2.06 Corneal Abrasion

agk’s Library of Common Simple Emergencies

Presentation

The patient may complain of eye pain or a foreign body sensation after being poked in the eye with a finger or twig. The patient may have abraded the cornea inserting or removing contact lenses. Removal of a corneal foreign body produces some corneal abrasion, but corneal abrasion can even occur without identifiable trauma. There is often excessive tearing and photophobia. Often the patient cannot open his eye for the exam. Abrasions are occasionally visible on sidelighting the cornea. Conjunctival inflammation can range from nothing to severe conjunctivitis with accompanying iritis.

What to do:

• Instill topical anesthetic drops (to permit exam).
• Perform a complete eye exam (visual acuity, funduscopy, anterior chamber bright light, conjunctival sacs for foreign body).
• Perform the fluorescein exam by wetting a paper strip impregnated with dry orange fluorescein dye and touching this strip into the tear pool inside the lower conjunctival sac. After the patient blinks, darken the room and examine the patient’s eye under cobalt blue or ultraviolet light (the red-free light on the ophthalmoscope does not work). Areas of denuded or devitalized corneal epithelium will fluoresce green.
• If a foreign body is present, remove it and irrigate the eye.
• If iritis is present (evidenced by photophobia, an irregular pupil or meiosis, and a limbic blush in addition to conjunctival injection) consult the ophthalmologic followup physician about starting the patient on topical mydriatics and steroids (e.g., cyclopentolate or homatropine and prednisolone).
• Instill antibiotic ointment (e.g., erythromycin, tobramycin) in the lower sac. A small, superficial, non-painful abrasion may be left uncovered.
• For large, deep, and painful abrasions, patch the eye with enough pressure to keep the lid closed by folding one eyepatch double to rest against the lid, covering it with a second unfolded eyepatch, and taping both tightly with several strips of 1" tape running from the cheek to mid forehead.
• Prescribe analgesics (e.g., oxycocone, ibuprofen, naproxen), and give the first dose.
• Warn the patient the pain will return when the local anesthetic wears off.
• Make an appointment for ophthalmologic followup to reevaluate the abrasion the next day.

What not to do:

• Do not be stingy with pain medication. Patching alone will not eliminate the pain.
• Do not give patient any topical anesthetic for continued instillation.
• Do not patch a patient with a bacterial conjunctivitis or ulcer.
• Do not tape an eye patch up and down or across the nose.

Discussion

Corneal abrasions are a loss of the superficial epithelium of the cornea. They are generally a painful injury, because of the extensive innervation. Healing is usually complete in one to two days unless there is extensive epithelial loss of underlying ocular disease (e.g., diabetes). Scarring will occur onlly if the injury is deep enough to penetrate into the collagenous layer.

Fluorescein binds to corneal stroma and devitalized epithelium, but not to intact corneal epithelium. Collections of fluorescein elsewhere, in conjunctival irregularities and in the tear film, are not pathological.

Continuous instillation of topical anesthetic drops can impair healing, inhibit protective reflexes, permit further eye injury, and even cause sloughing of the corneal epithelium. If the abrasion is small or the patient is significantly distressed by patching, topical antibiotic drops or ointment can be used alone. The patch does not significantly improve healing or pain relief.

With small superficial abrasions the patient does not require follow up if he is completely asymptomatic in 12-24 hours. With larger abrasions or with any persistant discomfort, ophthalmologic follow up is necessary because of the risk of corneal infection or ulceration.

Hard contact lenses can abrade the cornea, but can also cause diffuse ischemic damage when worn for more,.than 12 hours at a time, by depriving the avascular corneal epithelium of oxygen and nutrients in the tear layer.

References:

• Kirkpatrick J: No eye pad for corneal abrasions. Eye 1993;7:468

Illustration

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