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.
In proliferative retinopathy, new, structurally unstable blood vessels grow on the surface of the retina. These unstable blood vessels cause frequent minor bleeding. The bleeding causes local irritation and scarring.Proliferative retinopathy can cause retinal detachment. This is a separation of the layers of the retina. It is one of the most serious consequences of proliferative retinopathy.The vitreous is the clear gel between the lens and the retina.