Assessment of Serum Atherogenic Indices and Insulin Resistance in Retinal Vein Occlusion

Objectives

This study aimed to investigate serum atherogenic indices as novel cardiovascular risk factors associated with retinal vein occlusion (RVO).

Materials and Methods

This retrospective case-control study included 57 patients with newly diagnosed RVO whose plasma lipid profile (low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], total cholesterol [TC], and triglycerides [TG]) and insulin resistance were examined. Serum atherogenic indices (LDL-C/HDL-C, TC/HDL-C, TG/HDL-C, and non-HDL-C/HDL-C ratios) and presence of insulin resistance were compared between the patients and 63 healthy subjects. Cut-off values were determined by receiver operating characteristic curve analysis.

Results

The mean age of the RVO patients was 63.7±9.4 years. Plasma levels of LDL-C, HDL-C, TC, and TG showed no significant difference between the patient and control groups (p>0.05). However, LDL-C/HDL-C, non-HDL-C/HDL-C, and TC/HDL-C ratios were higher in the RVO group compared to healthy subjects (p=0.015, p=0.036, and p=0.015, respectively). Fasting insulin concentrations, plasma insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) index were higher in the RVO patients compared to controls (p=0.003, p=0.001, and p=0.001, respectively).

Conclusion

LDL-C/HDL-C, TC/HDL-C, and non-HDL-C/HDL-C ratios were found to be increased in RVO. Compared to the traditional plasma lipid profile, serum atherogenic indices were found to be superior predictors of RVO development. Measurement of HOMA-IR index should be taken into consideration in the evaluation of insulin resistance. High serum atherogenic indexes in RVO patients reveal the need to take precautions against the risk of cardiovascular disease and stroke.

SERUM LEVELS OF ANTIBODIES AGAINST OXIDATION-SPECIFIC EPITOPES ARE DECREASED IN PATIENTS WITH RETINAL VEIN OCCLUSION

PURPOSE

Oxidative stress and inflammation have been implicated in the development of retinal vein occlusion (RVO). Oxidation-specific epitopes (OSEs) represent products of oxidative stress that can trigger vascular inflammation and thrombosis. Natural occurring antibodies have been shown to bind oxidation-specific epitopes thereby inhibiting their inflammatory potential and promoting their removal.

METHODS

This prospective cross-sectional study included 270 patients with RVO and 81 in-hospital control patients. We measured three types of serum levels of oxidation-specific epitope-specific immunoglobulin M and immunoglobulin G antibodies (anti-copper-oxidized LDL [CuOx-LDL], antiphosphocholine [PC], anti-malondialdehyde-modified LDL [MDA-LDL]). History of arterial hypertension, hyperlipidemia, myocardial infarction, diabetes mellitus, stroke, smoking status, and several laboratory parameters were determined to control for potential confounders.

RESULTS

Compared with controls, patients with RVO had significantly lower levels of immunoglobulin M and immunoglobulin G antibodies against CuOx-LDL and PC, and significantly lower levels of immunoglobulin G but not immunoglobulin M antibodies against MDA-LDL. The association between RVO patients and lower levels of these antibodies prevailed upon multivariable adjustment.

CONCLUSION

These prospective data show that antibodies against oxidation-specific epitope are lower in patients with RVO compared with control patients and support the concept that oxidative stress and inflammation play key roles in the development and subsequent complications in RVO.

ASSOCIATION BETWEEN PLATELET INDICES AND RETINAL VEIN OCCLUSION: A Systematic Review and Meta-Analysis

PURPOSE

Platelet count, mean platelet volume, platelet distribution width, and plateletcrit are standard indices of platelet activation that have been studied in retinal vein occlusion (RVO) and its subtypes: branch retinal vein occlusion and central retinal vein occlusion. This systematic review and meta-analysis aimed to assess the association between these platelet parameters and RVO.

METHODS

We searched for studies investigating the association between these platelet indices and RVO in multiple online databases from inception to August 2020. Mean differences and the associated confidence intervals were obtained and calculated for each included study and pooled using random-effects inverse variance modeling. Meta-regression was used to explore interstudy and intrastudy heterogeneity.

RESULTS

Thousand three hundred and twenty-five unique studies were screened, from which 24 studies encompassing 2,718 patients were included. Mean platelet volume and platelet distribution width were significantly elevated in RVO, with pooled mean differences of 0.45 fL (95% CI 0.24-0.66, P < 0.0001) and 1.43% (95% CI 0.57-2.29, P = 0.0011), respectively. Platelet count and plateletcrit were not significantly associated with RVO. Mean platelet volume was also independently elevated in branch retinal vein occlusion and central retinal vein occlusion.

CONCLUSION

Mean platelet volume and platelet distribution width are significantly elevated in RVO. Further research is required to explore the independence and potential prognostic significance of these associations.

Comparison of systemic conditions at diagnosis between central retinal vein occlusion and branch retinal vein occlusion

Objective

To compare systemic conditions at the time of diagnosis between patients with central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO).

Design

This study included patients diagnosed with CRVO or BRVO between February 2009 and August 2017 at three branch hospitals of Hallym University Medical Center. Demographic and anthropometric variables, systemic comorbidity profiles, and laboratory findings at diagnosis were collected from a clinical data warehouse system, and were compared between the CRVO and BRVO groups.

Result

Four hundred and seventeen patients with CRVO and 1,511 patients with BRVO were included. The mean age was 61.8 ± 13.9 years, which was comparable between two groups (P = .332). Female proportion was higher in the BRVO group (55.0%) than in the CRVO group (48.0%; P = .013). Diabetes mellitus (P = .017) and chronic kidney disease (P = .004) were more prevalent in the CRVO group. Serum homocysteine level was abnormally high in 23.5% of CRVO patients and in 8.4% of BRVO patients (P < .001). Blood urea nitrogen and serum creatinine levels were abnormally elevated in more subjects with CRVO (P = .002).

Conclusion

CRVO is associated with higher prevalence of diabetes mellitus and chronic kidney disease, as well as with elevated serum homocysteine level. These results might suggest a difference between the pathophysiologies of CRVO and BRVO.

Mean platelet volume and central retinal vein occlusion in hypertensive patients

OBJECTIVE

To study the relationship between mean platelet volume (MPV) and central retinal vein occlusion (CRVO) in hypertensive patients.

DESIGN

Hospital-based, retrospective, case control design.

PARTICIPANTS

The sample group consisted of 100 patients with a known history of hypertension and who are diagnosed with CRVO. The control group consisted of 100 age and sex-matched patients with the sample group and who had a sole history of hypertension without any other systemic diseases and the best corrected visual acuity of 20/20 in both the eyes.

METHODS

CRVO was diagnosed based on clinical examination. All cases and control subjects underwent complete ocular examination. MPV, platelet count, hemoglobin, white blood cell count and hematocrit parameters were recorded for both groups. The data of patients with CRVO was compared with the control subjects. Confidence interval was set at 95% with a P-value of < 0.05.

RESULTS

MPV was significantly higher among hypertensive cases diagnosed with CRVO when compared with the hypertensive control group (8.059 ± 0.016, 7.442 ± 0.15 fL respectively; P < 0.001). The platelet count was lower in the control group, but the difference was not significant. The systolic blood pressure was significantly higher in the sample group.

CONCLUSIONS

Our results demonstrated that MPV values were significantly higher in patients with CRVO, suggesting that increased MPV may contribute to the development of CRVO.

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.

Retinal vein occlusion: A form of venous thrombosis or a complication of atherosclerosis?

Previous studies have shown an increased risk of retinal vein occlusion (RVO) in patients with hypertension, hypercholesterolemia and diabetes mellitus. Literature on the association between thrombophilic factors and RVO consists of small studies and case reports. The objective was to determine the relationship between thrombophilic risk factors and RVO. Thrombophilic risk factors analyzed were hyperhomocysteinemia, MTHFR gene mutation, factor V Leiden mutation, protein C and S deficiency, antithrombin deficiency, prothrombin gene mutation, anticardiolipin antibodies and lupus anticoagulant. For all currently known thrombophilic risk factors odds ratios for RVO were calculated as estimates of relative risk. The odds ratios were 8.9 (95% CI 5.7 –13.7) for hyperhomocysteinemia, 3.9 (95% CI 2.3 – 6.7) for anticardiolipin antibodies, 1.2 (95% CI 0.9 –1.6) for MTHFR, 1.5 (95% CI 1.0 – 2.2) for factor V Leiden mutation and 1.6 (95% CI 0.8 – 3.2) for prothrombin gene mutation. In conclusion, regarding thrombophilic risk factors and RVO there is only evidence for an association with hyperhomocysteinemia and anticardiolipin antibodies, factors that are known as risk factors for venous thrombosis as well as for arterial vascular disease. The minor effect of factor V Leiden mutation and the protrombin gene mutation (risk factors for venous thrombosis only) suggests that atherosclerosis might be an important factor in the development of CRVO.

Impaired fibrinolysis in retinal vein occlusion: a role for genetic determinants of PAI-1 levels

Few and contrasting data are available on the presence of a thrombophilic state in patients with retinal vein occlusion (RVO), and we have previously demonstrated a role of elevated PAI-1 activity as a risk factor for this condition. The present study was undertaken to investigate whether PAI 4G/5G and ACE I/D polymorphisms are independent risk factors for RVO and whether they account for elevated PAI-1 activity levels. We studied 112 RVO patients (52 males and 60 females; range 18–83 years; median age 60 years) and 112 healthy subjects (52 males and 60 females; range 20–84 years; median age 57 years). PAI-1 activity was determined by a chromogenic assay and ACE I/D and PAI-1 4G/5G polymorphisms by polymerase chain reaction (PCR) and restriction length fragment polymorphism (RLFP) methods. Elevated PAI-1 activity (above 95th percentile of the controls) was significantly associated with RVO at multivariate analysis after adjustment for age, sex, traditional cardiovascular risk factors and haemostasis-related risk factors (OR = 4.93, 95% CI 1.70–14.30; p = 0.003).The homozygosity for ACE DD was found to be an independent risk factor for RVO at multivariate analysis (OR = 1.98, 95% CI 1.013.83; p = 0.049), whereas no significant association between homozygosity for PAI-1 4G4G and risk of RVO was observed. Subjects carrying both ACE DD genotype and PAI-1 4G4G genotype showed an increased risk for RVO at multivariate analysis (OR = 4.82, 95% CI 1.89–12.29; p = 0.001). In 45/112 patients without the established risk factors for RVO (hypertension, hypercholesterolemia and diabetes) or characteristics known to be associated to increased PAI-1 activity (overweight, hypertriglyceridemia, and smoking habit) the contemporary presence of ACE DD and PAI-1 4G4G genotype was significantly associated with a risk for RVO (OR = 8.26, 95% CI 1.1857.92; p = 0.034). In conclusion, in our study: 1-indicates that ACE DD genotype is a risk factor for RVO in the whole group of patients, and in the subgroup of patients without the established risk factors for RVO or characteristics influencing the PAI-1 activity, when associated to PAI-1 4G4G genotype, and 2-confirms the role of hypofibrinolysis, documented by high levels of PAI-1 activity, in the occurrence of patients with RVO.

Thrombophilic and cardiovascular risk factors for retinal vein occlusion

BACKGROUND

The role of thrombophilic and cardiovascular risk factors in different manifestations of retinal vein occlusion (RVO), i.e., central or branch RVO, and at different ages is still debated.

AIMS

To evaluate the association between thrombophilic and cardiovascular risk factors and the risk of RVO (overall, separately for central and branch RVO, and at different ages).

METHODS

Case-control study on 313 patients with a first objectively-confirmed RVO (216 central and 97 branch RVO) and 415 healthy individuals.

RESULTS

Antithrombin, protein C or protein S deficiency (adjusted odds ratio [95%CI]: 15.60 [2.01-121]; p=0.009), hyperhomocysteinemia (HHCy; 3.22 [1.38-7.49]; p=0.007), high factor VIII (FVIII) levels (3.08 [1.20-7.89]; p=0.019), factor V Leiden (2.93 [0.97-8.86]; p=0.058) and the presence of at least one cardiovascular risk factor (1.79 [1.00-3.23]; p=0.050) were associated with an increased risk of branch RVO. The association was weaker for central RVO, and limited to HHCy (2.15 [1.09-4.24]; p=0.027) and high FVIII (1.99 [0.90-4.42]; p=0.091). For HHCy, high FVIII and cardiovascular risk factors the association with the risk of RVO was stronger at an age>50years (3.41[1.29-8.99], p=0.013; 2.57[1.00-6.68], p=0.050; and 2.03[1.16-3.56], p=0.013, respectively) than ≤50years (1.93[0.85-4.36], p=0.114; 1.67[0.54-5.12], p=0.371; and 1.22[0.73-2.03], p=0.454, respectively), whereas classic inherited thrombophilia (antithrombin, protein C or protein S deficiencies, factor V Leiden and prothrombin G20210A mutation) was slightly more prevalent at an age≤50years (1.62 [0.76-3.45], p=0.210) than >50years (1.11[0.44-2.79], p=0.833).

CONCLUSIONS

Thrombophilic and cardiovascular risk factors are associated with RVO, particularly branch RVO. The risk of RVO associated with HHCy, high FVIII and cardiovascular risk factors is higher at an older age.

Increased pregnancy-associated plasma protein A in retinal vein occlusion

OBJECTIVE

The aim of this study was to evaluate pregnancy-associated plasma protein A (PAPP-A) levels in patients with retinal vein occlusion (RVO), and to investigate its possible role as a predictive biomarker.

PATIENTS AND METHODS

The study included 26 patients with RVO and 30 age- and gender-matched healthy subjects as controls. PAPP-A levels were measured using an enzyme-linked immunosorbent assay (ELISA) kit. The PAPP-A levels in patients with RVO were compared with those in the control group using the Mann-Whitney U test.

RESULTS

The mean serum PAPP-A levels were 1.27 ± 0.46 mIU/L (mean ± standard deviation) in the RVO group and 1.14 ± 0.11 mIU/L in the control group. There was a significant difference in PAPP-A levels between RVO patients and healthy subjects (p = 0.03). Moreover, in ROC analysis comparing the RVO patients and controls, a cutoff value of 1.126 (AUC: 0.669), specificity of 63.3% and sensitivity of 76.9% were calculated for the RVO patients (p = 0.03).

CONCLUSIONS

Our data seems to support the roles of both thrombosis and atherosclerosis in the development of RVO. It is possible that PAPP-A may be involved in the pathogenesis of venous thrombosis in the retina.

Altered platelet morphological parameters in patients with retinal vein occlusion

OBJECTIVE

The purpose of this work was to investigate whether platelet morphology or functions are altered in retinal vein occlusion (RVO) patients.

PATIENTS AND METHODS

Eighty-three patients with a RVO and eighty-five healthy subjects were included in this prospective study. RVO was diagnosed by ophthalmic fundus examination, and complete ophthalmic evaluations of both eyes were performed. The platelet large cell ratio (PLCR), platelet distribution width (PDW), mean platelet volume (MPV), platelet crit (PCT), and platelet count were determined for each participant.

RESULTS

The MPV, PDW and PLCR were significantly higher in the RVO group than in the control group (MPV: 8.26 ± 1.22 fL vs. 7.41 ± 0.69 fL, respectively, p = 0.006; PDW: 13.43 ± 1.75% vs. 12.19 ± 1.51%, respectively, p = 0.0022; and PLCR: 30.62 ± 4.65% vs. 28.59 ± 4.18%, respectively, p = 0.003). There were no significant differences in the PCT or platelet count between the two groups (253.76 ± 70.87 x 103/µl vs. 248.96 ± 62.44 x 103/µl, respectively p > 0.05; and PCT: 0.24 ± 0.07 % vs. 0.27 ± 0.06%, respectively, p > 0.05).

CONCLUSIONS

We observed that the platelets RVO patients exhibit morphological evidence of hyperreactivity (e.g., a higher MPV, PDW and PLCR). Also, larger platelets are hemostatically more active than small ones and an increased proportion of large platelets is a risk factor for developing RVO.

The role of coagulation disorders in patients with retinal vein occlusion

BACKGROUND

The role of a hypercoagulable state in the pathogenesis of retinal vein occlusion (RVO) has not been conclusively established.

AIM

To analyse the prevalence of thrombophilia in RVO.

DESIGN

Prospective case-control study.

METHODS

All the patients diagnosed with RVO were referred to an Internal Medicine clinic and compared with sex- and age-matched individuals from a population-based cohort. Demographic, clinical and laboratory variables (including a thrombophilia panel) were analysed.

RESULTS

One hundred and seventy patients (93 men and 77 women; 68 ± 11 years) and 170 controls (80 men and 90 women; 67 ± 10 years) were included. RVO was peripheral in 113 cases. Genetic thrombophilia was detected in 13% of patients. Acquired thrombophilia was observed in 10% of cases and 4.7 % of controls (P < 0.01). Sixty-three percent of cases and 24.6% of controls had serum hyperhomocysteinemia (odds ratio [OR] 5.2, IC 95% 2.7-10.1; P < 0.0001) : In RVO patients aged <50 years (n = 11), 36.4% had genetic thrombophilia (P = 0.04), as well as 50% of those without vascular risk factors (n = 18; P = 0.01). Forty-one (24%) patients with RVO received antiplatelet agents and 13 (7.6%) were on anticoagulants due to preexistent atrial fibrillation.

CONCLUSIONS

We suggest that, in patients with RVO, hyperhomocysteinemia and antiphospholipid syndrome should be ruled out. Moreover, a study of genetic thrombophilia should only be considered in those aged <50 years or without cardiovascular risk factors. Antiplatelet therapy with aspirin is probably the treatment of choice of RVO, to reduce the overall vascular risk. Anticoagulation should only be considered in patients with high-risk thrombophilia.

Mean platelet volume in retinal vein occlusion

OBJECTIVE

The exact pathogenic mechanism underlying the thrombotic tendency in retinal vein occlusion (RVO) is still not fully established. We investigated relationship between platelet indices including mean platelet volume (MPV) and platelet count in RVO patients compared to control group.

PATIENTS AND METHODS

Forty six patients (19 female, 27 male) diagnosed as RVO were included in the study. Forty-six subjects (26 female, 20 male) served as controls. Patients were evaluated by careful biomicroscopic examination using a fundus contact lens and fluorescein angiography. Blood samples for total blood count with MPV were obtained after overnight fasting from the antecubital vein.

RESULTS

The mean platelet volume was 8.11 ± 1.15 fl in RVO group. It was 8.68 ± 0.98 fl in controls. When compared, the mean MPV was significantly lower in RVO patients (p < 0.05). The mean platelet volume was also significantly lower in branch retinal vein occlusion group in comparison to controls (7.92 ± 1.19 fl. versus 8.68 ± 0.98 fl.) (p < 0.05).

CONCLUSIONS

MPV was significantly lower in patients with RVO than control group. MPV does not seem to be a potentially useful biomarker for prediction of RVO.

A new insight into retinal vein occlusion pathogenesis

AIM

To evaluate (ex vivo) the characteristic of fibrin clotting in patients with retinal vein occlusion.

MATERIAL AND METHODS

Fifty nine patients with a history of retinal vein occlusion were enrolled in the study. The diagnosis of retinal vein occlusion was based on the typical fundus appearance, supplemented by digital photography, fluorescein angiography, and optical coherence tomography. The control group consisted of 59 subjects matched for age, sex, body mass index, medications, and cardiovascular risk factors. The ex vivo fibrin clots obtained from citrate plasma samples from all patients were used for the measurement of clot permeation, expressed as the permeability coefficient, Ks (Darcy constant). The turbidity of fibrin clot formation, reflected by the "lag phase" of the turbidity curve and maximum absorbance at plateau (deltaAb(max)), tissue-plasminogen activator (t-PA) - induced fibrinolysis characterized by maximum rates of increase in D-dimer levels (D-Drate) and maximum D-dimer concentrations (D-Dmax) were evaluated. The time required for 50% decrease in maximum clot absorption (t50%) was chosen as an additional marker of clot susceptibility to fibrinolysis.

RESULTS

Patients with retinal vein occlusion were characterized by the unfavourable plasma fibrin clot properties. Clot permeability was 30% lower, as compared to the controls (p < 0.0001), the "lag phase" was 11% shorter (p < 0.0001) indicating faster fibrin formation, and the deltaAb(max) was 19% higher (p < 0.0001), indicating thicker fibrin fibers. The D-Dmax indicating thrombotic mass available for fibrinolytic agents was 22% higher in the RVO group (p < 0.0001) and the t50% was 29% longer (p < 0.0001) compared with controls. Only the D-Drate was similar in both groups (p = 0.223). The differences remained statistically significant after adjustment for fibrinogen, glucose, and platelet count.

CONCLUSION

The results indicate that in patients with retinal vein occlusion, less porous plasma fibrin clots composed of thicker fibrils with the reduced permeability and susceptibility to lysis are found, as compared to controls. Plasma fibrinogen and C-reactive protein levels are recognized as the most important modulators of fibrin function. retinal vein occlusion, pathogenesis.

[Thrombophilia - a risk factor of retinal vein occlusion?]

To evaluate thrombophilia as a risk factor of retinal vein occlusion in comparison with a control group and a general polish population.

MATERIAL AND METHODS

Fifty nine consecutive patients with retinal vein occlusion were enrolled in this study. The diagnosis of retinal vein occlusion was based on the presence of typical findings in the eye fundus, fluorescein angiography, and optical coherence Stomography. Control group consisted of 59 subjects matched for age, sex, body mass index (BMI), medications, and cardiovascular risk factors. In all patients the following thrombophilic factors were evaluated: factor V mutation, 20210A prothrombin mutation, MTHFR (methy-lenetetrahydrofolatereductase) mutation C677T, protein C and free protein S level, antithrombin activity, factor VIII activity, anty-beta2 glikoprotein I antibodies level, anticardiolipin antibodies level, the presence of lupus anticoagulant, total homocysteine concentration.

RESULTS

In both groups with retinal vein occlusion and control group a high incidence of factor V Leiden was observed: 10.2% and 15.6%, respectively. In one patient the presence of 20210A prothrombin mutation was noted and in one the deficiency of free S protein was observed. Antiphospholipid antibodies were present in 11.8% of cases and factor VIII concentration > 150% in 3% of patients with retinal vein occlusion. In 8.5% of patients with retinal vein occlusion genotype TT MTHFR was present. Hyper-homocysteinemia was found in 5 cases with retinal vein occlusion (8.5%) and in 7 in a control group (11.9%). In a venous blood of patients with retinal vein occlusion homocysteine level was lower by 14.5% as compared with a control group (9.4 [7.0-11.3] vs. 11.0 [9.4-12 .8] micromol/l, p = 0.001).

CONCLUSIONS

The results of thrombophilia screening in patients with retinal vein occlusion showed no statistical differences as compared with a control group matched for age, sex, and cardiovascular risk factors. However patients with retinal vein occlusion showed statistically significant lower serum homocysteine concentration as compared with a control group. Two times higher prevalence of factor V Leiden was observed in patients with retinal vein occlusion than in Polish general population.

[Evaluation of coagulopathies and fibrinolytic abnormalities in central retinal vein occlusion in patients under 60 years of age]

PURPOSE

To investigate the association of thrombophilic and fibrinolytic factors with central retinal vein occlusion (CRVO) in patients under 60 years of age.

MATERIALS AND METHODS

A prospective, observational study of 21 patients with CRVO compared with an age- and sex-matched control group of 23 volunteers was performed. All participants were tested for: cholesterol, hypertension, factors VIII, IX, and XI, homocysteine, antiphospholipid antibodies, antithrombin III, proteins C and S, protein Z and protein Z antibodies, resistance to activated protein C, factor V Leiden mutation, prothrombin mutation, MTHFR genotypes, plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (t-PA) polymorphisms.

RESULTS

There was a significantly higher rate of hyperhomocysteinemia (23.8% versus 0%, P=0.018) in CRVO patients. Increased level of factor VIII was more common in the CRVO group at diagnosis (23.8% versus 0%, P=0.018) but no significant difference was observed after one month (P=0.1). Hypercholesterolemia was more common in the CRVO group (42.8% versus 17.4%, P=0.09). Thirty-eight percent of patients with CRVO were hypertensive. Frequencies of other hypercoagulable states were rare. No significant differences were observed for hereditary fibrinolytic abnormalities.

DISCUSSION AND CONCLUSION

Among the coagulopathies studied, hyperhomocysteinemia appears to be a risk factor for central retinal vein occlusion in patients under 60 years of age. Conversely, polymorphisms of fibrinolytic factors do not appear to play a role in this population.

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.

Comprehensive analysis of inflammatory immune mediators in vitreoretinal diseases

Inflammation affects the formation and the progression of various vitreoretinal diseases. We performed a comprehensive analysis of inflammatory immune mediators in the vitreous fluids from total of 345 patients with diabetic macular edema (DME, n = 92), proliferative diabetic retinopathy (PDR, n = 147), branch retinal vein occlusion (BRVO, n = 30), central retinal vein occlusion (CRVO, n = 13) and rhegmatogenous retinal detachment (RRD, n = 63). As a control, we selected a total of 83 patients with either idiopathic macular hole (MH) or idiopathic epiretinal membrane (ERM) that were free of major pathogenic intraocular changes, such as ischemic retina and proliferative membranes. The concentrations of 20 soluble factors (nine cytokines, six chemokines, and five growth factors) were measured simultaneously by multiplex bead analysis system. Out of 20 soluble factors, three factors: interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant protein-1 (MCP-1) were significantly elevated in all groups of vitreoretinal diseases (DME, PDR, BRVO, CRVO, and RRD) compared with control group. According to the correlation analysis in the individual patient's level, these three factors that were simultaneously increased, did not show any independent upregulation in all the examined diseases. Vascular endothelial growth factor (VEGF) was significantly elevated in patients with PDR and CRVO. In PDR patients, the elevation of VEGF was significantly correlated with the three factors: IL-6, IL-8, and MCP-1, while no significant correlation was observed in CRVO patients. In conclusion, multiplex bead system enabled a comprehensive soluble factor analysis in vitreous fluid derived from variety of patients. Major three factors: IL-6, IL-8, and MCP-1 were strongly correlated with each other indicating a common pathway involved in inflammation process in vitreoretinal diseases.

Role of haemorheological factors in patients with retinal vein occlusion

Retinal vein occlusion (RVO) is an important cause of permanent visual loss. Hyperviscosity, due to alterations of blood cells and plasma components, may play a role in the pathogenesis of RVO. Aim of this case-control study was to evaluate the possible association between haemorheology and RVO. In 180 RVO patients and in 180 healthy subjects comparable for age and gender we analysed the whole haemorheological profile: [whole blood viscosity (WBV), erythrocyte deformability index (DI), plasma viscosity (PLV), and fibrinogen]. WBV and PLV were measured using a rotational viscosimeter, whereas DI was measured by a microcomputer-assisted filtrometer. WBV at 0.512 sec(-1) and 94.5 sec(-1) shear rates as well as DI, but not PLV, were found to be significantly different in patients as compared to healthy subjects. At the logistic univariate analysis, a significant association between the highest tertiles of WBV at 94.5 sec(-1) shear rate (OR: 4.91, 95% CI 2.95-8.17; p < 0.0001), WBV at 0.512 sec(-1) shear rate (OR: 2.31, 95% CI 1.42-3.77; p < 0.0001), and the lowest tertile of DI (OR: 0.18, 95% CI 0.10-0.32; p < 0.0001) and RVO was found. After adjustment for potential confounders, the highest tertiles of WBV at 0.512 sec(-1) shear rate (OR: 3.23, 95% CI 1.39-7.48; p = 0.006), WBV at 94.5 sec(-1) shear rate (OR: 6.74, 95% CI 3.06-14.86; p < 0.0001) and the lowest tertile of DI (OR: 0.20,95% CI 0.09-0.44, p < 0.0001) remained significantly associated with the disease. In conclusion, our data indicate that an alteration of haemorheological parameters may modulate the susceptibility to the RVO, by possibly helping to identify patients who may benefit from haemodilution.

High-throughput capillary electrophoresis method for plasma cysteinylglycine measurement: evidences for a clinical application

Increased levels in plasma homocysteine and cysteine, and more recently, decreased levels in cysteinylglycine have been indicated as a risk factor for vascular diseases. Most assays focused their attention only on homocysteine determination and when also other thiols were measured, analytical times drastically increased. By modifying our previous method for thiols detection, we set up a rapid capillary electrophoresis method for the selective quantification of plasma cysteinylglycine, cutting the analysis time of about 50%. Samples were treated with tri-n-butylphosphine as reducing agent, proteins were precipitated with trichloroacetic acid and released thiols were successively derivatized by the selective thiol laser-induced fluorescence-labeling agent 5-iodoacetamidofluorescein and separated by capillary electrophoresis. A baseline separation between peaks was obtained in about 2 min using 3 mmol/L sodium phosphate/2.5 mmol/L boric acid as electrolyte solution with 75 mmol/L N-methyl-D-glucamine at pH 11.25 in a 47 cm long capillary with a cartridge temperature of 45 degrees C. The method application was checked by measuring plasma Cys-Gly levels in a group of patients affected by retinal vein occlusion (RVO), an important cause of visual loss in the elderly. The low levels of Cys-Gly found in the RVO patients suggest that these small thiols may have importance in the disease development.

Hyperhomocysteinemia and central retinal vein occlusion in Iranian population

PURPOSE

To evaluate total plasma homocysteine level during the acute phase of central retinal vein occlusion (CRVO) in the Iranian population and determine whether hyperhomocysteinemia is also a risk factor for CRVO.

METHODS

Fifty-four patients with recently diagnosed CRVO were studied. Their fasting total plasma homocysteine level was compared with a matched control group of 51 patients evaluated in the same clinic for a non-retinal disease diagnosis.

RESULTS

The mean total plasma homocysteine level was 14.76+/-7.67 micromol/l in cases, and 11.42+/-3.74 micromol/l in control subjects. It showed a significant difference (P=0.005) in mean plasma homocysteine level between cases and control group. Odds ratio of CRVO for individuals with hyperhomocysteinemia was 2.88 (95% CI=1.08-7.71 and P=0.03). The overall multivariable-adjusted odds of CRVO in participants with plasma homocysteine level above 15 micromol/l was 4.71 (95% CI=1.46-15.19 and P=0.009) Hyperhomocysteinemia was not statistically different in each age group (<60 years: 27%, 61-70 years: 33.3%, 71-80 years: 31.6%, >81 years: 33.3%, Chi-square test, P=0.98).

CONCLUSION

Elevated total plasma homocysteine level is an independent risk factor for CRVO in Iranian population. In addition to an evaluation of all conventional cardiovascular risk factors, measurement of total homocysteine for evidence of hyperhomocysteinemia may be important in the initial investigation and management of patients with CRVO.

Role of inflammation in retinal vein occlusion

BACKGROUND

Inflammation measured by using highly sensitive C-reactive protein (hs-CRP) may be a separate risk factor in retinal vein occlusion (RVO).

METHODS

In a small consecutive pilot case series, hs-CRP was measured in 11 patients with RVO.

RESULTS

Levels ranged from 1.0 to 18.0 mg/L (mean 6.5 [SD 6.1] mg/L), with >3.0 mg/L being considered high risk for developing vascular disease.

INTERPRETATION

The new role of hs-CRP is important for ophthalmologists because of its part in vascular disease.

Role of hyperhomocystinemia in retinal vascular occlusive disease

Elevated plasma homocysteine (Hcy) level is considered a risk factor for vascular diseases. In recent years, many scientific reports have suggested that hyperhomocystinemia may be associated with an increased risk of retinal vascular occlusive disease (RVOD). The prevalence of elevation of homocysteine in patients with a recent retinal vascular occlusion was compared to a health control group in this study. Forty-nine consecutive patients (22 M; 27 F) (age 26-85 years, mean 69) with diagnosis of retinal vascular occlusion were compared with 71 healthy controls. These patients underwent laboratory evaluation for plasma fasting total homocysteine, activated protein C resistance, protein C, protein S, antithrombin III, and antiphospholipid and anticardiolipin antibodies. The G20210 prothrombin gene mutation (FII G20210A) and Factor V Leiden mutation (FVL) were evaluated. None of these enrolled subjects had other prothrombic risk factors. The health control group consisted of healthy subjects from the general population, with no history or clinical evidence of retinal vascular disease, recruited during the same 2-year period. High fasting homocystinemia (higher than 15 mumol/L) was detected in 24/49 subjects (48.9%) (P < .0005). There was a high prevalence of hyperhomocystinemia: these data suggest an association between RVOD and high fasting homocystinemia. Elevated homocysteine may be an independent risk factor, and its assessment may be important in the investigation, management, and follow-up of patients with RVOD. Further controlled studies are necessary to clarify the exact role of hyperhomocystinemia in RVOD and to evaluate the appropriate therapeutic approach.

Hyperhomocysteinemia and low methionine stress are risk factors for central retinal venous occlusion in an Indian population

PURPOSE

The underlying cause of disturbed homocysteine metabolism is incompletely understood in young persons with central retinal vein occlusion (CRVO) with mild hyperhomocysteinemia (HHcys) and no other systemic disease in India. A 2-year prospective study was undertaken to determine whether HHcys is a risk factor for CRVO in an Indian population.

METHOD

The prevalence of fasting HHcys was evaluated in a consecutive series of 29 patients with CRVO (mean age, 30 +/- 6 years) along with 57 age- and sex-matched control subjects (healthy subjects, mean age 27 +/- 5 years). Strict inclusion and exclusion criteria were used. Plasma levels of homocysteine (Hcys), methionine, cysteine, glutathione, B(12), and folate were measured. Multivariate logistic regression analysis was performed to determine the risk factors for CRVO.

RESULT

Fifteen of 29 patients with CRVO (51.72%) exhibited HHcys (>15 muM). The mean Hcys level was significantly elevated in the patients with CRVO (19.1 +/- 13.1 muM) compared with that in the healthy control subjects (14.7 +/- 6.2 muM) with P = 0.04. The increased Hcys levels in CRVO cases was associated with decreased methionine (P = 0.052) and decreased B(12) (P = 0.001). A multivariate logistic regression analysis revealed an odds ratio of 1.9 (95% CI = 0.50-7.16) for Hcys and 15.9 for methionine (95%CI = 1.50-169.62; P = 0.022).

CONCLUSION

Elevated Hcys and low methionine were risk factors for CRVO in an Indian population.

Low density lipoprotein triglycerides and lipoprotein(a) are risk factors for retinal vascular occlusion

BACKGROUND

Retinal artery occlusion (RAO) and retinal vein occlusion (RVO) are common causes of severe visual loss and several atherothrombotic risk factors such as hyperlipidemia, diabetes mellitus and arterial hypertension have been associated with these ophthalmic lesions.

METHODS

In this retrospective study we investigated 66 patients with RAO, 87 patients with RVO and 405 age- and gender-matched control subjects. Lipoproteins were separated using an ultracentrifugation-precipitation method (beta-quantification) and the levels of lipids and apolipoproteins in VLDL, LDL and HDL particles were measured.

RESULTS

After adjusting for the type of occlusion and lipid-lowering medication, patients with RVO and RAO versus controls had significantly higher levels of LDL-cholesterol (3.82+/-1.06, 3.59+/-0.90 and 3.07+/-0.83 mmol/L), LDL-triglycerides (0.39+/-0.14, 0.40+/-0.12 and 0.35+/-0.14 mmol/L) and apolipoprotein B (1.06+/-0.27, 1.05+/-0.26 and 0.84+/-0.21 g/L) in the LDL fraction, respectively. In RAO, LDL-triglycerides were independently associated with retinal vascular occlusion. Interestingly, apolipoprotein AI was elevated in both patient groups compared to controls. The most striking differences were found in lipoprotein(a) where both RVO and RAO patients had significantly higher levels than the control subjects (median values: 320, 290 and 130 mg/L, respectively).

CONCLUSION

These findings suggest that disorders in lipoprotein metabolism may contribute to the etiology of retinal vascular occlusions.

Platelet activation by collagen is increased in retinal vein occlusion

Retinal vein occlusion (RVO) is the most common retinal vascular disorder second to diabetic retinopathy. The main risk factors in patients with RVO are hypertension, diabetes, hyperlipidemia, increased blood viscosity and glaucoma. The pathogenesis of RVO has not yet been clarified. In these events platelets could play a very important role. In the present study the platelet response to collagen was deeply investigated. Experiments were carried out on a selected group of RVO patients, which were compared to a group of healthy subjects matched for age, sex, clinical and metabolic characteristics. In resting and activated platelets of both groups of subjects p72syk phosphorylation, phospholipase Cgamma2 phosphorylation, protein kinase C activation, intra-cellular calcium levels and nitric oxide formation were measured. Results show that platelets of patients were more responsive to collagen or ADP than healthy subjects and that the response was significantly different (p < 0.0005) at low concentrations of these agonists. In platelets of patients stimulated with collagen increased phosphorylation of p72syk and phospholipase Cgamma2 was found. Also protein kinase C was more activated in patients. In addition intracellular calcium rise induced by collagen was significantly higher in patients than in healthy subjects. RVO patients showed a lower basal level of nitric oxide both in resting and stimulated platelets compared to healthy subjects. Altogether these results suggest that the platelet hyperaggregability described in patients might be an important factor in the development of RVO contributing to the thrombogenic effects.

The deficiencies of protein C, protein S and antithrombin III in patients with retinal vein occlusion: a Turkish sample

The aim of this study was to test the role of the decreased levels of protein C (PC), protein S and antithrombin III on the pathogenesis of retinal vein occlusion (RVO). Of 54 patients with RVO, seven had the decreased levels of PC. We found statistically significant differences for the rate of cases with PC deficiency between the patients with RVO and controls (P < 0.05).

Plasma methionine determination by capillary electrophoresis-UV assay: application on patients affected by retinal venous occlusive disease

Methionine is an important amino acid involved in protein synthesis and transmethylation reactions. It is also the precursor of homocysteine and cysteine, two important risk factors for cardiovascular diseases. As homocysteine research has gained impulsion, the evaluation of plasma methionine concentrations has acquired importance. Methionine measurement generally has been performed by HPLC after o-phthalaldehyde derivatization. Its separation from other amino acids is time-consuming. We set up a new specific capillary electrophoresis method in which analyte derivatization was avoided by sample concentration before analysis. Methionine was detected by UV absorbance at 204 nm with a detection limit of 0.5 micromol/L. By a capillary with an effective length of 50 cm filled with 125 mmol/L Tris phosphate buffer at pH 2.3, the separation occurred in less than 14 min. Precision tests indicated a good test repeatability for both migration times (coefficient of variation [CV]<0.3%) and areas (CV<2.0%). Moreover, a good reproducibility of intraassay and interassay tests was obtained (CV<2.9% and CV<3.5%, respectively). The Passing-Bablok regression and the Bland-Altman test for methods comparison suggest that the data obtained by our method and by a reference HPLC assay are similar. Assay performance was evaluated measuring methionine concentrations in retinal venous occlusive disease.

Clinical haemorheology and microcirculation

Hyperviscosity, due to alterations of blood cells and plasma components, can induce microvascular damage. Nitric oxide (NO) is released by endothelium and plays a crucial role in flow-mediated vasodilation. An impaired availability of NO, due to polymorphisms of endothelial NO synthase (eNOS), may influence erythrocyte deformability thus increasing blood viscosity. We investigated haemorheological variables in patients with idiopathic sudden sensorineural hearing loss (ISSHL), retinal vein occlusion (RVO) and systemic sclerosis (SSc), as possible models of microvascular damage, and their relationship with eNOS gene T-786C, G894T and 4a/4b polymorphisms. Whole blood viscosity and plasma viscosity were assessed with a rotational viscosimeter and erythrocyte deformability index (DI) with Myrenne filtrometer. eNOS polymorphisms were analyzed in ISSHL and SSc patients. At multivariate analysis alterations of some haemorheological variables resulted significantly associated with ISSHL, RVO and SSc. A significantly higher prevalence of eNOS -786C and 894T was found in both ISSHL and SSc patients than in controls; at multivariate analysis these two polymorphisms significantly affected DI in both groups of patients. These results suggest that hyperviscosity, either determined by genetic susceptibility or not, can be involved in the pathophysiology of these clinical disorders and can be the target of new therapeutic strategies.

Plasma Homocysteine and Cysteine Levels in Retinal Vein Occlusion

PURPOSE

To determine plasma homocysteine and cysteine levels in patients with retinal vein occlusion (RVO) and in healthy subjects and to ascertain whether there are statistically significant differences between patients and control subjects.

METHODS

In this case-control study, the study group consisted of 75 consecutive patients with RVO: 33 had central retinal vein occlusion (CRVO), and 42 had branch retinal vein occlusion (BRVO). Seventy-two apparently healthy age- and sex-matched subjects served as control subjects. Homocysteine and cysteine levels were measured with a new laser-induced fluorescence capillary electrophoresis (CE-LIF) METHOD: Wilcoxon or Student's t-test was used, when appropriate, to determine differences between groups.

RESULTS

There were no significant differences in median plasma homocysteine between patients with RVO and control subjects, nor were there any statistically significant differences when patients were categorized by type of vein occlusion (CRVO or BRVO). Similarly, there were no significant differences in mean plasma cysteine between patients with RVO and control subjects. However, when categorized by type of vein occlusion, mean plasma cysteine was significantly higher in CRVO patients than in control subjects (P = 0.034).

CONCLUSIONS

This study failed to demonstrate an association between increased plasma homocysteine and RVO. Mean plasma cysteine was significantly higher in patients with CRVO, suggesting that hypercysteinemia may contribute to the pathogenesis of this retinal vascular disorder.

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.

Plasma homocysteine levels and vitamin B status in patients with Pseudoexfoliation syndrome

OBJECTIVE

To determine and compare the plasma levels of homocysteine and vitamin B (B6, B12 and folate) in patients with Pseudoexfoliation syndrome (PEXS), pseudoexfoliation glaucoma (PEXG), retinal vein occlusion with pseudoexfoliation (PEX+RVO) and in normal individuals.

METHODS

The current study was conducted in the Third Eye Clinic, Ankara Numune Training and Research Hospital, Turkey, between August 2004 and February 2005. Twenty cases with PEXS (Group 1), 20 cases with PEXG (Group 2), 16 cases with PEX+RVO (central or branch retinal vein occlusion) (Group 3) and 20 normal individuals (control group) were included in the study. Those who use vitamin supplements or drugs affecting the plasma homocysteine levels were excluded from the study.

RESULTS

Plasma homocysteine levels were 17.6+/-4.4 mmol/l in Group 1, 18.5+/-4.5 mmol/l in Group 2, 22.2+/-6.0 mmol/l in Group 3, and 14.0+/-3.1 mmol/l in the control group. It was highest in Group 3 (p<0.001). The ratio of hyperhomocysteinemia was calculated as 35% (Group 1), 45% (Group 2), 68.7% (Groups 3) and 15% (control). These values were statistically higher in the groups with PEXS than in the control group (p=0.009). We did not find any statistically significant difference between the groups with respect to the levels of vitamin B6 and B12 (p>0.05), but the level of folate was lowest in Group 3 (p<0.001).

CONCLUSION

Hyperhomocysteinemia is a risk factor for thromboembolic vasculopathy in patients with PEXS and PEXG. Therefore, vitamin B supplementation should be considered in these patients when hyperhomocysteinemia is detected.

Hyperhomocysteinemia and low plasma folate as risk factors for central retinal vein occlusion: a case-control study in a Chinese population

PURPOSE

To determine whether hyperhomocysteinemia and low plasma folate are risk factors for central retinal vein occlusion (CRVO) in the Chinese population.

METHODS

A matched case-control study was conducted between July 2004 and May 2005. The study cohort consisted of 64 individuals that had been diagnosed to have CRVO and 64 normal controls (matched for age, gender, hypertension, smoking and drinking habits). None of the cases or controls had a history of diabetes, glaucoma, medication or any other vascular events that might minimize the influence on plasma homocysteine levels. A cross-sectional analysis among the 64 cases was performed to compare the prevalence of hyperhomocysteinemia and low plasma folate among subjects with and without ischemia and subjects with age above 45 and below 45 years. Plasma homocysteine level was measured by means of high-performance liquid chromatography and plasma folate concentration by radioimmunoassay.

RESULTS

The CRVO patients had a significantly higher homocysteine level (13.83+/-1.71 micromol/l) than the normal controls (8.05+/-0.58 micromol/l; p=0.003). The plasma folate levels were significantly lower in CRVO patients than in controls (5.62+/-0.39 ng/dl vs 7.23+/-0.60 ng/dl; p=0.032). A 1 micromol/l increase of plasma homocysteine level was associated with an odds ratio of 1.368. Hyperhomocysteinemia was defined as a homocysteine level of >14.97 micromol/l and was seen in 11 patients in the ischemic group, significantly more often than in the non-ischemic group (5 patients; p=0.030).

CONCLUSIONS

The results suggest that hyperhomocysteinemia and low plasma folate are independent risk factors for CRVO and are associated with the development of CRVO in the Chinese population.

Retinal vein occlusion, homocysteine, and methylene tetrahydrofolate reductase genotype

PURPOSE

The aim of this case-control study was to investigate the relationship between homocysteine (tHcy), 5,10 methylene tetrahydrofolate reductase (MTHFR) C677T genotype, folate and vitamin B12 status, and retinal vein occlusion (RVO).

METHODS

Subjects with RVO (n = 106) were recruited from outpatient and inpatient sources. Controls (n = 98) were selected to achieve a similar age and sex distribution. Full ocular examination was performed and medical history was taken for each study participant. Plasma and serum samples were analyzed for tHcy level and folate and vitamin B12 status, and extracted DNA was assessed for the MTHFR C677T genotype.

RESULTS

There was no significant difference in plasma tHcy level or thermolabile MTHFR allele frequency between subjects and controls. Similarly, there was no significant difference in folate or vitamin B12 status between subjects and controls. MTHFR genotype did not affect folate or vitamin B12 concentrations in subjects or controls. However, tHcy was significantly higher in thermolabile homozygotes than in nonthermolabile homozygotes (ratio of geometric means, 1.35; 95% confidence interval [CI], 1.04-1.74; P = 0.024).

CONCLUSIONS

Hyperhomocysteinemia, the MTHFR C677T mutation, and folate and vitamin B12 status are not important risk factors for RVO in this population.

MODERATE HYPERHOMOCYSTEINEMIA AND EARLY-ONSET CENTRAL RETINAL VEIN OCCLUSION

PURPOSE

To evaluate the prevalence of moderate fasting hyperhomocysteinemia (HHcy) and postmethionine load (PML) HHcy among patients with early-onset central retinal vein occlusion (CRVO).

METHODS

The prevalence of fasting HHcy and that of PML HHcy were evaluated in a consecutive series of 58 patients with CRVO who were younger than 56 years of age (mean age, 40.3 years) and in 103 controls (mean age, 39.6 years). Plasma folate, vitamin B12, and pyridoxal-5'-phosphate (PLP) levels were measured in 42 patients and 67 controls.

RESULTS

Mantel-Haenszel odds ratios for CRVO patients were 3.00 (95% confidence interval [CI], 0.83-10.8) for fasting HHcy, 3.50 (95% CI, 1.07-11.4) for PML HHcy, and 3.00 (1.18-7.6) for fasting HHcy and PML HHcy in subjects with normal fasting total homocysteine (tHcy) levels. Moderate HHcy was associated with reduced plasma levels of folate and PLP (P < or = 0.04). There was no significant dependence of fasting and PML tHcy levels on any traditional risk factor evaluated.

CONCLUSIONS

Moderate HHcy is an independent risk factor for early-onset CRVO.

Protein Z levels and central retinal vein or artery occlusion

OBJECTIVES

Central retinal vein occlusion (CRVO) and central retinal artery occlusion (CRAO) are common disorders associated with risk factors for atherosclerosis. Protein Z is a cofactor for the inactivation of activated factor X (Xa) by the protein Z dependent protease inhibitor. Protein Z deficiency was recently linked to increased risk of arterial thrombosis. We investigated whether CRVO and CRAO are associated with low protein Z levels.

PATIENTS AND METHODS

Patients with CRVO, CRAO or recurrent branch retinal vein occlusion were recruited to the study. Protein Z level, lupus anticoagulant (LAC), anticardiolipin antibodies (ACA) and activated protein C resistance (APCR) were determined in plasma from patients (n = 36) and healthy controls (n = 42).

RESULTS

Thirty patients in the study group had traditional risk factors for retinal vessel occlusion and six patients had none. There was no significant difference in protein Z levels between the whole study group patients and controls (1995 +/- 810 vs. 2010 +/- 603 ng/mL, P = 0.922). However, patients with no risk factors for retinal vessel occlusion had significantly lower protein Z levels than controls (1379 +/- 682 vs. 2010 +/- 603 ng/mL, P = 0.022). Positive LAC was found in six patients and one control subject (P = 0.04). There were three patients and one control subject with abnormal APCR (P = 0.3) and none with positive ACA. Low protein Z level (lower than fifth percentile of control) was not associated with the presence of LAC or APCR.

CONCLUSION

Low protein Z level may be another risk factor for retinal vessel occlusion in patients without traditional risk factors for these disorders.

Anticardiolipin IgG antibody and homocysteine as possible risk factors for retinal vascular occlusive disease in thai patients

PURPOSE

To assess the role of serum anticardiolipin IgG antibody and fasting plasma homocysteine levels as risk factors for retinal vascular occlusive disease in Thai patients.

METHODS

This is a retrospective, case-control study. Forty-one consecutive patients with recent onset of retinal vascular occlusive diseases were enrolled. In conjunction with a routine laboratory work up, serum anticardiolipin IgG antibody and plasma homocysteine were evaluated. Ninety volunteers without a history of retinal vascular occlusive disease were chosen as controls.

RESULTS

In general, mean levels of anticardiolipin IgG antibody and homocysteine did not differ between the patients and controls. However, when the groups without a history of underlying systemic diseases were compared, there were statistically significant differences in the anticardiolipin IgG antibody level between patients and controls (mean 12.24 +/- 8.66 and 7.70 +/- 6.69 GPL units/ml, respectively) with a P value of 0.024.

CONCLUSIONS

No association was found between plasma homocysteine level and retinal vascular occlusion in our patient population. A high level of anticardiolipin IgG antibody is shown to be a risk factor only in patients without a history of underlying systemic diseases. The effect of anticardiolipin IgG antibody on the development of retinal vascular occlusive disease appears to be limited and may not be a major cause.

Determinación de factores trombofílicos en pacientes con trombosis venosas retinianas

BACKGROUND

Thrombophilia is an alteration of hemostasis that increases the risk to venous or arterial thrombosis. This condition may be the underlying cause of retinal vein thrombosis.

AIM

To study the presence of thrombophilia in patients with retinal vein thrombosis.

PATIENTS AND METHODS

Prospective study of 55 patients aged 22 to 86 years, with retinal vein thrombosis (central or branch). Antithrombin III, coagulant protein C, functional protein S, resistance to activated C protein, homocysteine, prothrombin G20210A gene, lupus anticoagulant and anticardiolipin antibodies were measured in all.

RESULTS

Seventeen patients had thrombophilic markers (antiphospholipid syndrome in seven, hyperhomocysteinemia in six and resistance to protein C in three). Of these 17 patients, 53% had high blood pressure, 35% an abnormal serum lipid profile and 23% a personal history of thrombosis. The thrombosis was central in 12 (ischemic in four) and of a branch in five (ischemic in two).

CONCLUSIONS

Thrombophilic markers must be assessed in patients with retinal vein thrombosis.

[Factor VIII activity in patients with central retinal vein occlusion in comparison to patients with a history of pelvic and lower limb venous thrombosis and a healthy control group]

BACKGROUND

High factor VIII activity levels increase the risk of venous thromboembolism. This study was carried out to investigate the association between factor VIII activity and central retinal vein occlusion (CRVO) in comparison to patients with a history of venous thrombosis and a healthy control group.

PATIENTS AND METHODS

We examined the factor VIII activity in 62 patients with CRVO, 67 patients with venous thrombosis and 107 healthy individuals. The study measure employed for factor VIII activity was a one-stage clotting assay.

RESULTS

53.2 % of the patients with CRVO had an elevated factor VIII activity of more than 150 % (> 150 IU/dl). 78.5 % of the patients with venous thrombosis and 19.7 % of the healthy control group had an elevated factor VIII activity (> 150 IU/dl).

CONCLUSIONS

Elevated factor VIII activity is likely to have an influence on the pathogenesis of the central retinal vein occlusion.

Homocysteine and retinal vein occlusion: a population-based study

PURPOSE

To report population data on the association between homocysteinemia and retinal vein occlusion (RVO).

DESIGN

Cross-sectional, population-based study.

METHODS

Total serum homocysteine (tHcy) was estimated in subjects attending the second Blue Mountains Eye Study (BMES) (n = 3509, aged >49 years). Its association with RVO (graded from retinal photographs) was examined.

RESULTS

Homocysteine was more strongly associated with RVO in younger than older participants. In those aged <70 years, homocysteine levels >15 micromol/l were associated with increased odds of RVO, odds ratio (OR) 3.76; 95% confidence interval (CI) 1.06-13.40, in multivariable-adjusted analyses. Each 1 micromol/l increase in homocysteine was associated with a 7% increased odds of RVO, OR 1.07; CI 0.99-1.17 (P = .08).

CONCLUSION

This population-based study showed that elevated serum homocysteine is associated with the presence of RVO, independent of other risk factors.

[Adequacy of prescribing the disaggregants in vascular pathology of the eye fundus and in primary open-angle glaucoma]

The functional activity of blood platelets was studied in 936 patients with vascular pathology of the eye fundus (central chorioretinal dystrophy--CCRD; preproliferative diabetic retinopathy--PPDR; proliferative diabetic retinopathy--PDR; hypertensive retinopathy--HP; thrombosis of retinal veins--TRV; and primary open angle glaucoma--POAG) by using 2 methods: the routine one, which does not expose the real process of platelets' aggregation in the blood bed, and a method, which is closer to the conditions in vivo. The non-physiological ("tube"-based) methods of determination of platelets' aggregation overstate almost 3-fold the share (%) of patients needing disaggregants. The disaggregation therapy is indicated in 28% of cases; it is more often prescribed for patients with TRV (52.2%), HP (40%), PPDR (35.5%), POAG (29%), PDR (21.5%) and CCRD (15.3%). An acute decrease of the aggregation ability of platelets was registered in 22.5% of the examinees: drugs intensifying the functional activity of platelets were used. The conclusion is that iatrogenic hemorrhages can be reduced by using adequate methods for the determination of the functional activity of platelets and by prescribing an adequate medicamental therapy.

[The content of D-dimer in peripheral blood as observed studied in thrombohemorrhagic lesions of the retina]

The content of D-dimer in peripheral blood was studied in thrombohemorrhagic lesions of the retina. 60 patients with retinal pathology of the retina, i.e. thrombosis of retinal veins, exudative-hemorrhagic stage of central chorioretinal dystrophy and preproliferative diaichbetic retinopathy with pronounced exudative hemorrhagic maculopathy, were examined. A higher concentration of D-dimer in peripheral blood was shown to be indicative of affected general hemostasis. The below main parameters, which matter in progression of thrombohemorrhagic conditions should be determined, apart from D-dimer, for choosing an adequate medicamental therapy: aggregation ability of platelets, activated partial thromboplastin time, antithrombin-III, protein-C, prothrombin time, soluble complexes of fibrinmonomer, thrombin time, plasma fibrinogen and fibrinolytic plasma activity.