Corneal disease is a serious condition that can cause clouding, distortion, scarring and eventually blindness. There are many types of corneal disease. The three major types are keratoconus, Fuchs' endothelial dystrophy and bullous keratopathy. Symptoms of corneal disease. With keratoconus, as the cornea protrudes or steepens, vision becomes increasingly blurred and contact lens wear, which is often an early treatment for the disease, becomes difficult.