⚡ Key Takeaways
- Always rule out perforation first — check IOP, AC depth, iris, and lens
- High-velocity mechanisms (drilling, grinding, hammer/chisel) are high risk for perforation
- Use a 25-gauge needle on a syringe to lever the foreign body out from underneath
- Remove the rust ring with the needle or a corneal burr
- Always evert the eyelid to check for additional foreign bodies
Watch the Full Video
Before You Start: Rule Out Perforation
Before touching the foreign body, perform a thorough slit lamp exam:
- Check depth of the foreign body with a slit beam
- Look for low IOP, corneal striae, blood in the AC, iris holes, or cataract
- Ask about the mechanism of injury
High-Risk vs. Low-Risk Mechanisms
Low risk: "Something fell in my eye in the shower" or "I was working overhead without glasses." These usually result in a superficial foreign body.
High risk: Drilling, grinding metal, or using a hammer and chisel. These create high-velocity, hot projectiles that can perforate the cornea. Examine these patients extra carefully.
Step-by-Step Removal
1. Anaesthetize
Apply tetracaine or equivalent anaesthetic drops. Give enough drops that the patient is completely comfortable.
2. Position the Patient
If the patient isn't cooperating, use a lid speculum. Have them look in a direction that gives you the best access to the foreign body.
3. Set Up Your View
Use moderate magnification — high enough to see the foreign body clearly, but with enough overview to track the patient's eye movements. Illuminate with a slit slightly from the side, but not too narrow.
4. Remove with a Needle
Use a 25-gauge needle (22 to 30 gauge all work) on a 1-3ml syringe for better grip. Go under one edge of the foreign body and tilt it up — most foreign bodies pop out easily. If the foreign body sticks to the cornea and won't come off the needle, use a Q-tip to catch it.
⚠️ Never let the foreign body out of your sight — it can hide under the lid and you'll spend ages looking for it again.
5. Remove the Rust Ring
If the foreign body has been there for some time, there's usually a rust ring. Use the needle to lift out the main chunks, then use a corneal burr for any remaining rust. Don't be overly aggressive — a small amount of residual rust will often reabsorb.
6. Check for More
Always evert the eyelid and look for additional foreign bodies, especially if you saw vertical fluorescein staining — this suggests something under the upper lid is scratching the cornea with each blink.
Frequently Asked Questions
Do I need to remove the entire rust ring?
Remove what you can without being too aggressive. Small amounts of residual rust will often reabsorb over days. Over-aggressive burring creates a larger corneal defect than necessary.
What treatment after removal?
Prescribe prophylactic antibiotic drops (e.g., fluoroquinolone) and follow up in 1-2 days to check healing. A cycloplegic drop can help with pain if the defect is large.
When should I refer to a specialist?
Refer if: the foreign body is deep/full-thickness, there are signs of perforation, there's an intraocular foreign body (IOFB), or you're not comfortable with the removal.
Want to learn more emergency eye skills?
Check out the anterior chamber paracentesis guide or subscribe to the YouTube channel.