Genetic thrombophilia in patients with retinal vascular occlusion

High prevalence of thrombophilic risk factors in patients with central retinal artery occlusion

INTRODUCTION

Central retinal artery occlusion (CRAO) is a common cause of blindness and visual morbidity. In the majority of cases, it is related to thrombotic embolism. Nevertheless, the role of inherited or acquired thrombophilic risk factors in CRAO pathogenesis has not been comprehensively studied.

METHODS

In 126 CRAO patients (66 [52.4%] men, median age 55 [range: 18-80] years) and 107 matched controls (56 [52.3%] men, median age 53 [range: 34-78] years) we evaluated classical atherosclerotic risk factors, including serum lipid profile and glucose level, analyzed intima-media complex thickness (IMT) of external carotid arteries, and performed transthoracic echocardiography. Furthermore, we established the prevalence of inherited and acquired thrombophilic risk factors, such as factor V Leiden (FVL) and prothrombin 20210 G/A genetic variants, plasma activity of factor (F) VIII, protein C and antithrombin activity, and free protein S levels. We also assessed the presence of antiphospholipid antibodies (APLA) and evaluated blood homocysteine in all enrolled subjects. Additionally, we estimated the occurrence of Val34Leu polymorphism of the A subunit of coagulation factor XIII (FXIII-A) in both groups as a potential thrombosis-protecting factor.

RESULTS

Among traditional atherosclerotic risk components, obesity/overweight and hypercholesterolemia were the most common in the CRAO group and occurred in 103 (81.7%) and 85 (67.5%) patients, respectively. CRAO patients also had elevated IMT and altered echocardiographic parameters, indicating diastolic cardiac dysfunction. In thrombophilia investigations, at least one laboratory risk factor occurred in 72.2% (n = 91) of CRAO patients, with APLA as the most frequent, detected in 38.1% (n = 48) of them (almost seven times more frequent than in controls, p < 0.001). Deficiencies in protein C activity and free protein S levels were also common in the CRAO group, reported in 17.5% (n = 22) and 19.8% (n = 25) of patients, respectively. Interestingly, among two analyzed prothrombotic genetic variants, only the FVL was related to CRAO, with the allelic frequency 2.4 times more prevalent than in controls (p = 0.044). Finally, the CRAO group was characterized by hyperhomocysteinemia, almost twice as common as in controls (p = 0.026). Antithrombin deficiency, elevated FVIII, and FXIII-A Val34Leu polymorphism were not associated with CRAO.

CONCLUSIONS

Our findings suggest that thrombophilia plays a vital role in the pathogenesis of CRAO. Thus, proper laboratory screening should be considered in the primary and secondary prevention of those episodes, with implementing appropriate therapy as needed.

Factor V G1691A is associated with an increased risk of retinal vein occlusion: a meta-analysis

We performed a meta-analysis to investigate the association between the Factor V G1691A polymorphism and the risk of retinal vein occlusion (RVO). This analysis included 37 studies involving 2,510 cases and 3,466 controls. Factor V G1691A was associated with an increased risk of RVO in the allele, heterozygote, dominant, and carrier models (PA < 0.001, odds ratios >1), but not the homozygote or recessive models (PA > 0.05). Similar results were observed in a meta-analysis of central retinal vein occlusion (CRVO) and when comparing Caucasian subgroups to population-based controls. These data demonstrate that the G/A genotype of Factor V G1691A is associated with an increased risk of RVO/CRVO in a Caucasian population.

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

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

Prevalence of thrombophilic genetic factors among patients with retinitis pigmentosa

PURPOSE

To determine the prevalence of thrombophilic factors in patients with retinitis pigmentosa (RP).

METHODS

Fifty consecutive patients with RP and 50 controls matched by age and gender were tested for the presence of the following mutations: factor II (GA20210), factor V Leiden (GA1691), methylenetetrahydrofolate reductase (CT677), factor XIIIa (Val→Leu), β-fibrinogen (GA455), tumor necrosis factor receptor (TNFRII) (M196R), plasminogen activator inhibitor-1 (PAI-1) (4 G/5 G), and plasminogen activator inhibitor-1 (PAI-1) (GA844).

RESULTS

The following heterozygous mutations were found in patients/controls: factor V Leiden (12/14), factor XIIIa (20/30), methylenetetrahydrofolate reductase 677 TT (48/52), β-fibrinogen GA455 (36/36), TNFRII (M196R) (40/42), PAI-1 4 G/5 G (40/48), and PAI-1 GA844 (50/52). The difference between patients with RP and the control group was not statistically significant for the prevalence of any of the studied factors (P > 0.05).

CONCLUSION

In this study, thrombophilic mutations were not increased in patients with RP. Thrombophilic mutations do not seem to be risk factors for RP. Routine investigation of hereditary thrombophilia in these patients is not justified.

Risk Factors and Treatment Strategies in Patients With Retinal Vascular Occlusions

Retinal vein occlusion (RVO) and retinal artery occlusion (RAO) cause significant visual impairment. The role of thrombophilia and cardiovascular testing is uncertain, and optimal treatment strategies have not been determined. We reviewed medical records of 39 patients with RVO and RAO (23 women and 16 men). Thrombophilia and cardiovascular evaluations were performed and outcomes were reviewed. In all, 24 (61.5%) patients had at least 1 thrombophilia. Elevated factor VIII levels were found in RVO (n = 5) but not in RAO. There are no other significant differences in thrombophilias in RVO compared to those in RAO. Most patients had hypertension(41.2% RAO and 55% RVO) and hyperlipidemia (35.5% RAO and 81.8% RVO). In all, 4 women were using oral contraceptives, 2 were pregnant or postpartum. Follow-up data was available for 28 patients (13 RAO, 15 RVO). Nineteen were treated with aspirin, four with warfarin, and one with low molecular weight heparin. Eight patients reported improvement in vision at time of follow-up (5 RAO, 3 RVO). Multiple risk factors are associated with RVO and RAO, and a complete assessment should include thrombophilia and cardiovascular studies.

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

OBJECTIVES

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

DESIGN

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

SETTING

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

PARTICIPANTS

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

Retinal vein occlusion: an approach to diagnosis, systemic risk factors and management

Retinal vein occlusion (RVO) is the second most common retinal vascular disease after diabetic retinopathy and is a common cause of visual morbidity and blindness in the elderly. A large proportion of patients with RVO have a history of cardiovascular disease, hypertension, diabetes mellitus or open-angle glaucoma. Although RVO is sometimes associated with thrombophilias and coagulation abnormalities, the role of coagulation factors in the development of RVO remains unclear. This review did not find strong evidence to support an extensive work-up for thrombophilic and coagulation diseases for the vast majority of patients. However, when tests for common cardiovascular risk factors for RVO are negative, evaluation for potential coagulation disorders may be indicated, particularly in young patients and in patients with bilateral RVO, a history of previous thromboses or a family history of thrombosis.

Central retinal vein thrombosis and hyperhomocysteinemia in a young patient with renal transplantation

A 28-year-old woman was admitted with a sudden loss of vision in the right eye. She underwent renal transplantation in June 1999 for chronic renal failure secondary to amyloidosis. Upon ophthalmologic examination, the patient was diagnosed with central retinal vein occlusion. Physical and laboratory examinations failed to disclose any remarkable pathology except for high homocysteine levels. Hyperhomocysteinemia has been reported as a potential risk factor requiring treatment and a significant association has been found between this condition and central retinal vein thrombosis.

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.

Branch retinal vein occlusion: pathogenesis, visual prognosis, and treatment modalities

In branch retinal vein occlusion (BRVO), abnormal arteriovenous crossing with vein compression, degenerative changes of the vessel wall and abnormal hematological factors constitute the primary mechanism of vessel occlusion. In general, BRVO has a good prognosis: 50-60% of eyes are reported to have a final visual acuity (VA) of 20/40 or better even without treatment. One important prognostic factor for final VA appears to be the initial VA. Grid laser photocoagulation is an established treatment for macular edema in a particular group of patients with BRVO, while promising results for this condition are shown by intravitreal application of steroids or new vascular endothelial growth factor inhibitors. Vitrectomy with or without arteriovenous sheathotomy combined with removal of the internal limiting membrane may improve vision in eyes with macular edema which are unresponsive to or ineligible for laser treatment.

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.

Cardiovascular and thrombophilic risk factors in patients with retinal artery occlusion

This article evaluates the prevalence of cardiovascular and thrombophilic risk factors in patients with retinal artery occlusion. Forty-one patients with a first episode of a retinal artery occlusion underwent complete ophthalmic examination, routine blood testing and specific laboratory tests for thrombophilia, such as fasting and postmethionine homocysteine, lipoprotein(a), plasminogen activator inhibitor-1, factor VIII, factor V Leiden, factor II G20210A polymorphism, lupus anticoagulant and anticardiolipin antibodies. The control population consisted of 100 healthy individuals comparable as regards age and sex. At univariate analysis, hypertension, smoking, dyslipidaemia (both high cholesterol and triglyceride levels), antiphospholipid antibodies, hyperhomocysteinaemia, elevated factor VIII and lipoprotein(a) levels were significantly associated with retinal artery occlusion; at multivariate analysis, adjusted for age, sex, traditional and thrombophilic risk factors, smoking, hypercholesterolaemia, elevated homocysteine and lipoprotein(a) levels confirmed their independent role as risk factors for retinal artery occlusion. In conclusion, the results of the present pilot study demonstrate that the prevalence of hypercholesterolaemia and smoking and the 'thrombophilic burden' are increased in patients with retinal artery occlusion. Our findings may have implications for the management of these patients, suggesting the need for an intensive and tailored secondary prevention and new therapeutic approaches.

Amaurosis fugax caused by heritable thrombophilia-hypofibrinolysis in cases without carotid atherosclerosis: thromboprophylaxis prevents subsequent transient monocular partial blindness

Nineteen patients (age 60 +/- 14) with amaurosis fugax associated with heritable thrombophilia-hypofibrinolysis without ipsilateral atherosclerotic carotid plaque or other causes of amaurosis fugax were studied. Our hypothesis was that case-specific thromboprophylaxis would prevent subsequent amaurosis fugax episodes. Prospective treatment data were available for 13 cases. Thrombophilic disorders included high Factors VIII and XI, G20210A prothrombin heterozygosity, low proteins C and S, MTHFR mutations, and the PL A1/A2 mutation. Hypofibrinolytic disorders included plasminogen activator inhibitor-1 4G4G, and high lipoprotein (a). Treatments included Coumadin; Lovenox, folic acid-vitamin B6-vitamin B12, discontinuation of estrogens-selective estrogen receptor modulators, Glucophage, and aspirin, as appropriate. Usually within 1 month on therapy, patients became asymptomatic and have remained asymptomatic for > or = 1 year on therapy, without adverse treatment side effects. When amaurosis fugax occurs without carotid artery atherosclerosis or other known causes, thrombophilia or hypofibrinolysis, or both are nearly universal, safely treatable, reversible pathoetiologies.

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

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

Dysfonction visuelle et occlusion artérielle : association à la mutation Leiden du facteur V ?

INTRODUCTION

The Leiden mutation of the factor V gene and the subsequent resistance of factor V to inactivation by activated protein C are associated with a procoagulant state, especially in the venous bed. However, its association with arterial thrombotic disease remains unclear.

OBSERVATIONS

We report four patients with visual field defects secondary to arterial occlusions and in whom we found a factor V Leiden mutation. These patients, three females and one male, aged 32-58 years, presented with various visual field defects: bilateral arciform scotomas due to multiple infarcts of the nerve fiber layer (one case), superior defect due to anterior ischemic optic neuropathy (one case), homonymous hemianopia due to stroke (two cases). An abnormal resistance to activated protein C and a heterozygous state for factor V Leiden mutation were found in all four cases. The two patients who suffered from a stroke also showed elevated antiphospholipid antibodies (one case) and a patent foramen ovale (one case).

COMMENTS AND CONCLUSION

Conflicting reports on the effective role of factor V Leiden mutation in arterial thrombotic events are present in the literature. We report four cases of arterial occlusion in whom a thrombophilic predisposition was present with a heterozygous state for factor V Leiden mutation. In two cases, no other risk factor was found. We hypothesize that factor V Leiden mutation, even in a heterozygous state, might predispose to arterial occlusion in some patients.

Amaurosis fugax: associations with heritable thrombophilia

The aim of this study was to prospectively assess associations between amaurosis fugax, inherited thrombophilia, and acquired thrombophilia. Thrombophilia and hypofibrinolysis were studied in 11 cases (eight women, three men; all white) with amaurosis fugax, 57 +/- 17 years old, selected by the absence of abnormal brain magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), magnetic resonance venography (MRV), ipsilateral internal carotid artery plaque, atrial fibrillation, or cardiac thrombus. Cases were compared to 78 healthy adult white controls (53 +/- 18 years old) for serologic measures, and by polymerase chain reaction to 248 healthy white controls (78 adults, 170 children) for gene mutations. All 11 cases had one or more familial thrombophilic coagulation disorder including one heterozygous for the G1691A factor V Leiden mutation, two with low free protein S, four with high factor VIII, three with resistance to activated protein C, three homozygous for the C677T methylenetetrahydrofolate reductase (MTHFR) mutation, two compound C677T-A1298C MTHFR heterozygotes, and three with hypofibrinolytic 4G4G homozygosity for the PAI-1 gene. The case with factor VIII of 160% had two other thrombophilias (compound MTHFR C677T-A1298C heterozygosity, resistance to activated protein C), and hypofibrinolytic high Lp(a). Thrombophilic C677T MTHFR homozygosity or compound C677T-A1298C heterozygosity was present in five of 10 (50%) cases vs. 30 of 248 (12%) controls, Fisher's p (p(f)) = .005. Thrombophilic factor VIII was high in four of 10 (40%) cases vs. 0 of 38 controls, p(f) = .001. Thrombophilic hyperestrogenemia in five of the eight women (four exogenous estrogen, one pregnant) may have interacted with inherited thrombophilia-hypofibrinolysis, promoting thrombus formation. In cases selected by the absence of abnormal brain magnetic resonance imaging, significant ipsilateral internal carotid artery plaque, atrial fibrillation, or cardiac thrombus, we speculate that amaurosis fugax can be caused by reversible (by anticoagulation) retinal artery thrombi associated with heritable thrombophilia and/or hypofibrinolysis, often augmented by estrogen-driven acquired thrombophilia.

Role of thrombophilic gene polymorphisms in branch retinal vein occlusion

OBJECTIVE

Branch retinal vein occlusion (BRVO) is a common cause of severe visual loss. Numerous risk factors, including arterial hypertension, diabetes mellitus, and arteriosclerosis, have been identified. Gene polymorphisms affecting hemostasis may also play a role in the pathogenesis of BRVO. The present study was therefore done to determine the prevalence of genetic polymorphisms in factors implicated in hypercoagulability among patients with BRVO.

DESIGN

Retrospective case-control study.

PARTICIPANTS

The study cohort consisted of 294 patients with BRVO and 294 control subjects, matched for age and gender.

METHODS

Determination of genotypes was done by allele-specific digestion of polymerase chain reaction products, or by 5' exonuclease assay (TaqMan).

MAIN OUTCOME PARAMETERS

Genotypes of factor V R506Q (factor V Leiden), prothrombin 20210G>A, fibrinogen beta -455G> A, factor XII (FXII) 46C>T, and ITGA2 807C>T (platelet glycoprotein Ia [GPIa] 807C>T) and ITGB3 L59P (platelet GPIIIa PlA1/PlA2) polymorphisms.

RESULTS

Genotype distributions of the investigated gene polymorphisms did not differ significantly between patients and control subjects. In contrast, significantly increased prevalences of arterial hypertension and hypercholesterolemia were found among patients with BRVO. In a logistic regression analysis, the presence of arterial hypertension was associated with an odds ratio (OR) of 2.32 (95% confidence interval [CI], 1.62-3.32), whereas hypercholesterolemia yielded an OR of 2.54 (95% CI, 1.74-3.70) for BRVO.

CONCLUSION

Our data indicate that the prevalences of the investigated gene polymorphisms do not differ significantly in patients with BRVO and control subjects. This suggests that these polymorphisms are not major risk factors for BRVO.

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.

Role of factor V Leiden and prothrombin 20210A in patients with retinal artery occlusion

PURPOSE

Retinal artery occlusion is a common vision-threatening disease. Among other risk factors, coagulopathies leading to a hypercoagulable state have been associated with retinal artery occlusion. Numerous studies have shown that two genetic variants, factor V Leiden and prothrombin 20210A, cause a procoagulant state. However, their role in the pathogenesis of retinal artery occlusion is still unclear. The purpose of the present study was therefore to investigate a possible association between factor V Leiden, prothrombin 20210A, and retinal artery occlusion.

METHODS

In the present retrospective case-control study, we studied 136 patients with retinal artery occlusion and 136 age- and gender-matched control subjects. The presence of factor V Leiden and prothrombin 20210A alleles was determined by polymerase chain reaction.

RESULTS

The prevalence of heterozygosity for the prothrombin G20210A variant did not significantly differ between patients and controls (three patients vs two controls, P=0.65). Distribution of factor V Leiden genotypes revealed no significant difference among the two groups (heterozygosity: eight patients vs 11 controls, P=0.47). As for other risk factors, arterial hypertension, a history of stroke and myocardial infarction were significantly more frequent in patients than in controls.

CONCLUSION

Our data suggest that factor V Leiden and prothrombin 20210A do not play a major role in patients with retinal artery occlusion.

Influence of factor V Leiden on the development of neovascularisation secondary to central retinal vein occlusion

AIMS

To investigate if the presence of factor V Leiden has an influence on the prognosis in central retinal vein occlusion (CRVO).

METHODS

166 patients with CRVO were studied retrospectively. They were tested for factor V Leiden using DNA analysis. The presence of the mutation was studied in correlation with the development of neovascular complications 1 year after the thrombotic event.

RESULTS

56 of 166 patients (34%) developed neovascular complications after 1 year. In the patients who had the studied mutation 11 of 20 (55%) had developed neovascular complications after 1 year, compared to 45 of 146 patients (31%) in the group without factor V Leiden (p=0.04).

CONCLUSION

The presence of factor V Leiden seems to enhance the risk of developing neovascular complications in CRVO.