy sex- and age-matched subjects were enrolled. Following ophthalmological examination, venous blood was analysed for glucose, lipid profile, lipoprotein (a), homocysteine, activated partial thromboplastin time, fibrinogen, factor VIII, protein C activity, protein S activity, activated protein C resistance, antithrombin III activity, lupus anticoagulant, anti-cardiolipin antibody, anti-phospholipid antibody, sEPCR, factor V Leiden mutation and prothrombin G20210A mutation.

RESULTS

Apart from hypertension, glaucoma, lipoprotein (a), homocysteine and factor VIII, elevated levels of sEPCR were found to be a risk factor for CRVO (odds ratio, 1.02; 95% confidence interval, 1.007-1.028; P = 0.001). Patients with CRVO had significantly higher levels of sEPCR than those with BRVO and controls (respectively, 160.1 +/- 83.8, 116.8 +/- 65.2 and 111.3 +/- 60.5; P = 0.005). Moreover, 39% of patients with CRVO had levels of sEPCR more than 200 ng/mL, and only 5% of controls and 11% of patients with BRVO had similar high levels.

CONCLUSIONS

Besides known classical risk factors, elevated levels of sEPCR seem to be an important candidate risk factor for especially CRVO.

Venenastverschluss und Abduzensparese bei Protein-S-Mangel

BACKGROUND

Protein S deficiency, which exists in 0.7% of the population, is a risk factor for retinal vein branch occlusions and is inherited in an autosomal dominant manner.

METHODS

A genealogical study was carried out on three generations of one family who exhibited different venous occlusions and subsequent complications.

RESULTS

Four members of the family, spanning three generations, suffered from complications of venous thrombosis. In the first generation a great uncle died of complications from a deep leg venous thrombosis. In the second generation, the mother underwent a venous branch thrombosis at the age of 41 with a protein S activity of 18%. Subsequently, a palsy of the N. abducens developed with multiple cerebral lesions (presumably post-thrombotic) in the MRI. Fluorescein angiography showed a typical picture of a venous branch occlusion which had been treated by laser. In the third generation, the 16-year-old daughter developed iliac venous thrombosis and a pulmonary embolism with a protein S activity of 0%. The fluorescein angiography showed distinctively engorged veins. A 28-year-old daughter, with a protein S activity of 16%, remained asymptomatic, although fluorescein angiography demonstrated engorged veins. Protein C activity and APC resistance of all family members were normal. The chromosomal analysis of the family members revealed no morphological aberrations.

CONCLUSION

Protein S deficiency increases the risk of congenital thrombosis in young and middle-aged heterozygous individuals.

Central retinal vein occlusion in sickle cell disease

Central retinal vein occlusion has not been reported previously in patients with sickle cell anemia. We describe the case of a 31-year-old man with sickle cell anemia who developed this complication. The search for risk factors for central retinal vein occlusion in this young patient revealed protein S deficiency and a history of iron deficiency. He was treated with anticoagulation therapy, and his vision improved gradually.