A corneal abrasion usually results from a foreign body, such as a cinder or a piece of dust, dirt, or grit, which becomes embedded under the eyelid. Even if the foreign body is washed out by tears, it may still injure the cornea.
A small piece of metal that gets in the eyes of workers who don’t wear protective glasses quickly forms an abrasion and then forms a rust ring on the cornea. Abrasions also commonly occur in the eyes of people who fall asleep wearing hard contact lenses. A corneal scratch produced by a fingernail, a piece of paper, or another organic substance may cause a persistent lesion. The epithelium doesn’t always heal properly, and a recurrent corneal erosion may develop, with delayed effects more severe than those of the original injury.
Signs and symptoms
Typically, corneal abrasions produce redness, increased tearing, a sensation of “something in the eye” and, because the cornea is richly endowed with nerve endings from the trigeminal nerve (cranial nerve V), pain disproportionate to the size of the injury. A corneal abrasion may affect