2.05 Corneal Foreign Body
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agk's Library of Common Simple Emergencies

Presentation
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The eye has been struck by a falling or blowing 
particle, often a fleck of rust while working 
under a car, or a loose foreign body has become 
embedded by rubbing, thereby producing intense 
pain. Moderate to high-velocity foreign bodies 
(fragments chipped off a chisel by a hammer or 
spray from a grinding wheel) can be super- 
ficially embedded or lodged deep in the 
vitreous. Superficial foreign bodies may be 
visible during simple sidelighting of the 
cornea or by slit lamp examination. Deep 
foreign bodies may be visible only as moving 
shadows on funduscopy, with a trivial-appearing 
or invisible puncture in the sclera.

What to do:
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- Instill topical anesthetic drops.
- Perform visual acuity and funduscopy (look 
   for shadows), bright light anterior chamber 
   (slit lamp is best), and check pupillary 
   reflexes (for iritis) and conjunctivae (for 
   loose foreign bodies).
- If there is any suspicion of a penetrating 
   intraocular foreign body, then get special 
   orbital x rays or CT scans to locate it or 
   rule it out.
- A barely embedded foreign body might be 
   touched out with a moistened swab as shown 
   in the section on the conjunctival foreign 
   body, but if firmly embedded, it will have 
   to be scraped off (under magnification) with 
   an ophthalmic spud or an 18 gauge needle. 
   Give the patient an object to fixate upon to 
   keep his eye still, brace your hand on his 
   forehead or cheek, and approach the eye 
   tangentially so no sudden motion can cause a 
   perforation of the anterior chamber. Removal 
   of the foreign body leaves a defect which is 
   treated as a corneal abrasion. If a rust 
   ring is present, it will appear that a 
   foreign body remains adherent to the cornea. 
   Use the needle to continue to scrape away 
   this rust-impregnated corneal epithelium. A 
   corneal burr is preferable for this task, if 
   available.
- If unclear, perform a fluorescein exam to 
   document the extent of the corneal defect.
- Finish with further irrigation for possible 
   fragments, instill drops of a mydriatic like 
   homatropine, antibiotic ointment, eye patch, 
   and analgesic medication (Percocet, 
   ibuprofen, etc.), the first dose given 
   before leaving the ED.
- Make an appointment for ophthalmologic 
   followup the next day, to evaluate healing 
   and any residual foreign bodies.

What not to do:
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- Do not overlook a foreign body deep inside 
   the globe: the delayed inflammatory response 
   can lead to blindness.
- Do not leave an iron foreign body in place 
   without arranging early ophthalmic followup.
- Do not be stingy wuth pain medication. Large 
   corneal abrasions following foreign body 
   removal can be quite painful despite 
   patching the eye.
- Do not forget to thell the patient, if 
   homatropine was instilled, that he will have 
   blurred near vision and an enlarged pupil 
   for 12-24 hours.

Discussion
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Decide beforehand how much time you will spend 
(and how much trauma you will inflict on the 
cornea) before giving up on removing a corneal 
foreign body and calling your ophthalmologic 
consultant. Some emergency physicians recommend 
using a small needle for scraping, to minimize 
the possibility of a corneal perforation, but 
with a tangential approach the larger needle is 
less likely to cause harm.

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 from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
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