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.
1 Acute PVD: Vitreous hemorrhage in the setting of acute PVD is associated with a retinal tear or break in 70-95% of cases and should invoke an exhaustive search for retinal breaks.  Terson syndrome: Terson syndrome is a rare cause of vitreous hemorrhage associated with subarachnoid hemorrhage.