Corneal Abrasion

Corneal abrasion is a medical condition involving the loss of the surface outer (epithelial) layer of the eye's cornea.

Corneal abrasions are generally a result of trauma to the surface of the eye. Common causes include jabbing a finger into an eye, walking into a tree branch, getting grit in the eye and then rubbing the eye or being hit with a piece of projectile metal. A foreign body in the eye may also cause a scratch if the eye is rubbed. Injuries can also be incurred by "hard" contact lenses that have been left in too long. Damage may result when the lenses are removed, rather than when the lens is still in contact with the eye. In addition, if the cornea becomes excessively dry, it may become more brittle and easily damaged by movement across the surface.

Symptoms of corneal abrasion include pain, light sensitivity, a foreign-body sensation, excessive squinting, and a reflex production of tears. Signs include epithelial defects and swelling, and often conjunctival injection, swollen eyelids, large pupils and a mild anterior-chamber reaction. The vision may be blurred, both from any swelling of the cornea and the excess tears. Crusty build up from excess tears may also be present.

Although corneal abrasions may be seen with hand held lights, slit lamps provide higher magnification which allow for a much more thorough evaluation. To aid in viewing, a fluorescein (orange dye and anesthetic drop) stain that fills in the corneal defect and glows with a cobalt blue-light is generally instilled first.

A careful search should be made for any foreign body, in particular looking under the eyelids. Injury following use of hammers or power-tools should always raise the possibility of a penetrating foreign body into the eye, for which urgent ophthalmology opinion should be sought.

Although small abrasions may require no specific treatment, larger abrasions are typically treated for a few days with a topical anti-biotic to prevent infection and sometimes a topical cycloplegic (dilating drop)to reduce pain and improve comfort.

A single large study by John W. King, et al, showed that only 0.7% of corneal abrasions actually become infected without antibiotic drops, questioning the necessity of such practice. The cycloplegic may also reduce a secondary inflammation of the iris known as an iritis.

It is often believed that eye pads used in "pressure patching" may improve comfort and promote healing by preventing repeated eyelid blinking that may cause further physical disruption to the cornea.

Due to the introduction of newer contact lens materials, mainly silicone hydrogels, pressure patch treatment is being phased out and replaced by "bandage contact lenses". These newer materials provide much more oxygen to the cornea and can be fitted tightly (providing minimal movement) with a low risk of complications. These lenses greatly decrease the patients pain and allow the patient to administer drops.

For recurrent corneal erosions, laser surgery may be indicated.

Topical anesthetics are not to be used for continued pain control as they can reduce healing and cause secondary keratitis.