F2 and protein S deficiency: Several systemic conditions have been associated with retinal vascular occlusions, including hyperviscosity and hypercoagulability conditions: specifically, protein C and protein S deficiency, prothrombin gene mutation, anti-thrombin abnormalities, anti-phospholipid syndrome (anti-cardiolipin and lupus anti-coagulant), factor V Leiden deficiency, and hyperhomocysteinemia28–31.