A corneal abrasion is a scratch of the outermost layer of the eye. This is usually due to some sort of trauma or injury caused by fingernails, tools, pieces of paper, branches, etc. Foreign bodies such as glass, wood, or plastic can also cause corneal abrasions. It is also possible for a corneal abrasion to be caused by a contact lens which is poorly fitted or cleaned. Diagnosis can be done quickly using a slitlamp.