Recurrent multiple-branch retinal arteriolar occlusions in a patient with protein C deficiency.

A 34-year-old woman is presented who has recurrent, multiple, retinal arteriolar occlusions associated with a deficiency in protein C, a vitamin K-dependent anticoagulant. Protein C is a naturally occurring anticoagulant and if there is a deficiency, it can lead to episodes of thrombosis; the deficiency can be acquired or congenital. This is the first documented case of retinal arteriolar occlusion associated with a congenital deficiency of this protein. The mechanism for arteriolar occlusion in this patient is discussed, and whilst the role of protein C deficiency remains presumptive, it is strongly implicated.