Corneal Foreign Bodies
· Corneal foreign bodies account for approximately 35% of all eye injuries seen in the ED
· Corneal foreign bodies are usually superficial and benign, but penetration into the globe can cause loss of vision
· Foreign bodies are generally small pieces of metal, wood, or plastic
· The presence of a corneal foreign body causes an inflammatory reaction, dilating blood vessels of the conjunctiva and causing edema of the lids, conjunctiva, and cornea
· If present for >24 hours, WBCs may migrate into the cornea and anterior chamber as a sign of iritis
· Occasionally, the foreign body may be visible with the naked eye
· Evert the lid to identify and remove other foreign bodies
· When a metallic foreign body is present for more than a few hours, a rust ring develops around the metal
· The presence of a gross hyphema or a microhyphema evident in the anterior chamber on slit lamp examination suggests globe perforation
· If the foreign body has penetrated the cornea, the tract of the projectile may be seen. The Seidel test may be positive with penetration of the globe
· Contact lens use should be avoided until the defect is fully healed or feels normal for at least 1 week.
Foreign Body Removal
· Anesthetize the cornea with a local anesthetic
· Anesthetizing both eyes can be helpful, because that can eliminate reflex blinking during attempts at foreign body removal
· Irrigate with normal saline first, as a very superficial foreign body may be irrigated off the cornea
· Next, try to dislodge the foreign body with a moistened cotton applicator (Q-tip)
· If the foreign body is tightly adherent to or embedded in the cornea, inspect the cornea using optic sectioning on the slit lamp to assess the depth of penetration
· Full-thickness corneal foreign bodies should be removed by an ophthalmologist
· For superficial foreign bodies, a 25-gauge needle (using needle bevel up) or a sterile foreign body spud (1 mm diameter) on an Alger brush (a low-speed, low-torque, battery-operated hand-held drill) can be used to remove the foreign body
· Using either the 25-gauge needle or the Alger brush, place the tip into the slit lamp beam using the naked eye
· Using the bevel-up edge of the tip of the 25-gauge needle, hook the edge of the foreign body and dislodge it. You may then lift it off the cornea using the previously moistened cotton applicator
· Alternatively, using the spinning tip of the Alger brush, the foreign body may be dislodged and removed with the cotton applicator as above.
· Administer tetanus toxoid as appropriate.
· Provide ophthalmology follow-up the NEXT DAY if the foreign body is in the central visual axis or if there is a residual rust ring.
· Otherwise, after complete removal of the foreign body, advise follow-up in 48 hours.
· After successful foreign body removal, discharge the patient with a prescription for topical antibiotics, cycloplegics, and oral analgesics.
Antibiotics
· Does Not Wear Contact Lens
o Erythromycin ointment qid x 3-5d OR
o Ciprofloxacin 0.3% ophthalmic solution 2 drops q6 hours OR
o Ofloxacin 0.3% solution 2 drops q6 hours
· Wears Contact Lens
o Antibiotics should cover pseudomonas and favor 3rd or 4th generation fluoroquinolones
o Moxifloxacin 0.5% solution 2 drops every 2 hours for 2 days THEN q6hrs for 5 days OR
o Tobramycin 0.3% solution 2 drops q6hrs for 5 days OR
o Gatifloxacin 0.5% solution 2 drops every 2 hours for 2 days THEN q6hrs for 5 days OR
o Gentamicin 0.3% solution 2 drops six times for 5 days
Rust Ring Removal
· Metallic foreign bodies can create rust rings that are toxic to the corneal tissue.
· If a rust ring is present, the spud or an ophthalmic burr can remove superficial rust, but rust often reaccumulates by the next day, requiring additional burring.
· It is therefore not necessary to remove a rust ring in the ED if the patient can be seen by an ophthalmologist the next day
· Once the metallic foreign body is removed, the rust ring area softens overnight and can be more easily removed in the office the next day
· The deeper the stromal involvement, the higher is the risk of corneal scarring, so if rust ring removal is done in the ED, only perform superficial burring
· No ED drill burring should take place if the rust ring is in the visual axis (pupil) owing to the risk of causing visually significant scarring
References
Tintinalli’s Emergency Medicine a Comprehensive Study Guide 8th Edition
https://litfl.com/something-in-my-eye-doc/
https://accessemergencymedicine.mhmedical.com/content.aspx?bookid=683§ionid=45343806