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.
The branches of the central artery of the retina are endarteries, so that an occlusion causes loss of vision in the corresponding part of the visual field. The fundus oculi is the posterior part of the interior of the eye as seen on ophthalmoscopy (fig. 46-9).