Webster Dictionary(0.00 / 0 votes)Rate this definition: Freebase(0.00 / 0 votes)Rate this definition: Crenulation or Crenulation cleavage is a texture formed in metamorphic rocks such as phyllite, schist and some gneiss by two or more stress directions resulting in superimposed foliations.
Retinal vein occlusions typically occur in older patients with a history of high blood pressure and atherosclerosis. Other causes of retinal vein occlusion include vasculitis, clotting disorders, and medications such as oral contraceptive pills.
The blood then leaves the retina via the vein. The central retinal vein is located very close to the eye nerve (optic nerve). What is Central Retinal Vein Occlusion? Central Retinal Vein Occlusion (CRVO) is caused by a blood clot in the vein that drains the blood from the retina of the eye. The artery brings continuous blood to the retina but the blood can not leave the retina because of the block in the vein.