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 photo- 
   phobia, 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., erythro- 
   mycin, 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 epi- 
thelial 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

 ----------------------------------------------------
 from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
 Longwood Information LLC 4822 Quebec St NW Wash DC
 1.202.237.0971 fax 1.202.244.8393 electra@clark.net
 ----------------------------------------------------