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.
Central retinal artery occlusion occurs when the central retinal artery becomes blocked, usually due to an embolus. It causes sudden, painless, unilateral, and usually severe vision loss.Diagnosis is by history and characteristic retinal findings on funduscopy.entral retinal artery occlusion occurs when the central retinal artery becomes blocked, usually due to an embolus. It causes sudden, painless, unilateral, and usually severe vision loss.