A foreign object that hits the cornea can cause an injury. The cornea is a transparent covering of the center of the eye. It allows light to penetrate into the eye, where it strikes the retina and is eventually interpreted by the brain as vision. The cornea is soft and the foreign object may become lodged in it. If the foreign object is metal a rust ring can develop around the injury as well. If the foreign body and the rust ring are not removed a corneal scar can occur resulting in permanent vision loss.