Hyperhomocysteinemia in retinal artery and retinal vein occlusion

Visual functions, ocular characteristics and visual quality of life in patients with homocystinuria

BACKGROUND

Homocystinuria (HCU) is a rare metabolic disease that affects many organs, including the eyes. Aims: to assess visual functions, ocular characteristics, visual quality of life and time from the onset of ocular manifestations to HCU-diagnosis in patients with HCU.

MATERIAL AND METHODS

Eighteen patients underwent ophthalmological examinations and visual quality of life questionnaires.

RESULTS

Best corrected decimal visual acuity was median 1.0 (range amaurosis - 1.3) right eye and 1.0 (range amaurosis -1.3) left eye. Five patients presented with severe myopia as first HCU manifestation, duration to HCU diagnosis was mean 13.6 years (range 2-25). Two patients had suffered ectopia lentis as first HCU manifestation, HCU diagnosis was established mean 8.0 years (range 7-9) later. One patient had suffered both from thrombosis and ectopia lentis prior to diagnosis. Another four patients suffered thromboembolic events before diagnosis. Median VFQ-25 composite score was 93 (68-98).

CONCLUSIONS

The prevalence of myopia, ectopia lentis and monocular blindness was high in HCU-patients, which was reflected in their visual quality of life. Diagnosis was often delayed after the first ocular manifestation, increasing the risk of other severe non-ocular complications.

Prevention and Treatment of Retinal Vein Occlusion: The Role of Diet-A Review

Retinal vein occlusion (RVO) is the second most common retinal disorder. In comparison to diabetic retinopathy or age-related macular degeneration, RVO is usually an unexpected event that carries a greater psychological impact. There is strong evidence to suggest that cardiovascular diseases are the most common risk factors in this pathology and it has long been known that a higher consumption of fish, nuts, fruits, and vegetables has a protective effect against these types of conditions. In the last several years, interest in plant-based diets has grown in both the general population and in the scientific community, to the point to which it has become one of the main dietary patterns adopted in Western countries. The aim of this review is to investigate the potential impact of macro- and micronutrients on retinal vein occlusion.

Hyperbaric Oxygen Therapy for Central Retinal Artery Occlusion: Patient Selection and Perspectives

The central retinal artery occlusion (CRAO) is a rare ophthalmological emergency that can occur in the eye. CRAO can affect persons of any age, however it is most common in people over the age of 60. CRAO is associated with a number of risk factors, including giant cell arteritis, carotid artery atherosclerosis, cardiogenic emboli, hypertension, smoking, diabetes, and thromboembolic disease. The chance of each of these etiologies being present is assessed during the course of the investigation. Hyperbaric oxygen treatment (HBOT) is classified by the American Heart Association for CRAO at level IIb. In accordance with that, HBOT might be considered for the treatment of such a severe condition. HBOT can maintain retinal oxygenation during ischemic events by allowing oxygen to diffuse through choroidal capillaries that have been exposed to elevated partial pressures of oxygen. As a result, ischemia-related damage is reversed if applied within proper time frame. The amount of time that has passed prior to initiation of HBOT is considered to be the most critical factor in determining the best visual prognosis. According to the Undersea and Hyperbaric Medical Society, patients who are identified with CRAO after the onset of symptoms should be evaluated for HBOT within 24 hours. HBOT has the advantage of having a low risk profile, and it can be utilized to improve visual outcomes in proper patients.

Thrombophilic risk factors for retinal vein occlusion

The aim is to study risk factors for retinal vein occlusion (RVO), such as thrombophilic and cardiovascular risk factors (CRF). A retrospective consecutive case series of 60 patients with RVO was made, tested for CRF, hyperhomocysteinemia, lupic anticoagulant, antiphospholipid antibody and 5 gene variants: factor V (FV) Leiden (G1691A), factor II (PT G20210A), 5,1-methylenetetra-hydrofolate reductase (MTHFR; 677 C > T and 1298 A > C), plasminogen activator inhibitor 1 (PAI-1; 4 G/5 G). More than 1 CRF were present in 36 patients (60%), which had a significantly higher mean age at diagnosis (66.7 ± 12.9 versus 59.5 ± 13.7 with ≤1 CRF, [t(57) = −2.05, p = 0.045, d = 0.54). Patients with thermolabile MTHFR forms with decreased enzyme activity (T677T or C677T/A1298C) had a significant lower mean age [57.6 ± 15.1; t (58) = 3.32; p = 0.002; d = 0.846] than patients with normal MTHFR enzyme activity (68.5 ± 10.2). Regarding CRF and thermolabile forms of MTHFR, the mean age at diagnosis could be significantly predicted [F(2,56) = 7.18; p = 0.002] by the equation: 64.8 − 10.3 × (thermolabile MTHFR) − 5.31 × ( ≤ 1CRF). Screening of MTHFR polymorphisms may be useful in younger RVO patients, particularly when multiple CRF are absent.

Retinal Artery Occlusion in Young Patients: A 6-Year Review

Purpose:

This article describes the characteristics, management, and etiology of retinal artery occlusions (RAOs) in young patients.

Methods:

A retrospective chart review of patients <50 years of age with ophthalmic and RAOs was conducted. Data were collected on demographics, clinical presentation, laboratory and imaging evaluation, management, and outcome.

Results:

Seventeen eyes of 15 patients younger than 50 (mean age, 34±8 years; 71% male, 29% female) with RAOs were identified. AOs included: 8 (47%) central RAOs (CRAOs), 5 (29%) branch RAOs (BRAOs), 3 (18%) ophthalmic AOs (OAOs), and 1 (6%) combined CRAO and vein occlusion (CRAO/CRVO). Logarithm of the minimum angle of resolution visual acuity (VA) at presentation was 2.6±4 (Snellen range 20/15 to no light perception). Systemic diseases in patients with BRAO included Susac disease (n = 1), sickle cell disease (n = 2), patent foramen ovale (PFO) (n = 1), and HIV (n = 1). CRAO was diagnosed in 4 patients after invasive surgery (3 after neurosurgery and 1 after cardiac surgery). Other patients had hypertension (n = 3), hypercoagulability due to uterine cancer (n = 1), and PFO (n = 1). OAOs were noted in 1 patient with Saturday night retinopathy and in 1 with ruptured internal carotid aneurysm at the level of the ophthalmic artery. Two eyes with CRAO were treated with tissue plasminogen activator (1 intraophthalmic artery through catheterization and 1 intravenously) without any change in final VA. In these patients, VA remained poor (VA hand motions – counting fingers) at 6 months or greater follow-up visits.

Conclusion:

RAO in young patients is uncommon. In this series, one-fourth of occlusions were seen during the perioperative period. A significant number of patients had concurrent uncontrolled hypertension. Other associated systemic findings included PFO, hypercoagulability, sickle cell disease, Susac disease, and HIV.

Acute retinal vein occlusion and cystic fibrosis

Background

The ocular manifestations of cystic fibrosis typically present with surface irritation or nyctalopia due to Vitamin A deficiency, however, there have been two previous reports of patients with cystic fibrosis that developed retinal vein occlusions. These reports hypothesized that either elevated fibrinogen levels due to chronic infections or elevated homocysteine levels have predisposed patients with cystic fibrosis to develop retinal vein occlusions.

Case presentation

We present a case of a 35-year-old male with cystic fibrosis complicated by chronic sinusitis with no history of organ transplantation or chronic pulmonary infections who presented with an acute branch retinal vein occlusion in his left eye with associated macular edema. Evaluation revealed an elevated fibrinogen level, while the rest of his workup was relatively unremarkable including a normal homocysteine level. His vision remained 20/20 throughout his care and he did not require treatment of his macular edema.

Conclusions

Patients with cystic fibrosis are at an increased risk of developing retinal vein occlusions likely due to a variety of systemic thrombogenic factors rather than a single risk factor which had been reported previously. Elevated fibrinogen levels in these patients may not be due to chronic infections, but inherent to the cystic fibrosis.

Associations of Thrombophilia, Hypofibrinolysis, and Retinal Vein Occlusion

We prospectively assessed whether thrombophilia and hypofibrinolysis, amplified by thrombophilic hormone replacement therapy (HRT), were associated with retinal vein occlusion (RVO). We studied 44 cases (18 men, 26 women), ≥ 3 months after RVO, 42 with central RVO, 2 with branch RVO, in the consecutive order of their referral by 2 community-based ophthalmologists. PCR and serologic coagulation assays were compared to 83 and 40 healthy adult normal controls, respectively. The 4G allele frequency of the plasminogen activator inhibitor-1 (PAI-1) gene, associated with hypofibrinolysis, was 56 of 88 (64%) in cases vs 79 of 166 (48%) in controls, X2 = 5.95, p = .015. The PAI-1 gene product, plasminogen activator inhibitor activity (PAI-Fx), was higher in cases than controls (age-race-sex-adjusted mean 12.2 U/mL vs 6.3, p = .013). By stepwise logistic regression, the PAI-1 gene 4G allele was associated with RVO, odds ratio 1.94, 95% CI 1.12-3.34, p = .018. Thrombophilic resistance to activated protein C (RAPC) was present in 6 of 32 (19%) of cases vs 0 of 40 (0%) controls, Fisher’s p [pf] = .006. Thrombophilic high factor VIII (>150%) was present in 3 of 30 (10%) cases vs 0 of 40 (0%) controls, p = .041, pf = .07. Comparing 23 RVO cases ≤ age 55 and controls ≤ age 55 (n = 44 for PCR, n = 40 for serologic measures), RAPC was present in 17% of cases vs 0% controls (pf = .026), high Factor VIII in 17% vs 0% (pf = .026), heterozygosity for the G1691A Factor V Leiden mutation in 13% vs 2% (pf = 0.11), and the 4G allele frequency of the PAI-1 gene 74% vs 39% (p = .0001). PAIFx was higher in cases than controls (age-race-sex adjusted mean 12.7 U/mL vs 6.7, p = .016). The case-control odds ratio for the PAI-1 4G allele was 5.54, 95% CI = 1.86-16.7, p = .002. Of the 26 women, 9 (35%) took HRT; 4 of the 9 had PAI-1 gene 4G4G homozygosity, 2 had thrombophilic high anticardiolipin antibody (IgG), 1 was heterozygous for the G1691A Factor V Leiden mutation, and 2 were heterozygous for the thrombophilic PL A1/A2 mutation of the platelet glycoprotein IIb/IIIa gene. Associations between heritable coagulation disorders and RVO, most marked in cases ≤ age 55, and often amplified in women by thrombophilic HRT, are, speculatively, causal.

Hyperbaric oxygen therapy in branch retinal artery occlusion in a 15-year-old boy with methylenetetrahydrofolate reductase mutation

Purpose. To report the efficacy of hyperbaric oxygen (HBO) therapy in a case of branch retinal artery occlusion (BRAO) in a 15-year-old boy. Methods. We report a 15-year-old boy with sudden loss of vision due to BRAO. Examination included laboratory evaluation for systemic risk factors. Follow-up exams included visual acuity, fundus examination, fundus fluorescein angiography, and visual field testing. HBO therapy was employed for treatment. Results. Medical history was positive for isolated glucocorticoid deficiency. Laboratory evaluation disclosed hyperhomocysteinemia and methylenetetrahydrofolate reductase (MTHFR) mutation. The visual acuity 0.05 at presentation improved to 0.8 after 20 days of HBO therapy. There was no change on visual fields. Conclusion. In this pediatric case, HBO therapy was useful in the treatment of BRAO.

Sequential bilateral central retinal vein occlusions in a cystic fibrosis patient with hyperhomocysteinemia and hypergamma-globulinemia

PURPOSE

To report a case of sequential bilateral central retinal vein occlusions in a cystic fibrosis patient with hyperhomocysteinemia and hypergamma-globulinemia over 6 years of follow up.

METHODS

Observational case report of one patient.

RESULTS

A 31 year-old male with a history of cystic fibrosis presented with a central retinal vein occlusion (CRVO) in his left eye, followed by a CRVO in his right eye 4 years later. His medical workup was significant for elevated levels of homocysteine and gamma-globulins, which coincided with initiation of intravenous immunoglobulin (IVIG) proceeding his second CRVO.

CONCLUSIONS

We describe a case of sequential bilateral central retinal vein occlusions in a cystic fibrosis patient with hyperhomocysteinemia and hypergamma-globulinemia over 6 years of follow up and discuss the important role of these risk factors in retinal venous occlusive disease.

Reference interval determination of total plasma homocysteine in an Indian population

Hyperhomocysteinemia has been shown to be an independent risk factor for cardiovascular disease as well as retinal vascular occlusion. Because of the epidemiological, dietary, genetic and environmental diversity among the different countries, each country should establish the reference interval of homocysteine of their own population for recommending appropriate medical decision limits. Hence a total of 1,288 apparently healthy subjects including 636 male and 652 female were enrolled in the present study to determine the reference intervals of homocysteine in an Indian population. Results of the study were presented as mean, standard deviation, median and 2.5th and 97.5th percentile with the 0.90 confidence interval of each percentile values of homocysteine along with decade-wise changes.

[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.

Hyperhomocysteinemia, as an independent risk factor for retinal venous occlusion in an Indian population

Total plasma homocysteine was analysed in 64 cases of retinal vein occlusion (RVO) of which 24 cases of central retinal vein occlusion (CRVO) and 40 cases of branch retinal vein occlusion (BRVO) and compared with 45 age and sex matched control. Homocysteine was significantly increased in RVO cases in respect to control (P < 0.001). Analysis also revealed that prevalence of rise of plasma homocysteine was more in cases of CRVO (OR = 13) than that of BRVO (OR = 5.03).

Thrombophilic screening in retinal artery occlusion patients

Background

Retinal artery occlusion (RAO) is an ischemic vascular damage of the retina, which frequently leads to sudden, mostly irreversible loss of vision. In this study, blood thrombophilic factors as well as cardiovascular risk factors were investigated for their relevance to this pathology. Thrombophilic risk factors so far not evaluated were included in the study.

Patients and methods

28 RAO patients and 81 matched control subjects were examined. From blood samples, protein C, protein S, antithrombinopathy, and factor V (Leiden) mutation (FV), factor II gene polymorphism, factor VIIIC level, plasminogen activity, lipoprotein(a) and fibrinogen levels, hyperhomocysteinemia and presence of anticardiolipin – antiphospholipid antibodies were investigated. Possibly relevant pathologies such as diabetes mellitus, hypertension, and ischemic heart disease were also registered. Statistical analysis by logistic regression was performed with 95% confidence intervals.

Results

In the group of patients with RAO only the incidence of hypertension (OR: 3.33, 95% CI: 1.30–9.70, p = 0.014) as an average risk factor showed significant difference, but thrombophilic factors such as hyperfibrinogenemia (OR: 2.9, 95% CI: 1.29–6.57, p = 0.010) and the presence of FV (Leiden mutation) (OR: 3.9, 95% CI: 1.43–10.96, p = 0.008) increased the chances of developing this disease.

Conclusions

Our results support the assumption that thrombophilia may contribute to the development of RAO besides vascular damage due to the presence of cardiovascular risk factors. Further studies are needed, however, to justify the possible use of secondary prophylaxis in form of anticoagulant/antiplatelet therapy.

Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism, and risk of retinal vein occlusion: a meta-analysis

OBJECTIVE

To assess the role of plasma total homocysteine (tHcy) concentrations and homozygosity for the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) C677T gene as risk factors for retinal vascular occlusive disease.

DESIGN

Retinal vein occlusion (RVO) is an important cause of vision loss. Early meta-analyses showed that tHcy was associated with an increased risk of RVO, but a significant number of new studies have been published.

PARTICIPANTS AND/OR CONTROLS

RVO patients and controls.

METHODS

Data sources included MEDLINE, Web of Science, and PubMed searches and searching reference lists of relevant articles and reviews. Reviewers searched the databases, selected the studies, and then extracted data. Results were pooled quantitatively using meta-analytic methods.

MAIN OUTCOME MEASURES

tHcy concentrations and MTHFR genotype.

RESULTS

There were 25 case-control studies for tHcy (1533 cases and 1708 controls) and 18 case-control studies for MTHFR (1082 cases and 4706 controls). The mean tHcy was on average 2.8 micromol/L (95% confidence interval [CI], 1.8-3.7) greater in the RVO cases compared with controls, but there was evidence of between-study heterogeneity (P<0.001, I(2) = 93%). There was funnel plot asymmetry suggesting publication bias. There was no evidence of association between homozygosity for the MTHFR C677T genotype and RVO (odds ratio [OR] 1.20; 95% CI, 0.84-1.71), but again marked heterogeneity (P = 0.004, I(2) = 53%) was observed.

CONCLUSIONS

There was some evidence that elevated tHcy was associated with RVO, but not homozygosity for the MTHFR C677T genotype. Both analyses should be interpreted cautiously because of marked heterogeneity between the study estimates and possible effect of publication bias on the tHcy findings.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Ocular vascular thrombotic events: a diagnostic window to familial thrombophilia (compound factor V Leiden and prothrombin gene heterozygosity) and thrombosis

In a 12-member, 3-generation kindred with conjoint inheritance of G1691A factor V Leiden (FVL) and G20210A prothrombin gene (PTG) mutations, identified through a proband with amaurosis fugax and his father with nonarteritic ischemic optic neuropathy (NAION), the authors' hypothesis was that ocular thrombosis was a diagnostic window to familial thrombophilia-thrombosis. The authors used polymerase chain reaction (PCR) measures for thrombophilia (FVL, PTG, C677T-A1298C methylenetetrahydrofolate reductase [MTHFR], platelet glycoprotein PLA1A2) and hypofibrinolysis (plasminogen activator inhibitor-1 4G4G). The 39-year-old white male proband, with amaurosis fugax and transient ischemic attacks (TIA), was found to be a compound heterozygote for FVL and PTG mutations. His symptoms resolved only after coumadin. His 44-year-old brother (deep venous thrombosis [DVT]) and 46-year-old sister (DVT, pulmonary embolus [PE]) were compound FVL-PTG gene heterozygotes. Of 4 asymptomatic children born to these 3 siblings, 2 were FVL heterozygotes and 2 PTG heterozygotes. The proband's 69-year-old father, with NAION and ischemic stroke, had PTG heterozygosity, familial high factor VIII, and compound MTHFR C677T-A1298C mutation with homocysteinemia. The proband's 61-year-old aunt had PTG heterozygosity, recurrent DVT, and mesenteric artery thrombosis. The proband's 67-year-old mother, free of thrombotic events, was a FVL heterozygote, had high factor VIII, and PAI-1 4G4G homozygosity. In this extended kindred, ocular thrombotic events (amaurosis fugax, NAION) were associated with variegated thrombotic events, including TIA, ischemic stroke, DVT, PE, and mesenteric artery thrombosis, and opened a diagnostic window to family screening and treatment for complex thrombophilias, which had previously been undiagnosed.

Management of acute central retinal artery occlusion

Central retinal artery occlusion (CRAO) is considered to be an acute stroke of the eye that results in profound visual loss. Spontaneous recovery rates are poor. Most CRAOs are caused by thromboembolism in the central retinal artery. Current standard therapies for CRAO that aim to restore perfusion to the retina and optic nerve head have not been shown to alter the natural course of the disease. Thrombolytic therapy for acute management of CRAO has shown promise in nonrandomized studies with regard to improving visual outcomes. A randomized controlled trial will be required to confirm the efficacy of thrombolytic therapy before it can be recommended for use in CRAO in daily clinical practice.

Relationship between thiolactonase activity and hyperhomocysteinemia according to MTHFR gene polymorphism in Tunisian Behçet's disease patients

BACKGROUND

Behçet's disease (BD) is a multisystemic immuno-inflammatory disorder. Inflammatory processes may cause lipid peroxidation, alteration of lipid profile and increase the risk of atherosclerosis. The aim of this study was to evaluate the association between thiolactonase (HTLase) activity and plasma homocysteine levels (tHcy) in a BD population and to investigate their association with methylenetetrahydrofolate reductase (MTHFR) 677C-->T genotype.

METHOD

A total of 35 BD patients were compared to 39 healthy volunteers.

RESULTS

Significantly higher tHcy levels associated with lower HTLase activities were found in BD patients as compared to healthy controls (p<0.001). These patients also exhibited lower values of triglycerides and high-density lipoprotein cholesterol (HDL-C). Homozygosity for the T allele of the MTHFR gene was more frequent in BD patients (14.3% vs. 7.7%). It was associated with significantly higher tHcy levels (16.9 micromol/L for n=17 vs. 13.1 micromol/L for n=18; p<0.05) and markedly lower HTLase activity (362.6+/-156.7 U/L vs. 414.2+/-180.2 U/L) for the (TT+CT) and CC genotypes, respectively. Moreover, HDL-C levels were inversely correlated with tHcy (r=-0.5; p=0.004) but positively associated with HTLase activity (r=0.374; p=0.038). These correlations were also present in several clinical manifestations, such as ocular, neurological involvement or thrombosis.

CONCLUSIONS

Homozygosity of the T allele of the MTHFR gene is prevalent in BD patients. High levels of tHcy associated with low HTLase activities may be one of the causes leading to thrombosis in BD patients.

Ocular vascular thrombotic events: central retinal vein and central retinal artery occlusions

We prospectively assessed associations of thrombophilia- hypofibrinolysis with central retinal vein occlusion (CRVO) (40 patients) and central retinal artery occlusion (CRAO) (9 patients). We used polymerase chain reaction measures for thrombophilia (factor V Leiden, prothrombin, C677T MTHFR, platelet glycoprotein PlA1/A2) and hypofibrinolysis (plasminogen activator inhibitor-1 4G4G). Serologic thrombophilia measures included protein C, protein S (total and free) and antithrombin III, homocysteine, lupus anticoagulant, anticardiolipin antibodies IgG-IgM, and factors VIII and XI. Serologic hypofibrinolysis measures included Lp(a) and plasminogen activator inhibitor activity. For comparison with 40 CRVO and 9 CRAO patients, 80 and 45 race-gender matched controls were studied. The factor V mutation was more common in CRVO (3/40, 8%) than controls (0/79, 0%), P = .036, as was high (>150%) factor VIII (12/40, 30%) versus (4/77, 5%), P = .0002. Low antithrombin III (<80%) was more common in CRVO (5/39, 13%) than in controls (2/73, 3%), P = .049. Homocysteine was high (> or =13.5 micromol/L) in 5/39 (13%) CRVO patients versus 2/78 controls (3%), P = .04. Three of 9 CRAO patients (33%) had low (<73%) protein C versus 2/37 controls (5%), P = .044. Two of 9 CRAO patients (22%) had high (> or =13.5 micromol/L) homocysteine versus 0/42 controls (0%), P =. 028. Four of 9 CRAO patients had the lupus anticoagulant (44%) versus 4/33 (12%) controls (P = .050). CRVO is associated with familial thrombophilia (factor V Leiden, factor VIII, low antithrombin III, homocysteinemia), and CRAO is associated with familial and acquired thrombophilia (low protein C, homocysteinemia, lupus anticoagulant), providing avenues for thromboprophylaxis, and triggering family screening.

Branch retinal artery occlusion associated with compound heterozygous genotype for methylenetetrahydrofolate reductase

We present a case in which mfERG and OCT helped to make a diagnosis of an old BRAO in the setting of compound heterozygous MTHFR genotype. A 44-year-old woman presented for evaluation of a 10 month history of persistently cloudy vision OS. She had been worked up previously for MS versus BRAO, and she was on coumadin, folate, and multivitamin at the time of presentation. The patient has a fraternal twin sister who was diagnosed with MS. Dilated fundus examination OS showed subtle inferior optic atrophy with slight narrowing of the inferotemporal retinal artery, and HVF test revealed a superonasal depression OS. mfERG also showed superonasal depression OS. Retinal origin of the chief complaint was further confirmed by OCT, which showed thinning of the NFL in the corresponding region of the retina OS. Coagulopathy evaluation revealed C677T/A1298C compound heterozygous genotype for MTHFR, and plasma homocysteine level after 6 months of folate and multivitamin supplementation was 10 microM (reference range 4-10 microM). The patient was diagnosed with BRAO and maintained on coumadin therapy.

Homocysteine: An activity marker in Behçet's disease?

BACKGROUND

Behçet's disease (BD) is a chronic multisystem inflammatory disorder commonly complicated by vascular thrombosis.

OBJECTIVE

In this study, we investigated whether hyperhomocysteinaemia, being a well known risk factor for atherothrombogenesis, is also a contributive risk factor for the pathogenesis and the activation of Behçet's disease.

METHODS

Sixty-four patients fulfilling the criteria of the International Study Group for Behçet's disease (48 males, 16 females, 33+/-8 years) were enrolled. They were separated into two groups with respect to activation features of Behçet's disease. Additionally, we collected the blood samples from 13 patients with BD in both active stage and in inactive stage. Twenty-six healthy individuals were included as a negative control group. Serum total homocysteine (Hcy) levels were determined by chemiluminescence immunoassay.

RESULTS

Mean serum homocysteine concentrations in total BD patients were significantly higher than in the healthy controls (11.7+/-4.6 versus 8.7+/-2.8micromol/L, p<0.01). Mean serum homocysteine concentrations in the active patients were significantly higher than in the inactive patients and the healthy controls (13.3+/-3.6; 10.8+/-5.0; 8.7+/-2.8micromol/L, respectively) (p<0.05 and p<0.001, respectively). There was no significant difference between the patients with inactive disease and the healthy controls. When the active and the inactive stage of 13 patients with BD were compared, we found that mean serum total homocysteine levels were higher in the active stage than in the inactive stage (p<0.05).

CONCLUSION

Hyperhomocysteinaemia may be responsible for the endothelial damage in BD and assumed to be a risk factor and a marker for activation of BD.

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.

Homocysteine, MTHFR C677T gene polymorphism, folic acid and vitamin B 12 in patients with retinal vein occlusion

Background

Many available data have suggested that hyperhomocysteinaemia, an established independent risk factor for thrombosis (arterial and venous), may be associated with an increased risk of retinal vein occlusion (RVO).

Aim of the study

To evaluate homocysteine metabolism in consecutive caucasian patients affected by RVO from Northern Italy.

Patients and Methods

69 consecutive patients from Northern Italy (mean age 64.1 ± 14.6 yy) with recent RVO, were tested for plasma levels of homocysteine (tHcy: fasting and after loading with methionine), cyanocobalamine and folic acid levels (CMIA-Abbot) and looking for MTHFR C677T mutation (Light Cycler-Roche) and compared to 50 volunteers, enrolled as a control group.

Results

Fasting levels of tHcy were significantly higher in patients than in controls: mean value 14.7 ± 7.7 vs 10.2 ± 8 nmol/ml. Post load levels were also significantly higher: mean value 42.7 ± 23.7 vs 30.4 ± 13.3 nmol/ml; Total homocysteine increase was also evaluated (i.e. Δ-tHcy) after methionine load and was also significantly higher in patients compared to control subjects: mean Δ-tHcy 27.8 ± 21.5 vs 21.0 ± 16 nmol/ml (normal value < 25 nmol/ml). Furthermore, patients affected by RVO show low folic acid and/or vitamin B12 levels, although differences with control group did not reach statistical significance. Heterozygous and homozygous MTHFR mutation were respectively in study group 46% and 29% vs control group 56% and 4%.

Conclusion

our data confirm that hyperhomocysteinaemia is a risk factor for RVO, and also that TT genotype of MTHFR C677T is more frequently associated with RVO: if the mutation per se is a risk factor for RVO remains an open question to be confirmed because another study from US did not reveal this aspect.

Hyperomocysteinemia is modifiable risk factor for thrombotic diseases. Therefore, a screening for tHcy plasma levels in patients with recent retinal vein occlusion could allow to identify patients who might benefit from supplementation with vitamins and normalization of homocysteine levels, in fasting and after methionine load.

Unruptured dural arteriovenous malformation of the transverse-sigmoid sinus presenting with focal symptoms and coma

We are presenting the case of a 63 year-old man with a dural arteriovenous malformation of the transverse sigmoid sinus who developed focal deficits followed by less localized symptoms such a disorientation, lethargy and eventually comatose status. Initial cerebral angiography showed retrograde filling of the cortical and deep cerebral venous system with marked delay in venous empting. Following embolization clinical symptoms completely cleared at the time that control angiography showed retrograde venous flow turning anterograde. Patient's symptoms recurred four months later when there was a relapse of retrograde cerebral venous drainage at the time he developed thrombosis of the superior longitudinal and right transverse sinuses. Sinus thrombosis and thrombosis of the central retinal artery were coincidental with hypercoagulability related to hyperhomocysteinemia. Since control angiography still showed persistence of the AV shunting radical excision of the involved dural sinuses was performed. The final outcome was excellent. The physiopathological mechanism responsible for neurological deficits in our patient most likely was ischemia of venous origin secondary to venous hypertension resulting from retrograde cerebral venous drainage. The clinical and angiographic presentation in few similar cases reported in the literature is reviewed.

Hyperhomocysteinemia in central retinal vein occlusion in young adults

PURPOSE

Several investigators have tried to assess the role of hyperhomocysteinemia and the 677C-T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene as risk factors in retinal vein occlusion with contrasting results. Aim of the study is to investigate the correlation between increased homocysteine plasma level and the homozygosity for the 677C-T mutation in the gene MTHFR in patients aged under 50 years affected by central retinal vein occlusion (CRVO).

METHODS

Through a prospective, case-control study, 31 patients under 50 years of age and diagnosed with CRVO were compared with two control groups. The first control group (GROUP I) included 31 subjects matched for age, sex, laboratory tests and the main risk factors for atherosclerosis. The second control group (GROUP II) consisted of 31 volunteers matched only for age and sex.

RESULTS

The mean homocysteine plasma level was 10.60 micromol/l in patients, 10.39 micromol/l in GROUP I and 9.34 micromol/l in GROUP II. There was no statistically significant difference between mean homocysteine plasma level in cases and in GROUP I. Mean homocysteine plasma level was lower in GROUP II than in patients, and the difference was statistically significant. Homozygosity for the 677C-T mutation in the MTHFR was found in four patients (12.9%), in five controls in GROUP I (16.1%) and in four controls in GROUP II (12.9%).

CONCLUSION

Our results support first of all the hypothesis that the homocysteine plasma level is not a primary and independent risk factor for central retinal vein occlusion, but is more likely a marker of atherosclerosis and the consequence of other well-established risk factors. Second, the importance of the design of the study is highlighted, since the obtained results differed on the basis of the considered control group. This feature could contribute to explain the contradictory results previously reported in the literature.

Prothrombin gene mutation G20210A, homocysteine, antiphospholipid antibodies and other hypercoagulable states in ocular thrombosis

The purpose of the present study was to determine whether using an extended panel of laboratory tests increases the detection of a hypercoagulable state in patients with ocular thromboses. Twenty consecutive patients with ocular thromboses (vein, artery, or choriocapillaris occlusions) underwent testing for activated protein C resistance/factor V Leiden, prothrombin G20210A, lupus anticoagulant, anticardiolipin antibodies, hyperhomocysteinemia, and deficiencies of protein C, protein S, and antithrombin. For each patient, we selected two age-matched and gender-matched individuals without ocular thromboses as controls. Sixteen of the 20 patients (80%) had one or more laboratory tests that supported a hypercoagulable condition. Prothrombin G20210A (P < 0.02) and hyperhomocysteinemia (P < 0.0006) were significantly more frequent in ocular thrombosis patients compared with controls. The most common condition was antiphospholipid antibody syndrome, present in 40% of patients (confirmed by repeat testing at least 6 weeks later), but this did not reach statistical significance compared with the controls. No patients with ocular thromboses had hereditary abnormalities of protein S, protein C, or antithrombin. In conclusion, an extended panel of laboratory tests improved the detection of a hypercoagulable state in ocular thromboses. Testing for homocysteine, antiphospholipid antibodies, and the prothrombin G20210A mutation should be considered in patients with ocular thromboses.

Hyperhomocysteinemia in patients with diabetes mellitus with and without diabetic retinopathy

OBJECTIVE

To evaluate the prevalence of hyperhomocysteinaemia in diabetic patients with no diabetic retinopathy (no DR), with non-proliferative diabetic retinopathy (NPDR) and with proliferative diabetic retinopathy (PDR).

RESEARCH DESIGN AND METHODS

This prospective, case-control study, included 179 diabetic patients and 156 age-matched controls with no diabetes and no history of ocular disease, who were undergoing routine physical checkups. Plasma homocysteine levels of all study participants were measured using high-performance liquid chromatography (HPLC). Hyperhomocysteinaemia was defined when homocysteine levels were higher than 15 micromol/l.

RESULTS

The mean plasma homocysteine level was 11.75+-0.24 in the control group,13.46+0.74 in the no DR group, 14.56 + 0.64 in the NPDR group and 15.86 + 1.34 in the PDR group. Mean homocysteine levels were significantly elevated in the NPDR and PDR groups compared to the control group(P = 0.001 and <0.0001, respectively). The prevalence of hyperhomocysteinaemia was also higher in the NPDR and PDR groups compared to the control group (P = 0.032 and 0.011, respectively). No statistically significant difference was found between the no DR and the control group.

CONCLUSIONS

Our findings suggest that hyperhomocysteinaemia may be associated with diabetic retinopathy and partially explain the increased risk of microvascular angiopathy occurring in these patients.

Plasma homocysteine and retinal artery occlusive disease: a case-control study

BACKGROUND

Previous studies have documented that elevated plasma homocysteine is a risk factor for cardiovascular, cerebrovascular and peripheral vascular disease. In a case-control study, we sought to determine whether elevated homocysteine (HCY) is a risk factor for retinal artery occlusive disease PATIENTS AND METHODS. Study subjects consisted of 20 patients (12 male, 8 female) (mean age, 55.8; range 42-70 years) with clinical and objective evidence of retinal vascular occlusive disease and 20 age-matched control subjects (9 males, 11 females) (mean age, 55.3 years; range 50-68 years). Hyperhomocysteinemia was defined as a plasma HCY level >15 micromol/L by HPLC. We also measured concentrations of triglycerides, and total cholesterol, LDL cholesterol, and HDL cholesterol.

RESULTS

The mean plasma HCY level in the patient group was 21.23+/-9.53 micromol/L (range, 8.00-43.99 micromol/L) compared with 12.59+/-4.97 micromol/L (range, 6.38 to 22.88 micromol/L) in the control group (P<0.008). There was no correlation between HCY and serum triglycerides or cholesterol levels within each group. We conclude that high plasma HCY level may be a risk factor for retinal artery occlusive disease.

Thrombophilia and stroke

Thrombophilia is defined as an enhanced tendency to form intravascular thrombi, which may be arterial or venous. Of the inherited thrombophilias, factor V Leiden and the prothrombin 20210 mutation have been associated with stroke, but this association is statistically significant only in children and adults under age 40. The risk of stroke in persons with these mutations is substantially increased by concomitant exposure to oral contraceptives. Hyperhomocystinemia is a major risk factor for stroke as well as Alzheimer's disease; persons with deficiencies of vitamin B12 or folic acid are especially vulnerable to these complications. Of the acquired thrombophilias, the antiphospholipid antibody syndrome is strongly associated with transient ischemic attacks, cerebral infarction, Sneddon syndrome, and dementia. The diagnosis of thrombophilia should be considered in stroke patients who are young, have a family history of thrombosis, suffer venous dural sinus thrombosis, or have recurrent strokes.

Meta-analysis of plasma homocysteine, serum folate, serum vitamin B12, and thermolabile MTHFR genotype as risk factors for retinal vascular occlusive disease

PURPOSE

To assess the role of plasma total homocysteine (tHcy) levels, serum folate and vitamin B(12)levels, and homozygosity for the thermolabile methylenetetrahydrofolate reductase genotype (TT) as risk factors for retinal vascular occlusive disease.

DESIGN

Meta-analysis of literature.

METHODS

A MEDLINE search was performed to identify all published case-control studies of plasma tHcy levels, serum folate and vitamin B(12) levels, and TT genotype in persons with retinal vascular occlusive disease. Main outcome measures included calculation of plasma tHcy, serum folate, and serum vitamin B(12) standard differences and odds ratios (OR) of TT genotype between cases and controls.

RESULTS

In total, 614 patients with all types of retinal vein occlusion had higher plasma tHcy levels than 762 control subjects (standard difference, 0.867; 95% confidence interval [CI] = 0.735, 0.999; P <.001). Plasma tHcy levels were also higher in 154 patients with retinal artery occlusion compared with 358 control subjects (standard difference 1.174; 95% CI = 0.947, 1.402; P <.001). Serum folates, but not vitamin B(12) levels, were lower in 287 patients with retinal vascular occlusion than in the same number of control subjects (standard difference, 0.508; 95% CI = 0.340, 0.675; P <.001; and -0.060; 95% CI = -0.024, 0.104; P =.474, respectively). Similar proportions of 690 patients with retinal vein occlusion and 2754 control subjects demonstrated the TT genotype (OR = 1.332; 95% CI = 0.995, 1.783; P =.054) as did 152 patients with retinal artery occlusions and 435 control subjects (OR = 1.716; 95% CI = 0.977, 3.014; P =.060).

CONCLUSIONS

Retinal vascular occlusion is associated with elevated plasma tHcy levels and low serum folate levels, but not serum vitamin B(12) levels and TT genotype. Until a prospective multicenter trial is undertaken, plasma tHcy levels and serum folate levels should be determined in patients with retinal vascular occlusions, and dietary supplementation with low doses of folate and vitamin B(12) should be considered for affected persons.

Hypercoagulable states and central retinal vein occlusion

Central retinal vein occlusion is a common cause of permanent visual loss. Work up and laboratory evaluation of patients requires the clinician to rule out hypertension, diabetes, hyperlipidemia, and glaucoma. Patients without an identifiable risk factor are often subject to extensive testing for primary and secondary thrombophilias. The purpose this paper is to review the literature to determine which of these tests is associated with central retinal vein occlusion. Antiphospholipid antibodies and elevated plasma homocysteine levels appear to be the tests associated most commonly in patients with central retinal vein occlusion in most controlled studies. Primary thrombophilias are found rarely when screening patients with central retinal vein occlusion. Extensive testing for thrombophilias is not warranted in the vast majority of patients with central retinal vein occlusion. Older patients with any of the common vascular risk factors do not require thrombophilic screening. By carefully selecting the patients who are evaluated for thrombophilias, the likelihood of finding true-positive tests is increased.

[Occlusion of the retinal artery]

The occlusion of the retinal artery usually leads to sudden and, in most cases, continual visual impairment of the affected eye. This is an uncommon illness with a variable progression. To date it has not been possible to develop a generally recommended therapy using prospective, randomised studies, as is the case for circulatory impairment in other organs. Due to this uncertainty, the treatment of a retinal arterial occlusion is regarded as an ophthalmological emergency and a challenge for the attending practitioner. In this overview, the actual state of our knowledge on the pathogenesis of occlusion of a retinal artery as well as current and new therapies are presented.

Genetic determinants of fasting and post-methionine hyperhomocysteinemia in patients with retinal vein occlusion

INTRODUCTION

Moderate hyperhomocysteinemia is considered a risk factor for both venous and arterial thrombosis. A prevalence of up to 30% of fasting hyperhomocysteinemia has been recently reported in patients with retinal vein occlusion (RVO) whereas conflicting data exist on the role of C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene as a risk factor for RVO. No report has been published on cystathionine beta-synthase (CBS) 844ins68 polymorphism (another genetic determinant of blood Hcy levels) in RVO patients. Moreover, scarce information is available on the usefulness of measuring homocysteine also after methionine loading to increase the diagnostic efficacy of hyperhomocysteinemia in RVO patients.

MATERIALS AND METHODS

In 55 consecutive patients with diagnosis of RVO and 65 matched controls, plasma fasting total homocysteine (Hcy) levels and CBS and MTHFR polymorphisms were evaluated. In patients with normal fasting Hcy levels, post-methionine Hcy levels were determined.

RESULTS

Moderate fasting hyperhomocysteinemia was detected in 18/55 patients (32.7%). In the remaining 37 patients, Hcy was measured again post-methionine loading (PML). Only 3/37 (8.1%) patients had PML hyperhomocysteinemia. Thus, the total prevalence of moderate hyperhomocysteinemia in this cohort of RVO patients was 21/55 (38.2%). The prevalence of homozygosity for C677T MTHFR genotype, but not that of heterozygosity for CBS844ins68, was significantly higher in RVO patients than in controls.

CONCLUSIONS

Differently from what has been reported for arterial and/or venous thrombosis, a single fasting Hcy measurement is able to detect most of RVO patients (85.7%) with moderate hyperhomocysteinemia. C677T MTHFR, but not CBS 844ins68, genotype may play a role as risk factor for RVO.

Hyperhomocysteinemia and retinal vascular occlusive disease

PURPOSE

Elevated plasma homocysteine is an independent risk factor for thrombosis and vascular disease. This prospective study compared plasma total homocysteine levels in patients with retinal vascular occlusive disease and in matched healthy controls.

METHODS

We measured plasma total homocysteine in 56 consecutive patients with recently diagnosed retinal vascular occlusive disease: 36 had central retinal vein occlusion, 12 branch retinal vein occlusion, and 8 retinal artery occlusion, and compared them with 59 age- and sex-matched healthy controls. Homocysteine levels were determined by high-performance liquid chromatography with electrochemical detection. Hyperhomocysteinemia was defined as a plasma homocysteine level above the 95th percentile in the control group (13.6 micromol/L).

RESULTS

Mean plasma total homocysteine levels were significantly higher in patients than controls (16.1 +/- 8.3 vs. 8.96 +/- 5.6 micromol/L p < 0.001). Mean homocysteine levels were significantly higher in the retinal vein occlusion and retinal artery occlusion groups than the control group (15.3 +/- 8.2 and 20.95 +/- 6.9 vs 8.96 +/- 5.6 micromol/L, p < 0.001). Estimates of the relative risk indicated that the risk of hyperhomocysteinemia was significantly higher in patients with retinal vascular occlusive disease than controls. Hyperhomocysteinemia was present in 37 (66.1%) of the 56 patients with retinal vascular occlusive disease but only 2 (3.4%) controls (odds ratio [OR] 47.5, 95% confidence interval [CI] 9.8-149.9). Hyperhomocysteinemia was present in 29 (60.4%) of the patients with retinal vein occlusion (OR 43.5, 95% CI 8.77-141.93) and in 6 (75%) patients with retinal artery occlusion (OR 85.5, 95% CI 7.49-1,173.1).

CONCLUSIONS

High plasma homocysteine is a risk factor for retinal vascular occlusive disease so it may be useful to measure homocysteine in the management of these patients. A randomized, controlled trial is required to study the effect of lowering with homocysteine folic acid and other B vitamins on the risk of recurrent vascular occlusion in the same eye or its development in the fellow eye.

Hyperhomocyst(e)inemia, but not methylenetetrahydrofolate reductase C677T mutation, as a risk factor in branch retinal vein occlusion

OBJECTIVE

To determine whether hyperhomocyst(e)inemia and methylenetetrahydrofolate reductase (MTHFR) C677T mutation are associated with branch retinal vein occlusion (BRVO).

DESIGN

Retrospective, case-control study.

PARTICIPANTS

The study cohort consisted of 84 consecutive patients with branch retinal vein occlusion and 84 controls, matched for age and gender.

MAIN OUTCOME MEASURES

Fasting plasma homocyst(e)ine, folate, and vitamin B(12) levels, MTHFR C677T genotypes.

RESULTS

Mean plasma homocyst(e)ine levels were significantly higher in patients than in controls (11.4 +/- 4.3 micromol/l vs. 9.9 +/- 2.8 micromol/l; P = 0.002). An increase of plasma homocyst(e)ine level by 1 micromol/l was associated with an odds ratio of 1.19 (95% confidence interval 1.06-1.34; P = 0.004). Mean plasma folate levels were significantly lower in patients than in the control group (4.5 +/- 2.1 ng/ml vs. 5.6 +/- 2.1 ng/ml; P = 0.007). The prevalence of the homozygous genotype of the MTHFR C677T mutation did not differ significantly between patients and controls.

CONCLUSIONS

Our results suggest that hyperhomocyst(e)inemia, but not homozygosity for the MTHFR C677T mutation, is associated with BRVO. Increased plasma homocyst(e)ine levels in our study are not the result of an increased prevalence of the homozygous genotype of MTHFR C677T mutation.

Serum homocysteine level is increased and correlated with endothelin-1 and nitric oxide in Behçet's disease

BACKGROUND/AIMS

Behçet's disease (BD) is a systemic inflammatory vasculitis of young adults with unknown aetiology, characterised by endothelial dysfunction and occlusion in both deep venous and retinal circulation. Ocular involvement occurs in 70% of cases and is characterised by periphlebitis, periarteritis, vascular occlusion, and thrombosis leading to blindness despite vigorous treatment. Endothelin-1 (ET-1) is a vasoconstricting peptide while nitric oxide (NO) is a relaxing molecule and both are released by endothelium for blood flow regulation. Homocysteinaemia is a newly defined term connected to the increased risk of atherothrombotic and atherosclerotic systemic and retinal vascular occlusive diseases, and its role in the course of BD has not been previously described. The authors aimed to detect serum total homocysteine (tHcy), ET-1, and NO in BD and to assess if tHcy, ET-1, and NO are associated with ocular BD or disease activity.

METHODS

43 consecutive patients with ocular (n = 27) or non-ocular (n = 16) BD (36.95 (SD 9.80) years, 22 male, 21 female) satisfying international criteria, and 25 age and sex matched healthy control subjects (37.88 (8.73) years, 13 male, 12 female) without a history of systemic or retinal venous thrombosis were included in this study. Patients were examined by two ophthalmologists with an interest in BD. Serum tHcy, ET-1, and NO concentrations were measured in both groups. Hyperhomocysteinaemia was defined as a tHcy level above the 95th percentile in the control group. Patients were divided into active and inactive period by acute phase reactants including alpha(1) antitrypsin, alpha(2) macroglobulin, erythrocyte sedimentation rate, and neutrophil count.

RESULTS

The overall mean serum tHcy, ET-1, and NO levels were significantly higher in patients with BD than in control subjects (tHcy = 15.83 (4.44) v 7.96 (2.66) ng/ml, p <0.001; ET-1 = 17.47 (4.33) v 5.74 (2.34) micromol/ml, p <0.001; NO = 37.60 (10.31) v 27.08 (7.76) micromol/l, p <0.001). Serum tHcy, ET-1, and NO levels were significantly higher in active patients than in inactive patients and control subjects. In addition, among patients with ocular BD, the mean tHcy levels were significantly increased and correlated with ET-1 and NO levels when compared with non-ocular disease and control subjects. All acute phase reactant levels were significantly higher in active period than in inactive stage and controls.

CONCLUSIONS

Elevated tHcy may be responsible for the endothelial damage in BD and may be an additional risk factor for the development of retinal vascular occlusive disease, contributing to the poor visual outcome in these patients. Assessment of tHcy may be important in the investigation and management of patients with BD, especially with ocular disease.

Cardiovascular and thrombophilic risk factors for central retinal vein occlusion

Retinal vein occlusion (RVO) is a relatively common disease that is often associated with a variety of systemic disorders including arterial hypertension, diabetes mellitus, dyslipidemia, and systemic vasculitis. There are various types of RVO, categorized on the basis of the site of occlusion and on the type of consequent vascular damage. Central retinal vein occlusion (CRVO) is the most frequently occurring and clinically relevant type of RVO. In addition to the well-known classical risk factors, new hemostasis-related ones have been investigated in patients affected by CRVO. The data concerning a number of parameters remain contradictory; yet, high levels of type 1 plasminogen activator inhibitor (PAI-1) and hyperhomocysteinemia appear to play a significant role in the pathogenesis of this disease. Although based on a limited number of studies, this new knowledge could eventually provide important indications regarding prognosis and therapeutic strategies.

Laboratory evaluation of hypercoagulable states in patients with central retinal vein occlusion who are less than 56 years of age

PURPOSE

To investigate whether hypercoagulability plays a role in thrombus formation in patients with central retinal vein occlusion (CRVO) who are less than 56 years of age.

DESIGN

Prospective, observational case series with retrospective comparative controls.

PARTICIPANTS AND CONTROLS

Participants included 55 consecutive patients with CRVO less than 56 years of age. The laboratory's age-matched control groups were used to compare results for the same tests.

METHODS

Fifty-five patients with CRVO less than 56 years old (mean age, 44 years) underwent laboratory evaluation for homocysteine, activated protein C resistance, protein C activity, protein S activity, antithrombin III activity, antiphospholipid antibodies, and anticardiolipin antibodies. The results were compared with previously drawn age-matched control groups obtained by the same laboratory for statistical significance.

MAIN OUTCOME MEASURES

Patients were considered to have a positive test if their results were outside the laboratory's established range.

RESULTS

Fifteen of 55 patients (27%) had one positive test result suggesting hypercoagulability. Compared with the control groups, these patients less than 56 years old with CRVO had a higher incidence of coagulation abnormalities by laboratory testing. Among the parameters tested, hyperhomocysteinemia and circulating antiphospholipid antibodies were significantly more common in the CRVO patients (P < 0.05) compared with age-matched controls.

CONCLUSIONS

Hypercoagulability may play a role in the pathogenesis of CRVO in patients less than 56 years old. The cause of CRVO remains multifactorial, and laboratory tests suggesting hypercoagulable states alone cannot account for the cause in most of these patients less than 56 years of age. The authors recommend examining blood pressure, intraocular pressure, complete blood count, glucose levels, and a lipid panel on all patients with CRVO. When tests for these common risk factors for CRVO are negative, consider ordering selected tests in young patients with CRVO to rule out thrombophilias, especially in patients with bilateral CRVO, a history of previous thrombosis, or family history of thrombosis.

Central retinal vein occlusion and thrombophilia

Central retinal vein occlusion is one of the commonest vascular diseases of the eye. The pathogenesis is multifactorial with both local factors and systemic diseases being aetiologically important. Many thrombophilic conditions have recently been identified and studies looking at their potential role in CRVO have been undertaken. The aim of this review is to critically appraise these studies as to date many have given conflicting results, making it far from clear what role thrombophilic conditions play in CRVO. It appears that hyperhomocysteinaemia and antiphospholipid syndrome are causes of CRVO and there is evidence that disorders causing hypofibrinolysis may also be important. The common hereditary thrombophilic conditions however do not appear to be strong risk factors but larger studies are needed for a definitive answer.

Thrombophilia as a cause for central and branch retinal artery occlusion in patients without an apparent embolic source

PURPOSE

To assess the prevalence of vascular risk factors and thrombophilias in central and branch retinal artery occlusion in patients in whom an embolic source is not apparent.

METHODS

The study group consisted of 21 consecutive patients with retinal artery occlusion (RAO) in whom Doppler ultrasonography of the carotid arteries and transthoracic or transoesophageal echocardiography were normal. Laboratory methods included polymerase chain reaction for detection of factor V G1691A, factor II G20210A and methylentetrahydrofolate reductase C677T mutations, assays of plasma levels of protein C, free protein S, antithrombin, fibrinogen and homocysteine; and tests for the presence of lupus anticoagulant and anticardiolipin antibodies. Controls for the laboratory tests were 243 healthy subjects.

RESULTS

Nine of the 21 (43%) patients had at least one thrombophilic marker: 4 were homozygous for MTHFR C677T, 1 was heterozygous for factor V G1691A, 1 had a high titre of IgM anticardiolipin, 2 were heterozygous for factor V G1691A and homozygous for MTHFR C677T, and 1 had lupus anticoagulant, a high titre of IgM anticardiolipin, homozygosity for MTHFR C677T and hyperhomocysteinaemia. An interaction between vascular risk factors and thrombophilias seemed important since out of 14 patients with hypertension, diabetes and/or hypercholesterolaemia 7 (50%) had a thrombophilia. Homozygous MTHFR C677T was a significant risk factor with odds ratio of 3.18 (95% CI 1.20-8.47). The prevalence of factor V G1691A was also higher in the RAO patients versus controls with an odds ratio of 2.36 (95% CI 0.63-8.88), but this value did not reach significance, probably due to the small sample size.

CONCLUSION

A search for thrombophilia in RAO is advisable in patients without evident source of emboli even when vascular risk factors are identified.

Thermolabile MTHFR genotype and retinal vascular occlusive disease

BACKGROUND

Raised levels of total plasma homocysteine (tHcy) are associated with an increased risk of retinal vascular occlusive disease. A thermolabile form of a pivotal enzyme in homocysteine metabolism, methylenetetrahydrofolate reductase (MTHFR), has been associated with vascular occlusive disease and raised tHcy levels. The relation between thermolabile MTHFR genotype, tHcy, and retinal vascular occlusive disease has not been determined.

METHODS

A retrospective case-control study involving hospital based controls and cases with retinal vascular occlusions in whom tHcy levels had been determined was undertaken. Genotyping for the MTHFR 677 C-T mutation that specifies the thermolabile form of the enzyme was performed by established methods in all subjects. The relation between homozygosity for thermolabile MTHFR genotype (TT), raised tHcy levels, and risk of retinal vascular occlusive disease was examined.

RESULTS

87 cases of retinal vascular occlusive disease (mean age 68.7 years) comprising 26 cases of retinal artery occlusion and 61 of retinal vein occlusion were compared with 87 controls (mean age 70.2 years). The TT genotype did not confer a significantly increased risk of retinal vascular occlusive disease. The mean tHcy level was significantly higher in the cases than in the controls (p<0.0001). Overall, and in both the cases and controls, the frequency of the TT genotype was higher in those with normal tHcy levels than in those with increased levels of tHcy. However, the TT genotype did not significantly alter the risk of increased tHcy levels in these patients.

CONCLUSIONS

The TT genotype is not associated with an increased risk of retinal vascular occlusive disease or increased tHcy levels in this group of elderly patients. In older patients, nutritional rather than genetic factors may be more important in increasing tHcy levels, a known risk factor for retinal vascular occlusive disease.

Systemic disorders associated with retinal vascular occlusion

Occlusions of the retinal arterial and venous circulations are common causes of severe visual decline and can affect all age groups. Acute retinal arterial obstruction is often associated with critical cerebrovascular and cardiovascular disease that may require systemic treatment. Retinal venous obstruction may be the presentation of significant systemic hypertension, diabetes mellitus, and a greater risk for cardiovascular morbidity. Additional metabolic and hematologic abnormalities have been identified in patients with retinal occlusive disease. The authors review recent advances in the study of systemic conditions associated with retinal vascular occlusions and offer guidelines for appropriate medical evaluation of patients with retinal occlusive disease.

Plasma total homocysteine and retinal vascular disease

PURPOSE

Hyperhomocysteinaemia has been linked to macrovascular disease. Our aim was to investigate whether there is a relationship between fasting plasma total homocysteine levels and retinal vascular disease.

METHODS

We measured the homocysteine levels in 70 patients with arterial or venous retinal vessel occlusion and compared them with the levels in 85 controls without evidence of ischaemic heart disease. Homocysteine levels were determined by high-performance liquid chromatography with electrochemical detection and compared after logarithmic transformation.

RESULTS

Homocysteine levels were found by univariate analysis (unpaired two-tailed t-test) to be significantly higher in the group with retinal artery occlusion than the group with retinal vein occlusion (p = 0.045) and in both groups compared with controls (18.4 and 13.8 vs 9.5 mumol/l; p = 0.0002 and < 0.0001, respectively). The controls, however, were significantly younger than the subjects (51.5 +/- 15.4 vs 66.2 +/- 11.9 years; p < 0.0001), but analysis of the results by age revealed significant differences between the groups and controls for the seventh decade (vein occlusions, p = 0.05) and for the eighth decade (artery occlusions, p = 0.037). Subgroup analysis of the retinal vessel occlusion group revealed significant differences in mean blood pressure between those with branch retinal vein occlusions (175/100 mmHg) and both those with central retinal vein occlusions (155/88 mmHg) and those with retinal artery occlusions (157/86 mmHg). Both vein occlusion subgroups also differed significantly with regard to homocysteine levels, branch < central (12.2 +/- 1.3 vs 15.0 +/- 1.6 mumol/l, p = 0.03). Multiple linear regression analysis revealed significant relationships between homocysteine levels and the presence of retinal vessel occlusion (p = 0.0002), serum creatinine (p = 0.001) and age (p = 0.003), but not gender.

CONCLUSIONS

We conclude that homocysteine may be a risk factor for retinal vascular disease and could be simply and cheaply treated with folate and vitamins B6 and B12.

Hyperhomocysteinemia: a risk factor for central retinal vein occlusion

PURPOSE

Previous studies have documented that elevated plasma homocysteine level is a risk factor for vascular disease. This study was performed to determine whether hyperhomocysteinemia is a risk factor for central retinal vein occlusion.

METHODS

In a case-control study, data from 74 patients with documented central retinal vein occlusion were reassessed. Control subjects consisted of individuals referred to the same clinic for assessment of a nonretinal vascular disease. Hyperhomocysteinemia was defined as a total plasma homocysteine level above the 95th percentile in the control group.

RESULTS

The mean total plasma homocysteine level was 11.58 +/- 4.67 micromol/l (range, 5-26 micromol/l) for cases, and 9.49 +/- 2.65 micromol/l (range, 5-20 micromol/l) for control subjects. Of the 74 patients with a central retinal vein occlusion, 16 (21.6%) had total plasma homocysteine levels above the 95th percentile in the control group (odds ratio, 6.53; 95% confidence interval, 1.81-23.50; P =. 003). Hyperhomocysteinemia was present in five (55%) of the nine individuals with bilateral disease, nine (30%) of the 30 patients with ischemic occlusions, and 45 (31%) of the 83 eyes with severe visual loss.

CONCLUSION

Hyperhomocysteinemia is a risk factor for central retinal vein occlusion and may suggest a poor prognosis in patients with central retinal vein occlusion.