The cornea is the dome-shaped clear covering at the center of your eyes. It protects your eyes, and its curvature is also responsible for many aspects of our vision. It is a highly complex series of cells and proteins, and unlike most of the tissues of the body, it has no veins or blood vessels of any kind to help nourish and maintain it, because the blood vessels would interfere with our vision. This makes it vulnerable to outside infections and diseases, of which there are many.