In a retrospective study investigating the risk factors for thrombophilia in patients with RAO and retinal vein occlusion (RVO), it was found that approximately 53% of RAO patients had at least one thrombophilia factor, including antiphospholipid antibodies, prothrombin gene mutation, elevated homocysteine, protein C and protein S deficiencies.35 This evidence concerns the gene PROS1 and thrombophilia.