How to Remove a Metallic Foreign Body From the Cornea and Manage Follow-Up Care
Metallic corneal foreign bodies are common in eye care, especially after grinding, drilling, hammering, metal work, lawn work, or construction exposure. Even a tiny metal fragment can cause significant pain, tearing, photophobia, foreign body sensation, and corneal inflammation.
Prompt evaluation is important because iron-containing foreign bodies can begin forming a rust ring within hours of becoming embedded in the cornea. Rust can prolong inflammation, delay epithelial healing, and increase the risk of corneal scarring if not managed appropriately.
This article reviews a practical approach to evaluating, removing, treating, and following metallic corneal foreign bodies.
Initial Evaluation
Before removing a corneal foreign body, the clinician should perform a careful history and slit lamp examination.
Important history questions include:
What was the patient doing when the injury occurred?
Was the patient grinding, hammering, drilling, welding, or working with metal?
Was eye protection worn?
Did the object hit the eye at high speed?
When did the injury occur?
Has the patient tried to remove it?
Does the patient wear contact lenses?
Is there decreased vision, severe pain, discharge, or light sensitivity?
Is tetanus status up to date when clinically relevant?
High-velocity trauma is especially important. A patient who was hammering metal on metal, grinding without eye protection, or struck by a fast-moving fragment should be evaluated carefully for penetrating injury or intraocular foreign body.
Red Flags That Require Urgent Referral
Not every corneal foreign body should be removed in-office. Refer urgently to ophthalmology or emergency care if there is concern for:
Open globe injury
Positive Seidel test
Full-thickness corneal penetration
Deep stromal foreign body near Descemet membrane
Intraocular foreign body
Irregular or peaked pupil
Shallow anterior chamber
Hyphema
Significant anterior chamber reaction
Corneal laceration
Large central defect with vision reduction
Organic material with high infection risk
Uncooperative patient
Pediatric patient unable to safely cooperate
Foreign body that cannot be safely visualized or accessed
Removal of a foreign body that is plugging a perforation can worsen the injury and increase the risk of serious complications. Deep metallic or organic foreign bodies may require ophthalmology referral because of the risk of perforation, scarring, or infection.
Examination Before Removal
A complete pre-removal evaluation should include:
Visual acuity before anesthetic if possible
External exam of lids and lashes
Slit lamp evaluation of the cornea
Fluorescein staining
Seidel testing if the defect is deep or suspicious
Eyelid eversion to look for retained subtarsal foreign bodies
Anterior chamber evaluation for cells, flare, hyphema, or hypopyon
Assessment of foreign body depth, location, and surrounding rust
Fluorescein staining helps identify the epithelial defect and can assist with Seidel testing when perforation is suspected. A positive Seidel test suggests aqueous leakage and requires urgent referral.
Supplies Commonly Used
Typical in-office supplies may include:
Topical anesthetic
Fluorescein strips
Sterile saline or eyewash
Cotton-tipped applicators
Sterile foreign body spud
25-gauge or 27-gauge sterile needle, when within scope and training
Jewelers forceps, when appropriate
Alger brush or ophthalmic burr for rust ring removal
Broad-spectrum topical antibiotic
Lubricating drops or ointment
Cycloplegic drop when indicated
Bandage contact lens when clinically appropriate and within provider preference
Protective shield if needed
The procedure should be performed under slit lamp magnification using sterile technique, good illumination, and careful patient positioning.
Step-by-Step Removal Technique
1. Explain the procedure and obtain consent
Explain that the goal is to remove the metallic fragment and as much rust as safely possible while minimizing corneal tissue disruption. Discuss that a residual epithelial defect is expected after removal and that follow-up is needed to confirm healing.
2. Instill topical anesthetic
Use topical anesthetic in-office to improve comfort and allow safe examination. Topical anesthetics should not be prescribed for home use because repeated use can delay healing and cause corneal toxicity.
3. Position the patient at the slit lamp
The patient should be stable, with forehead and chin properly positioned. Ask the patient to look in a direction that best exposes the foreign body.
4. Start with the least traumatic approach
If the foreign body is superficial, irrigation or a moistened sterile cotton-tipped applicator may remove it. If embedded, a sterile spud or needle may be required.
5. Approach tangentially
When using a spud or needle, approach the cornea tangentially rather than directly perpendicular to the eye. This reduces the risk of deeper corneal penetration. The goal is to gently lift or dislodge the foreign body, not dig into the cornea.
6. Remove the metallic fragment
Use controlled, small movements under magnification. Once dislodged, remove the fragment from the ocular surface. Recheck the surrounding cornea for residual material.
7. Reassess the cornea
After removal, stain with fluorescein again. Assess the size and depth of the epithelial defect, the presence of residual rust, and whether the anterior chamber remains quiet.
A final Seidel test is appropriate if there is a deep residual defect or any concern for penetration.
Rust Ring Removal
Metallic foreign bodies frequently leave a rust ring. Rust can be removed with a sterile spud, needle, or ophthalmic burr such as an Alger brush.
When using an Alger brush, the burr should be applied gently and tangentially. The spinning burr should do the work. Excessive pressure or aggressive debridement can enlarge the epithelial defect, deepen stromal tissue loss, increase healing time, and increase the risk of scarring.
The goal is not always to remove every trace of rust at the first visit. If the rust is deep, central, or removal would create excessive stromal disruption, it may be safer to remove the superficial rust and reassess in 24 hours. Some deeper rust can migrate anteriorly and be easier to remove at follow-up.
Post-Removal Treatment
After removal, management is similar to treating a corneal abrasion, with added attention to residual rust, infection risk, inflammation, and pain control.
Topical antibiotic
A broad-spectrum topical antibiotic is commonly used to reduce the risk of secondary bacterial keratitis. Antibiotic choice depends on the clinical scenario.
For non-contact lens wearers, common options may include:
Erythromycin ointment
Bacitracin-polymyxin ointment
Trimethoprim-polymyxin B drops
Fluoroquinolone drops when broader coverage is desired
For contact lens wearers, antipseudomonal coverage is typically preferred, often with a fluoroquinolone. Contact lens wear should be discontinued until the cornea is fully healed and the clinician clears the patient to resume wear.
Lubrication
Preservative-free artificial tears can improve comfort and support epithelial healing. Lubricating ointment may be useful at bedtime.
Cycloplegic therapy
If the patient has significant photophobia, ciliary spasm, or anterior chamber reaction, a short-acting cycloplegic may be considered. Cycloplegics can reduce pain from ciliary body spasm and improve comfort in selected cases.
Pain control
Oral analgesics such as acetaminophen or ibuprofen may be used when appropriate for the patient. Topical NSAIDs may be considered selectively, but they should be used cautiously because of concerns about delayed epithelial healing in some corneal injury cases.
Bandage contact lens
A bandage contact lens may be considered for larger epithelial defects or significant discomfort, depending on the provider’s training, comfort, and the patient’s risk profile. If a bandage contact lens is used, antibiotic coverage and close follow-up are important.
Follow-Up Schedule
Most metallic corneal foreign body patients should be rechecked within 24 hours, especially if there was:
Rust ring removal
Residual rust
Central corneal involvement
Moderate or large epithelial defect
Contact lens wear
Significant pain or photophobia
Anterior chamber reaction
Uncertain depth
Higher infection risk
At the follow-up visit, evaluate:
Visual acuity
Pain level
Size of the epithelial defect
Residual rust
Corneal infiltrate
Anterior chamber reaction
Wound stability
Seidel test if concern remains
Patient medication compliance
If the epithelial defect is improving and there is no infiltrate, treatment can usually continue until healed. If residual rust remains and is now more superficial, additional careful removal may be performed.
A second follow-up is often appropriate in 2 to 3 days if the defect has not fully healed, if residual rust remains, or if the injury was central. Continue monitoring until the epithelium is closed and the patient is clinically stable.
When to Escalate After Removal
Escalate or refer urgently if the patient develops:
Worsening pain
Decreased vision
Increasing redness
Corneal infiltrate
Hypopyon
Persistent epithelial defect
Enlarging defect
Increasing anterior chamber reaction
Positive or suspicious Seidel test
Dense central rust or scarring
Concern for infectious keratitis
Concern for retained intraocular foreign body
Delayed or incomplete treatment can increase the risk of corneal ulceration, stromal thinning, recurrent erosion, and visually significant scarring.
Patient Instructions After Removal
Patients should be told:
Do not rub the eye.
Do not wear contact lenses until cleared.
Use prescribed drops exactly as directed.
Use artificial tears for comfort if recommended.
Expect mild irritation and tearing while the cornea heals.
Call immediately for worsening pain, redness, discharge, light sensitivity, or decreased vision.
Wear protective eyewear during grinding, drilling, yard work, and metal work.
Clinical Pearls
Always document pre-removal visual acuity.
Always consider high-velocity trauma as a possible intraocular foreign body until ruled out.
Evert the upper lid to look for additional foreign material.
Use fluorescein before and after removal.
Perform Seidel testing when the defect is deep or suspicious.
Approach with a needle or spud tangentially, not straight into the cornea.
Remove rust conservatively when it is central or deep.
Do not enlarge a central scar zone unnecessarily.
Recheck most metallic foreign bodies in 24 hours.
Refer when depth, location, patient cooperation, or risk level makes in-office removal unsafe.
Conclusion
Metallic corneal foreign bodies are usually manageable in-office when they are superficial, well visualized, and not associated with penetrating trauma. Successful care depends on careful evaluation, safe removal technique, rust ring management, antibiotic prophylaxis, pain control, and close follow-up.
The most important clinical decision is knowing when to remove, when to observe residual rust, and when to refer. A thoughtful, conservative approach helps protect the cornea, reduce infection risk, and minimize visually significant scarring.
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