Ophthalmology · Ocular Trauma
The facts most likely to be tested
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Slit-lamp examination identifies the corneal foreign body; fluorescein staining with cobalt blue light detects the associated epithelial defect and Seidel sign.
Seidel sign, the streaming of aqueous humor that dilutes fluorescein at a wound site, indicates an open globe injury (full-thickness eyewall wound).
Metallic foreign bodies often leave a rust ring if not removed within 24 hours, requiring referral to ophthalmology for specialized removal.
High-velocity injuries, such as those involving hammering or grinding, mandate a CT scan of the orbit to rule out an intraocular foreign body.
Topical anesthetic drops are used for initial examination but are contraindicated for home use due to the risk of corneal melting and delayed healing.
Visual acuity must be assessed and documented in both eyes prior to any manipulation or irrigation of the affected eye.
Tetanus prophylaxis status must be updated if the foreign body is contaminated or if the injury involves a penetrating wound.
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A 34-year-old construction worker presents to the emergency department complaining of a persistent foreign body sensation in his right eye after grinding metal without protective eyewear. On physical examination, his visual acuity is 20/20 bilaterally. Slit-lamp examination reveals a small metallic fragment embedded in the central cornea with a positive Seidel sign. The patient denies any vision loss or pain beyond the initial irritation.
What is the most appropriate next step in management?
Place a rigid eye shield and obtain emergent ophthalmology consultation for open globe injury (corneal laceration).
The presence of a positive Seidel sign indicates a full-thickness corneal laceration - an open globe (penetrating) injury - which is an ocular emergency requiring a rigid shield, no further manipulation, and immediate specialist intervention.
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High yield triage
Etiology / Epidemiology
Common in metalworkers and construction laborers. High-velocity projectiles are the primary risk factor for intraocular penetration.
Clinical Manifestations
Presents with foreign body sensation and tearing. Seidel sign indicates an open globe injury.
Diagnosis
Perform fluorescein staining with cobalt blue light. Use CT orbit without contrast for suspected metallic intraocular objects.
Treatment
Remove superficial bodies with sterile saline irrigation or moist cotton swab. Do not use topical anesthetics for long-term pain control.
Prognosis
Most superficial cases resolve without sequelae. Endophthalmitis is the most feared complication.
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Epidemiology & Etiology
Most cases occur in young males during grinding, drilling, or hammering. High-velocity particles often bypass the blink reflex. Always suspect intraocular foreign body (IOFB) if the mechanism involves power tools or hammering on metal.
Pertinent Anatomy
The cornea is the most common site for superficial foreign bodies. The limbus is the transition zone between the cornea and sclera. Penetrating injuries often involve the sclera or cornea, potentially damaging the iris or lens.
Pathophysiology
Superficial bodies cause mechanical irritation of the corneal epithelium, triggering reflex lacrimation. Intraocular bodies may cause mechanical trauma, introduce infection, or induce chemical toxicity (e.g., siderosis from iron). Inflammation leads to secondary uveitis and potential vision loss.
Clinical Manifestations
Patients report a foreign body sensation, photophobia, and blurred vision. Red flags include a teardrop-shaped pupil, shallow anterior chamber, or Seidel sign (streaming of aqueous humor). Always assess visual acuity before any manipulation.
Diagnosis
Perform a comprehensive eye exam including slit lamp examination. Use fluorescein staining to identify epithelial defects; the dye will pool in the abrasion. If an intraocular foreign body is suspected, obtain a CT orbit (non-contrast) to localize metallic objects. MRI is contraindicated when a metallic intraocular foreign body is possible because of ferromagnetic migration.
Treatment
Irrigate the eye with normal saline to dislodge loose particles. Only after open globe injury has been excluded (negative Seidel sign) may a trained provider remove an embedded superficial corneal body with a sterile needle or burr under topical anesthetic. Never manipulate or apply pressure to a suspected open globe - shield and refer. Never prescribe topical anesthetics for home use due to risk of corneal melting. Prescribe a topical antibiotic (e.g., erythromycin ointment; a fluoroquinolone for contact lens wearers) for prophylaxis.
Prognosis
Superficial abrasions typically heal within 24-48 hours. Endophthalmitis is a catastrophic infection requiring urgent ophthalmology referral. Monitor for corneal ulceration or persistent vision changes.
Differential Diagnosis
Corneal abrasion: absence of visible foreign body
Corneal ulcer: white infiltrate present on slit lamp
Conjunctivitis: diffuse injection without focal foreign body
Globe rupture: positive Seidel sign and irregular pupil
Chemical burn: history of exposure and abnormal pH