Corneal foreign bodies

Introduction

• Corneal foreign body is a common ED presentation.
• Most can be removed under local anaesthesia using a sterile needle or dental burr.
• Always consider the mechanism of injury — high-velocity trauma may cause penetrating injury.

Pathology

• Any material can lodge in the cornea.
• Most common ED presentation: high-velocity metal fragment.
• Grinder injuries rarely penetrate.
• Hammer-on-metal or high-speed drill injuries → higher risk of penetrating injury and intraocular foreign body.

Clinical Assessment

History

1. Intense eye pain, watering, and foreign body sensation
2. Symptoms may also occur with a subtarsal FB (under eyelid)
3. Mechanism of injury: important for velocity and penetration risk

Examination

1. Check visual acuity
2. Inspection
   • FB often visible; use slit lamp if not obvious
   • Assess cornea, anterior chamber, iris, pupil, and lens for signs of penetration
3. Evert the upper lid — look for subtarsal FBs
4. Establish site of FB
   • Central cornea (within 3 mm of pupil): scarring risk → consider ophthalmology referral
5. If no FB found:
   • Consider abrasion/ulcer (use fluorescein + cobalt blue light)

Investigations

• If penetrating injury suspected → plain radiographs or CT to detect intraocular FB

Management

• Topical anaesthetic (e.g. oxybuprocaine, amethocaine)
• Removal technique:
  • Use 19–30G needle on 2–3 mL syringe
  • Approach obliquely, bevel edge to scrape FB away from globe
  • Remove associated rust rings with:
    • Sterile needle
    • Dental burr
    • Algebrush device
  • Subtarsal FBs → remove with cotton bud

• Eye pad optional:
  • May improve comfort for 1–2 hours only
• Topical antibiotics:
  • Drops 4x daily for 3–4 days
  • Ointment at night if needed
• Contact lenses:
  • Stop wearing until healed + 1 week

Disposition

• GP review in 48 hours
• Ophthalmology referral if:
  • All FBs cannot be removed
  • Central corneal involvement
  • Suspicion of penetration

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Appendix 1

Appendix 2

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References

FOAMed

• Nickson C. Ophthalmology Befuddler. Clinical Cases. LITFL

Publications

• The Eye Emergency Manual, NSW Department of Health, 2nd ed. 2009