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Corneal Abrasion

Often caused by a foreign body, a corneal abrasion is a scratch on the surface epithelium of the cornea. An abrasion or foreign body in the eye is the most common eye injury. With treatment, the prognosis is usually good.

Causes

A corneal abrasion usually results from a foreign body, such as a cinder or a piece of dust, dirt, or grit, that 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. Such 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

Symptoms of corneal abrasion include pain, photophobia , a foreign-body sensation, and a reflex production of tears . Signs include epithelial defects and edema , and often conjunctival injection, swollen eyelids, and a mild anterior-chamber reaction. The vision may be blurred, both from any swelling of the cornea and the excess tears.

Diagnosis

Ophthalmologists and optometrists, who treat eye disorders, are well qualified to diagnose corneal abrasions. The doctor will check the patient's vision (visual acuity) in both eyes with an eye chart. A patient history will also be taken, which may help to determine the cause of the abrasion. A slit lamp, which is basically a microscope and light source, will allow the doctor to see the abrasion. Fluorescein, a yellow dye, may be placed into the eye to determine the extent of the abrasion. The fluorescein will temporarily stain the affected area.

Treatment

The first steps in treatment include examining the eye and checking visual acuity. If the foreign object is visible, the eye can be irrigated with normal saline solution.

Removal of a deeply embedded foreign body is done with a foreign-body spud, using a topical anesthetic. A rust ring on the cornea must be removed at the slit-lamp examination with an ophthalmic burr, after applying a topical anesthetic. When only partial removal is possible, reepithelialization lifts the ring again to the surface and allows complete removal the next day.

Treatment also includes instillation of a cycloplegic eyedrop and broadspectrum antibiotic eye drops in the affected eye every 3 to 4 hours.

CLINICAL TIP A pressure patch may be applied in some cases, but it's never used if the abrasion was caused by contact lens use.

Prevention

Take the following steps to help prevent corneal abrasions:

• Wear protective eye goggles when you're around machinery that causes particles of wood, metal or other materials to fly into the air (such as a chainsaw or a sandblaster).
• Cut infants' and young children's fingernails short.
• Trim low-hanging tree branches.
• Use care when putting in contact lenses.