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.
Probably unrelated: Retinal holes are usually causes by physical problems within the eye, such as the vitreous gel pulling on the retina and causing a tear. Most cases of retinal holes are of unknown cause and are not usually associated with medical conditions. Symptoms of nausea, headache and sin ...Read more.