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 artery occlusion. Retinal artery occlusion is a blockage in one of the small arteries that carry blood to the retina. The retina is a layer of tissue in the back of the eye that is able to sense light. Causes. Retinal arteries may become blocked when a blood clot or fat deposits get stuck in the arteries.
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.