The cornea is the transparent, dome-shaped window that covers the front of the eye. A nick, scratch or scrape of the cornea is called a corneal abrasion. Corneal abrasions are one of the most common forms of eye injury. In some cases, they are caused by the direct impact of a sharp object, such as a pencil, staple, nail or sewing pin. They also can be caused by small, airborne particles, such as dust, sand or flying debris from soldering, woodworking or weed trimming.