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 vessel occlusion. A retinal vessel occlusion is a blockage in the blood vessels of your eye that can cause sight loss. There are two types of retinal blood vessels, arteries and veins, and either of these can be affected by an occlusion. This information describes these two different types of vessel occlusion and their affect on vision.