Thrombophilia as a Risk Factor for Central Retinal Vein Thrombosis.
Authors: Girtovitis Fotios I , Tsakiroglou Elisabet , Diamantidis Michael D. , Saouli Zoi , Kontoninas Zisis , Voulgaridou Virginia , Merakis Ilias , Kaiafa Georgia , Papadopoulos Sr. Athanasios 
Published: October 2019

Abstract
Abstract 5054

Introduction
An increased risk of central retinal vein occlusion in patients with hypertension, hypercholesterolemia and diabetes mellitus has been recently shown. However, controversial literature results have failed to establish an association between central retinal vein occlusion and thrombophilic abnormalities.

Aim
To investigate thrombophilic factors in patients with central retinal vein thrombosis.

Material and Methods
20 patients with a median age of 48±13 yrs [7 males (median age 53,2±8,4 yrs) and 13 females (median age 48,1±17,7 yrs)], who presented in the Hemostasis Unit of the First Propedeutic Department of Internal Medicine of AHEPA hospital during the last two years, were studied. All the patients suffered from central retinal vein thrombosis, which was diagnosed by fluorescein angiography. Detailed evaluation of the coagulation mechanism included examination of fibrinogen, d-dimers, thrombin time, reptilase time, protein C, protein S, antithrombin III, activated protein C resistance, factor V-Leiden and prothrombin G20210A mutation, homocystein, II, V, VII, VIII, IX, X, XI and XII coagulation factors, anti-cardiolipin antibodies, lupus anticoagulants and anti-β2 glycoprotein I. Moreover, factors of increased cardiovascular risk (obesity, hypertension, diabetes, smoking, hyperlipidemia) were studied.

Results
3 male and 4 female patients suffered from antiphospholipid syndrome (APS) (5 had primary APS, 1 female had secondary APS due to systemic lupus erythematosus, while another female was diagnosed with both APS and thrombophilia Leiden). 5 patients (4 female καı 1 male) were heterozygotes for factor V-Leiden mutation. From these 5 patients, 2 were obese and had hypertension, 1 female had been receiving contraceptives, 1 other female had additionally increased levels of factor VIII (240%), whereas the fourth female suffered from additional protein S deficiency (41%). Interestingly, 4 female patients (4/20, 20%) were found to be double heterozygotes (factor V-Leiden and prothrombin mutation). In 3 females (1 of whom had a history of pulmonary embolism), the whole laboratory investigation for thrombophilic factors was negative. Increased homocysteine levels, reduced levels of natural coagulation inhibitors, along with local ophthalmic factors (i.e. glaucoma) justifying thrombosis, were traced in none of the patients.

Conclusions
1) APS and thrombophilia Leiden are the most important causal factors for ophthalmic vein thrombosis. However, thrombophilia Leiden alone, does not seem responsible for causing thrombosis, since other thrombophilic factors co-existed in 8/9 patients 2) Hyperhomocysteinemia –in contrast with the results of other studies- does not appear to be a risk factor 3) The high percentage of double heterozygotes (20%) is noteworthy in the aforementioned patients.

Disclosures
No relevant conflicts of interest to declare.