MODERATE HYPERHOMOCYSTEINEMIA AND EARLY-ONSET CENTRAL RETINAL VEIN OCCLUSION

Ocular manifestations in patients with inborn errors of intracellular cobalamin metabolism: a systematic review

Inherited disorders of cobalamin (cbl) metabolism (cblA-J) result in accumulation of methylmalonic acid (MMA) and/or homocystinuria (HCU). Clinical presentation includes ophthalmological manifestations related to retina, optic nerve and posterior visual alterations, mainly reported in cblC and sporadically in other cbl inborn errors.We searched MEDLINE EMBASE and Cochrane Library, and analyzed articles reporting ocular manifestations in cbl inborn errors. Out of 166 studies a total of 52 studies reporting 163 cbl and 24 mut cases were included. Ocular manifestations were found in all cbl defects except for cblB and cblD-MMA; cblC was the most frequent disorder affecting 137 (84.0%) patients. The c.271dupA was the most common pathogenic variant, accounting for 70/105 (66.7%) cases. One hundred and thirty-seven out of 154 (88.9%) patients presented with early-onset disease (0-12 months). Nystagmus and strabismus were observed in all groups with the exception of MMA patients while maculopathy and peripheral retinal degeneration were almost exclusively found in MMA-HCU patients. Optic nerve damage ranging from mild temporal disc pallor to complete atrophy was prevalent in MMA-HCU.and MMA groups. Nystagmus was frequent in early-onset patients. Retinal and macular degeneration worsened despite early treatment and stabilized systemic function in these patients. The functional prognosis remains poor with final visual acuity < 20/200 in 55.6% (25/45) of cases. In conclusion, the spectrum of eye disease in Cbl patients depends on metabolic severity and age of onset. The development of visual manifestations over time despite early metabolic treatment point out the need for specific innovative therapies.

Vitamin B12 and Folate as Risk Factors for Retinal Vein Occlusion: A Meta-Analysis

PURPOSE

To evaluate the association between serum vitamin B12/folate and retinal vein occlusion (RVO).

METHODS

A comprehensive search of the PubMed database was performed, which identified 271 abstracts to be screened. Ten studies met our inclusion criteria and a meta-analysis of these comparative case-control studies was performed on the mean ± standard deviation serum vitamin B12 and folate levels, without language restrictions. Nine studies with 720 patients with RVO and 613 controls were included in the meta-analysis for vitamin B12, and 10 studies with 784 patients with RVO and 677 controls in the meta-analysis for folate.

RESULTS

There was no statistically significant difference between patients with RVO and controls in serum vitamin B12 levels (mean difference: - 40.25 pg/mL, p = 0.28), either central RVO (mean difference: - 18.24 pg/mL, p = 0.71) or branch RVO (mean difference: - 23.56 pg/mL, p = 0.48). On the contrary, the plasma folate level was significantly lower in RVO patients than in controls (mean difference: - 1.34 ng/mL, p = 0.001), as well as in patients with CRVO compared to controls (mean difference: - 1.48 ng/mL, p = 0.006), but not in BRVO patients (mean difference: - 0.72 ng/mL, p = 0.11).

CONCLUSIONS

RVO is associated with low serum folate levels, but not with serum vitamin B12 levels.

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.

Ocular disease in the cobalamin C defect: a review of the literature and a suggested framework for clinical surveillance

The association between combined methylmalonic acidemia and homocystinuria of cblC type (cobalamin C defect, cblC) and ocular disease is now well recognized, and is a significant component of morbidity and disability associated with the condition. In this review, through collation of historically reported cases of early- and late-onset cblC and previously unreported cases, we have attempted to characterize the epidemiology, clinical features, and pathomechanisms of individual ocular features of cblC. These data suggest that maculopathy and nystagmus with abnormal vision are extremely common and affect the majority of children with early-onset cblC, usually before school age; strabismus and optic atrophy are also seen at relatively high frequency. The timing of progression of macular disease may coincide with a critical period of postnatal foveal development. Maculopathy and retinal disease may be subclinical and show only partial correlation with the extent of visual deficits, and visual deterioration may be relentlessly progressive in spite of aggressive treatment of biochemical abnormalities. In later-onset forms of the disease, visual loss and ocular complications appear to be infrequent. Finally, we discuss investigational strategies in diagnosing and characterizing eye disease in individuals with cblC, explore possible therapeutic avenues that may attenuate progression and severity of eye disease, and propose a clinical surveillance guideline for monitoring progression of ocular disease in children and adults with cblC.

Hyperhomocysteinemia, a biochemical tool for differentiating ischemic and nonischemic central retinal vein occlusion during the early acute phase

PURPOSE

The purpose of the study was to differentiate ischemic central retinal vein occlusion (CRVO) from nonischemic CRVO during the early acute phase using plasma homocysteine as a biochemical marker.

METHODS

Fasting plasma homocysteine, serum vitamin B12, and folate levels were measured in 108 consecutive unilateral elderly adult (age >50 years) ischemic CRVO patients in the absence of local and systemic disease and compared with a total of 144 age and sex matched nonischemic CRVO patients and 120 age and sex matched healthy control subjects.

RESULTS

Homocysteine level was significantly increased in the patients with ischemic CRVO in comparison with nonischemic CRVO patients (p = 0.009) and also in comparison with control subjects (p < 0.001). Analysis also showed that hyperhomocysteinemia was associated with increased incidence of ischemic CRVO (odds ratio, 18) than that for nonischemic CRVO (odds ratio, 4.5). Serum vitamin B12 and folate levels were significantly lower (p < 0.001) in CRVO patients compared to the control but were not significantly different between nonischemic and ischemic CRVO patients (p > 0.1).

CONCLUSIONS

Hyperhomocysteinemia can be regarded as useful in differentiating nonischemic and ischemic CRVO during the early acute phase in absence of local and systemic disease in the elderly adult (age >50 years) population.

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

Background

To evaluate the role of plasma total homocysteine (tHcy) and homozygosity for the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) C677T genotype in the risk of retinal vein occlusion (RVO).

Methods

Relevant studies were selected through an extensive search of PubMed, EMBASE, and the Web of Science databases. Summary weighted mean differences (WMDs) or odds ratios (ORs) and 95% confidence intervals (CI) were calculated with a random-effects model.

Results

Forty-two studies with 6445 participants were included in this updated systematic review and meta-analysis. The mean plasma tHcy level in the RVO patients was significantly higher than in the controls (WMD =2.13 μmol/L; 95% CI: 1.29 to 2.98, P < 0.001), but there was evidence of between-study heterogeneity (P < 0.001). No significant association between MTHFR C677T genotype and RVO was found under all genetic models.

Conclusion

There was some evidence that plasma tHcy is associated with an increased risk of RVO. There was no evidence to suggest an association between homozygosity for the MTHFR C677T genotype and RVO.

Risk factors, antithrombotic treatment and outcome in retinal vein occlusion: an age-related prospective cohort study

OBJECTIVES

Antithrombotic treatment for retinal vein occlusion (RVO) is controversial, although RVO has been surmised as a predictor of a subsequent vascular event. We aimed to evaluate risk factors, the effects of antithrombotic therapy and the occurrence of subsequent vascular events in patients with a first episode of RVO, according to age of RVO onset.

METHODS

In this prospective cohort study, patients with central (CRVO) and branch RVO (BRVO) confirmed by fluorescein angiography were studied; they were divided according to age. Cardiovascular risk factors and thrombophilia were evaluated. Anticoagulants or aspirin were given for at least 3 months. Patients were followed every 6-12 months and vascular events were recorded.

RESULTS

One hundred CRVO and 32 BRVO patients were enrolled. Five of 60 (8.3%) patients <50 yr and 4/72 (5.5%) over 50 yr had a hereditary thrombophilic defect. One or more cardiovascular risk factors were found in 35 (58%) patients of the younger group, and in 66 (91%) of the older group (P < 0.001). Antithrombotic treatment led to both a satisfactory recanalization of occluded veins and visual acuity improvement especially in younger patients. Vascular events occurred in 19 (14%) cases after 4 ± 3.3 yr from RVO, more frequently in older than in younger patients (22% vs. 5%, P = 0.005).

CONCLUSIONS

Distribution of cardiovascular, but not of thrombophilic risk factors seems to be influenced by age in RVO patients. Patients with a first RVO, especially those >50 yr, are likely at risk of a subsequent vascular event.

Association between B-group vitamins and venous thrombosis: systematic review and meta-analysis of epidemiological studies

A homocysteine-independent role for B-group vitamins on venous thrombosis (VT) development has been reported. However, related research findings remain inconsistent. PUBMED, EMBASE, and COCHRANE databases were searched to collect information on all eligible studies to make a meta-analysis about the relationship between B-group vitamins and VT. Literature search results did not suggest a correlation between thiamin, pantothenic acid, niacin, or riboflavin with VT. Based on their correlations in the literature, folic acid, vitamin B12, B6 were considered in the meta-analysis and systematic review. Significant standardized mean differences were obtained for plasma folic acid (-0.55; 95% CI, -0.75 to -0.36) and vitamin B12 (-0.34; 95% CI, -0.55 to -0.13). Reduced levels of folic acid and vitamin B12 may be independent risk factors of VT. Moreover, a qualitative systematic review indicated that low level of vitamin B6 was an independent risk factor of VT. Randomized clinical studies of B-group vitamins supplementation showed varying results on VT prevention. Multivitamin supplementation for VT prevention, regardless of homocysteine level, would be of interest. Further prospective clinical studies are needed to provide additional evidence on the clinical benefits of B-group vitamin supplementation for VT.

The Association between Serum Homocysteine Levels and Retinopathy of Prematurity

Objective:

To evaluate the relationship between serum total homocysteine levels and retinopathy of prematurity (ROP).

Methods:

This prospective case-control study involved premature infants diagnosed with ROP 4 weeks after birth (cases); controls were premature infants not developing ROP during follow-up. Fasting serum total homocysteine concentrations were determined in all participants 4 weeks after birth, using high performance liquid chromatography.

Results:

A total of 45 and 35 infants were included in the case and control groups, respectively. The mean ± SD (range) serum total homocysteine levels were 10.36 ± 1.72 μmol/l (7.45 - 14.84) in infants with ROP and 8.41 ± 2.12 μmol/l (5.56 - 13.90) in controls. This difference was statistically significant. Mean ± SD total homocysteine levels were higher in infants with more severe ROP (11.45 ± 1.76 μmol/l) compared with mild ROP (9.92 ± 1.56 μmol/l).

Conclusions:

Elevated serum total homocysteine levels are associated with the development of ROP in premature infants. Further studies with larger patient populations are required, to improve understanding of the relationship between homocysteine and ROP development.

Thrombophilia and retinal vascular occlusion

Purpose

The purpose of this research was to assess associations of thrombophilia with central retinal vein occlusion (CRVO), central retinal artery occlusion (CRAO), and amaurosis fugax (AF); to evaluate outcomes of normalizing high homocysteine; and to study CRVO, CRAO, and AF developing in estrogens/estrogen agonists in women subsequently shown to have thrombophilia.

Methods

Measures of thrombophilia–hypofibrinolysis were obtained in 132 CRVO cases, 15 CRAO cases, and 17 AF cases. Cases were compared to 105 healthy control subjects who did not differ by race or sex and were free of any ophthalmologic disorders. All cardiovascular disease (CVD) risk factors were compared to healthy general populations.

Main outcome measures

The main outcome measure of this study was thrombophilia.

Results

CRVO cases were more likely than controls to have high homocysteine (odds ratio [OR] 8.64, 95% confidence intervals [CI]: 1.96–38), high anticardiolipin immunoglobulin M (IgM; OR 6.26, 95% CI: 1.4–28.2), and high Factor VIII (OR 2.47, 95% CI: 1.31–7.9). CRAO-AF cases were more likely than controls to have high homocysteine (OR 14, 95% CI: 2.7–71.6) or the lupus anticoagulant (OR 4.1, 95% CI: 1.3–13.2). In four of 77 women with CRVO (two found to have high homocysteine, two with inherited high Factor XI), CRVO occurred after starting estrogen–progestins, estrogen–testosterone, or estrogen agonists. In one of eight women with CRAO found to have high anticardiolipin antibody IgG, CRAO occurred after starting conjugated estrogens, and AF occurred after starting conjugated estrogens in one of eleven women with AF (inherited protein S deficiency). Therapy for medians of 21 months (CRVO) and 6 months (CRAO-AF) was 5 mg folic acid, 100 mg B6, and 2000 mcg/day B12 normalized homocysteine in 13 of 16 (81%) CRVO cases and all five CRAO-AF cases with pretreatment hyperhomocysteinemia. The CRVO cases had an excess of hypertension; CRAO-AF cases had an excess of type 2 diabetes and hypertension.

Conclusion

Treatable thrombophilia, hyperhomocysteinemia in particular, is more common in RVO cases than in normal controls. RVO occurs after estrogens or estrogen agonists were administered in women subsequently shown to have thrombophilia.

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).

Atherosclerotic and thrombophilic risk factors in patients with ischemic central retinal vein occlusion

PURPOSE

To investigate atherosclerotic and thrombophilic risk factors in patients affected by acute ischemic and nonischemic central retinal vein occlusions (CRVOs).

METHODS

One hundred and three patients with acute unilateral CRVO (41 ischemic and 62 nonischemic) were studied. The frequency of traditional cardiovascular risk factors was assessed, and the plasma levels of a variety of thrombophilic markers were measured. Univariate logistic regression was performed to determine risk factors for ischemic CRVO.

RESULTS

Arterial hypertension, hypercholesterolemia, postmethionine hyperhomocysteinemia (HHcy), elevated factor VIII, and reduced folic acid and B6 plasma levels were more frequent in patients with ischemic CRVO than in those with nonischemic CRVO (P = 0.030, P = 0.025, P = 0.011, P < 0.001, P < 0.001, and P = 0.044, respectively). Risk factors for ischemic CRVO were arterial hypertension (odds ratio [OR], 3.22; 95% confidence interval [CI], 1.13-9.21; P = 0.037), hypercholesterolemia (OR, 3.03; 95% CI, 1.06-8.65; P = 0.042), reduced folic acid levels (OR, 6.77; 95% CI, 1.59-28.79; P = 0.011), and elevated FVIII levels (OR, 6.17; 95% CI, 2.56-14.82; P < 0.001). Postmethionine HHcy was associated with low folic acid levels (r = -0.413; P = 0.007; OR, 9.33; 95% CI, 2.06-42.18; P = 0.005).

CONCLUSION

The results of the present study suggest that some atherosclerotic and thrombophilic risk factors may increase the risk of having an ischemic form of CRVO.

Complete deficiency of methylenetetrahydrofolate reductase in mice is associated with impaired retinal function and variable mortality, hematological profiles, and reproductive outcomes

Severe deficiency of methylenetetrahydrofolate reductase (MTHFR) with homocystinuria can result in early demise or later-onset neurological impairment, including developmental delay, motor dysfunction, and seizures. We previously characterized BALB/c Mthfr (-/-)mice as a model for this disorder and have recently backcrossed the disrupted allele onto the C57Bl/6 background to examine the variable phenotypes in MTHFR deficiency. Compared with BALB/c Mthfr (-/-)mice, C57Bl/6 Mthfr (-/-)mice have enhanced survival rates (81% vs 26.5%). Four-day-old BALB/c mutant pups had lower body, brain, and spleen weights relative to their wild-type counterparts compared with C57Bl/6 mutants. Pregnant BALB/c Mthfr (+/-)mice had increased resorptions and embryonic delays compared with wild-type littermates, whereas these outcomes in C57Bl/6 c Mthfr (+/-)mice were similar to those of wild-type C57Bl/6 mice. BALB/c-mutant pups had altered hematological profiles (higher hematocrit, hemoglobin, and white blood cell counts, with lower platelet counts) compared with C57Bl/6 mutants. Mutants of both strains had similar degrees of hepatic steatosis, hepatic activity of betaine:homocysteine methyltransferase, and altered cerebellar histology. Electroretinograms (ERG) in C57Bl/6 Mthfr (-/-)mice revealed decreased amplitude of scotopic and photopic waves in 6-week-old mice, with normalized ERGs at 13 weeks. Plasma homocysteine was modestly higher in C57Bl/6 compared with BALB/c mice. Our results emphasize the variable presentation of MTHFR deficiency in different genetic backgrounds and suggest that plasma homocysteine is not a predictor of severity. In addition, our novel findings of decreased spleen weights, thrombocytopenia, and impaired retinal function warrant investigation in patients with severe MTHFR deficiency or other forms of homocystinuria.

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.

Comparative analysis of homocysteine concentrations in patients with retinal vein occlusion versus thrombotic and atherosclerotic disorders

The objectives of the present study were to determine the concentrations of plasma homocysteine in a large (n = 562) cohort of patients with retinal vein occlusion (RVO) and to compare them with the values observed in other vascular thrombotic and atherosclerotic conditions. Results were compared with those observed in patients with deep vein thrombosis (n = 1700), pulmonary embolism (n = 542), transient ischemic attack (n = 1301), cerebrovascular accident (n = 1299), myocardial infarction (n = 3087), as well as peripheral artery occlusive disease (n = 1946). No differences were found between the age-adjusted estimated marginal mean +/- SE for homocysteine concentrations in individuals with RVO and in those who had other atherosclerotic and atherothrombotic diseases The respective concentrations for RVO, deep vein thrombosis, pulmonary embolism, transient ischemic attack, cerebrovascular accident, myocardial infarction, and peripheral artery occlusive disease were 13.8 +/- 0.4, 14.7 +/- 0.3, 14.3 +/- 0.5, 14.2 +/- 0.3,14.6 +/- 0.3, 13.8 +/- 0.2, 14.4 +/- 0.2 pmol/l for men and 11.4 +/- 0.4, 10.7 +/- 0.2, 10.8 +/- 0.3, 10.8 +/- 0.2, 11.8 +/- 0.2, 11.2 +/- 0.2 pmol/l for women. In conclusion, the concentrations of homocysteine observed in patients with RVO are similar to those detected in other thrombotic and atherosclerotic vascular disorders. In view of the fact that this is a common disorder of the elderly, increased homocysteine concentrations often reported in patients with RVO could reflect the underlying atherothrombotic condition and might not necessarily be specifically related to the RVO per se. This information is relevant in researching the potential etiopathologic role, if any, of increased homocysteine concentrations in RVO.

Atherosclerotic and thrombophilic risk factors in patients with recurrent central retinal vein occlusion

PURPOSE

Atherosclerotic and thrombophilic risk factors may be causes of central retinal vein occlusion (CRVO). The aim of this study was to evaluate the prevalence of the aforesaid risk factors in patients with recurrent CRVOs and patients with a single episode of CRVO.

METHODS

Seventeen patients with recurrent CRVO and 30 with a single episode of CRVO were enrolled. The atherosclerotic risk factors investigated were hypertension, diabetes, smoking, and dyslipidemia. Specific laboratory tests for the following thrombophilic markers were performed: homocystinemia (Hcy), lipoprotein (a), factor VIII, factor II G20210A and factor V G1691A polymorphisms, lupus anticoagulant, anticardiolipin antibodies, plasminogen activator inhibitor-1, and deficit of vitamins B6, B12, and folic acid. A multivariate analysis, adjusted for age, gender, traditional and thrombophilic risk factors, was performed. Statistical significance was set at p<or=0.05.

RESULTS

Hypercholesterolemia, hypertriglyceridemia, fasting, and postmethionine hyperhomocysteinemia (HHcy) were more prevalent in recurrent CRVO patients (p<0.001, p<0.001, p=0.006, and p=0.005, respectively). At multivariate analysis, hypercholesterolemia (OR: 5.04, 95% CI 1.39-18.17; p=0.025), hypertriglyceridemia (OR: 5.60, 95% CI 1.52-20.61; p=0.017), fasting HHcy (OR: 5.77, 95% CI 1.39-23.89; p=0.028), and postmethionine HHcy (OR: 10.88, 95% CI 2.50-47.42; p=0.002) were found to be significantly associated with recurrent CRVO.

CONCLUSIONS

Dyslipidemia and hyperhomocysteinemia are independent risk factors for the occurrence of recurrent CRVO. A complete assessment of atherosclerotic and thrombophilic risk factors in CRVO patients. In addition, the need for a specific treatment is suggested.

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.

Serum PON1 arylesterase activity in relation to hyperhomocysteinaemia and oxidative stress in young adult central retinal venous occlusion patients

AIM

To estimate the arylesterase activity of serum paraoxonase-1 (PON1-ARE), which is reported to have an antioxidant and antiatherogenic potential and to correlate with plasma homocysteine (Hcys) and plasma TBARS in young adult central retinal venous occlusion (CRVO) patients.

METHODS

A case-control prospective study carried out in 10 CRVO patients (mean age 27+/-5 years; 7 males, 3 females) and 20 healthy controls (mean age 29+/-5 years; 15 males, 5 females).

RESULTS

The CRVO patients showed a significantly lowered serum PON1-ARE activity (P=0.009) along with a significant increase in the levels of plasma Hcys (P=0.018) when compared to the control subjects. There was a negative correlation between serum PON1-ARE and plasma Hcys levels (P=0.058) as well as between PON1-ARE and plasma TBARS levels (P=0.001) in the CRVO patients.

CONCLUSION

This is the first report of lowered serum PON1-ARE level as a risk factor for CRVO (OR= 1.108, CI=0.914, 1.314; P=0.296), which is found to correlate with oxidative stress.

Low vitamin B6 and folic acid levels are associated with retinal vein occlusion independently of homocysteine levels

Retinal vein occlusion (RVO) is one of the most common retinal vascular disorders. During the last years, high levels of homocysteine (Hcy) have been demonstrated to be an independent risk factor for RVO. Aim of this study was to investigate the association among circulating B-group vitamins, Hcy and RVO. Thus, we studied 262 RVO patients and 262 age- and sex-comparable healthy subjects. Serum vitamin B6 was measured by HPLC, serum folic acid and vitamin B12 by radioimmunoassay and plasma Hcy by FPIA. Blood levels of vitamin B6, folate and Hcy, but not of vitamin B12, were found to be significantly different in patients as compared to healthy subjects. At the univariate analysis, the lowest tertile of vitamin B6 [odds ratio (OR) 4.03; 95% confidence interval (CI) 2.58-6.31; P<0.0001)] and folate (OR 6.13; 95% CI 3.85-9.76, P<0.0001), and the highest tertile of Hcy (OR 8.08; 95% CI 5.05-12.92, P<0.0001) were found to be significantly associated with RVO. Moreover, at multivariate analysis, after adjustment for traditional cardiovascular risk factors, Hcy, and circulating levels of vitamins, respectively, the lowest tertile of vitamin B6 (OR 3.29; 95% CI 1.89-5.70, P<0.0001) and folate (OR 5.41; 95% CI 3.08-9.51, P<0.0001) and the highest tertile of Hcy (OR 2.58; 95% CI 1.12-5.94, P<0.0001) maintained their significant association with RVO. In conclusion, the present study documents, on a large sample of patients, that low vitamin B6 levels, low folic acid levels and elevated Hcy levels are each independently associated with RVO.

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.