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Corneal and subtarsal foreign bodies

  • Emergency

A speck in the eye is found with fluorescein and lid eversion. Most come off with irrigation or a swab; deep, central or high-speed ones go to ophthalmology.

Updated

See it in 3D: Cornea · Eyelids

What it is

Corneal and conjunctival foreign bodies (metal, wood, dust, insects) are among the commonest eye injuries, especially at work. They cause a gritty pain, tearing and light sensitivity. Most are superficial and can be removed in the emergency room after a topical anaesthetic. The key is to not miss a particle under the upper lid, a penetrating injury or a retained intraocular fragment.

How to recognise it

  • High-speed mechanism (hammering, grinding, drilling): possible intraocular foreign body.
  • Vertical scratches on the cornea: a particle under the upper lid.
  • A positive Seidel test, a peaked pupil or a shallow anterior chamber: penetrating injury.
  • A white infiltrate around the particle: infection.
  • Plant material: risk of fungal keratitis.

What to do at once

  1. Ask the mechanism and measure visual acuity.
  2. Instil a topical anaesthetic and fluorescein, and look with a bright light and magnification.
  3. Evert the upper lid and sweep the fornix with a moist swab.
  4. Try irrigation first, then a moist cotton swab for a superficial particle.
  5. Embedded particles are lifted at the slit lamp with a fine needle by a trained clinician; a rust ring is removed by ophthalmology.
  6. Give a topical antibiotic and analgesia; patching is not needed.
  7. Review within 24 to 48 hours.

Mistakes that cost sight

  • Topical anaesthetic drops are for the examination only: repeated use at home damages the cornea and hides complications.
  • A metal fragment leaves a rust ring within hours, which slows healing if left.
  • X-ray or CT of the orbits is needed whenever an intraocular fragment is possible.

Next step / Initial management

  • Superficial particle removed: topical antibiotic, oral analgesia and review in 24 to 48 hours.
  • Refer to ophthalmology the same day: deep or central particles, a large rust ring, failure to remove, a corneal infiltrate, plant matter or suspected penetration.
  • Suspected intraocular foreign body: shield the eye, CT of the orbits and emergency referral.
  • Advise eye protection at work.

Test yourself

Think of the answer, then tap the question to see it.

What do vertical linear scratches on the cornea suggest?

A foreign body trapped under the upper lid; the lid must be everted.

Which history makes an intraocular foreign body likely?

Hammering metal on metal, grinding or drilling: small high-speed fragments can enter the eye.

Why are topical anaesthetic drops not given to take home?

Repeated use delays healing, can cause corneal ulceration and masks worsening symptoms.

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Connections

See it in 3D2

The structures of Durgical's 3D anatomy where it is found.

In Pharmacology3

← All of ophthalmology

Educational content; not a clinical guideline and no substitute for assessment by a health professional. For sudden visual loss, severe eye pain, a chemical burn or an eye injury, go to an emergency department at once.

Sources: Corneal Foreign Body (StatPearls Publishing (NCBI Bookshelf), 2025); Corneal Foreign Body Removal (StatPearls Publishing (NCBI Bookshelf), 2023); Corneal Abrasion (StatPearls Publishing (NCBI Bookshelf), 2024).

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Representative model, for educational purposes only.