High Prevalence of Hyperhomocysteine in Retinal Vein Occlusion.
Authors: Pollio Berardino , Delios Grazia , Ladetto Marco , Tucciarone Marco , Di Bassiano Francesco , D’Ardia Stefano , Schinco Piercarla , Girotto Mauro 
Published: April 2020

Abstract
Retinal vein occlusion (RVO) is a common cause of blindness. Despite its clinical relevance, the role of inherited thrombophilia in RVO is controversial (Janssen MC et al., Thrombosis and Haemostasis2005; 93).
Although many authors consider more important the role of anatomical conditions of lamina cribrosa rather than hypercoagulability in pathogenesis of this disease, the use of antithrombotic drugs for treatment of RVO is widespread (Prisco D et al., Pathophysiology of Haemostasis and Thrombosis2002;32).
To evaluate the most important thrombotic risk factors, we collected the data of 80 consecutive patients referred to our Centers for a RVO confirmed by fluoroangiography. Our cohort includes 39 women and 41 men with median age of 66 years; we observed 42 central retinal vein occlusions (CRVO) and 38 branch retinal vein occlusions (BRVO) from March 2002 to July 2005. We collected the following data about cardiovascular risk factors: the prevalence of arterial hypertension was 47,5% (38/80), dyslipidemia 22.5% (18/80), obesity 7.5% (6/80), diabetes mellitus 10% (8/80).
Forty-four patients (55%) demonstrated one or more atherosclerotic risk factors. The prevalence of acquired conditions did not show any statistical difference between CRVO and BRVO patients.
Moreover we tested fasting homocysteine in 60 patients detecting hyperhomocysteine (defined as a value of homocysteine above 95° percentile of laboratory control group) in 19 cases (31%).
Only one patient showed Lupus Anticoagulant and anticardiolipin antibody positivity.
Moreover we registered a CRVO during tamoxifen treatment and another one during hormonal therapy.
When we considered venous thrombophilia (hormonal therapy, neoplasia, immobilization, surgery, hyperhomocysteine, LAC) we found 25 patients (31.3%) having one or more acquired thrombotic risk factors.
Besides, all patients were tested for: antithrombin III, protein C and protein S, activated protein C resistance, factor V Leiden and prothrombin G20210A.
We found the presence of genetic trombophilia in 14 patients (17,5%): nine patients had protein S deficit; five had prothrombin gene mutation and one patient had factor V Leiden and one had factor XII deficit (two patients had multiple defects). Results of our survey confirme that acquired risk factors have a more relevant role that genetic thrombophilia in OVR. To draw a conclusion, extensive screening of genetic thrombophilia is not cost-effective in RVO but detection of plasmatic homocysteine concentration can be useful because high frequency of hyperhomocysteine and the possibility of treatment with vitamin B12 and folic acid.
Finally we are surprised to see high frequency of protein S deficit in our cohort.
Clinical features of 80 retinal vein thrombosis Number of patients: 80 Male/female: 41/39 Median age: 66 Date of recruitment March 2002 -July 2005 Branch retinal vein occlusion 38/80 Central retinal vein occlusion 42/80 Thrombotic risk factors in RVO Hyperhomocysteine 19/60 (31.6%) Genetic thrombophilia 14/80 (17.5%) Protein S deficit 9/80 (11.25%) Prothrombin gene mutation 5/80 (6.3%) Acquired venous risk factors 25/80 (31.3%) Atherosclerotic risk factors 44/80 (55%)