Activated protein C resistance in patients with central retinal vein occlusion in comparison to patients with a history of deep-vein thrombosis and ahealthy control group

Background: The recently described "APC resistance" caused by a mutant form of factor V (factor V Leiden) is the most frequent cause of hereditary thr ombosis. This study was carried out to investigate the association between activated protein C resistance and central retinal vein occlusion (CRVO). W e evaluated the prevalence of APC resistance in patients with CRVO, patient s with a history of deep-vein thrombosis, and a healthy control group. Patients and methods: We examined 107 patients with CRVO, 112 patients with deep-vein thrombosis and 70 healthy individuals. The test performed was a modified APC-resistance assay using factor V-deficient plasma. Results: We identified APC resistance in 5.6 % of patients with CRVO and in 5.7 % of the control group. All carriers were heterozygous. In the deep-ve in thrombosis group 23.2 % tested positive for APC resistance. Four patient s were homozygous and 22 were heterozygous carriers. Conclusion: These results indicate that APC resistance has no major role in the pathogenesis of CRVO. Routine testing for the presence of factor V Lei den mutant in CRVO is not necessary.