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.
Retinal vein occlusion is blockage of one of your retinal veins, which are blood vessels that carry deoxygenated blood back to your heart. Retinal vein occlusion is also divided into two types: Central retinal vein occlusion (CRVO) is a blockage in the main vein of your retina, which is called the central retinal vein.