What is the procedure for a patient with a foreign body in their eye, considering their past medical history and potential for vision loss?

Foreign Body Eye Examination Procedure

Immediately test visual acuity to establish baseline function and identify acute vision loss requiring urgent ophthalmology referral, then proceed with a systematic examination prioritizing identification of globe penetration and sight-threatening injuries. 1

Initial Assessment and Red Flags

Critical History Elements

• Mechanism of injury is paramount: High-velocity mechanisms (grinding, metal work, hammering, nailing) carry significantly higher risk of globe penetration and require immediate ophthalmology consultation 1, 2
• Document timing of trauma, nature of foreign body material (especially metallic vs. organic), and velocity of impact 3
• Ask specifically about diplopia, vision loss, pain severity, and photophobia 3, 1
• Contact lens wear at time of injury requires immediate lens removal and discontinuation 1, 2

Vision-Threatening Red Flags Requiring Emergency Referral

• Irregular pupil after trauma indicates penetrating injury 1, 2
• Eye bleeding or acute vision loss 1, 2
• Visible corneal damage with ulceration, haze, opacity, or purulent discharge 1
• Suspected intraocular foreign body 4

Systematic Examination Protocol

Primary Examination Components

Perform the following in sequence to rule out globe injury or sight-threatening pathology 3:

• Visual acuity testing (document baseline) 3, 1
• Pupillary examination (check for irregularity suggesting penetration) 3, 1
• Intraocular pressure measurement 3
• Confrontational visual field testing 3
• Slit-lamp biomicroscopy to evaluate:
  • Corneal epithelium for defects, foreign body location, depth, and rust ring 1
  • Anterior chamber for cells (≥1+ cells requires cultures) 1
  • Iris defects or peripheral anterior synechiae 5
• Fluorescein staining to identify epithelial defects and differentiate from pooling 1
• Evert the eyelid to inspect tarsal conjunctiva for retained foreign bodies 1
• Dilated fundus examination (if safe) with attention to torsion, retinal damage, and posterior foreign bodies 3
• Exophthalmometry if orbital trauma suspected 3

Additional Testing for Trauma Cases

• Forced duction and forced generation testing to distinguish restriction from paresis 3
• Facial sensation testing 3
• Vital signs monitoring for bradycardia, heart block, dizziness, nausea, or vomiting—these may indicate oculocardiac reflex from entrapped muscle, which is life-threatening 3

Imaging Considerations

When to Image

• CT scan (not MRI) is required if any concern exists for ferrous-metallic foreign body 3, 6
• CT provides sufficient information about orbital fractures and entrapment 3
• MRI provides more precise extraocular muscle imaging but is contraindicated with metallic foreign bodies due to risk of movement causing hyphema or other injury 6

Critical pitfall: Even thorough pre-MRI screening questionnaires may fail to detect retained metallic foreign bodies, as patients may not understand the thoroughness of prior foreign body removal 6

Topical Anesthesia for Examination

For foreign body removal or detailed examination, instill 1-2 drops of proparacaine hydrochloride 2-3 minutes prior to the procedure 7

Post-Examination Management

If Foreign Body Identified and Removed

• Broad-spectrum topical antibiotic prophylaxis (moxifloxacin four times daily or gatifloxacin) 1, 4
• Topical NSAID (ketorolac) for pain, photophobia, and foreign body sensation 1, 4
• Cycloplegic agent (cyclopentolate) to reduce ciliary spasm pain 1, 4
• Oral acetaminophen or NSAIDs for additional pain relief 1, 2, 4

Mandatory Follow-Up

All patients require ophthalmology follow-up within 24-48 hours to monitor for infection development, assess for rust ring formation with metallic foreign bodies, and ensure complete removal 1

Indications for Cultures

Obtain cultures for 1:

• Corneal foreign bodies with associated infiltrates (especially central, large, or with stromal involvement/melting)
• ≥1+ cells in anterior chamber
• Multiple corneal infiltrates or atypical features

Special Considerations

Orbital Trauma with Muscle Entrapment

Immediate surgical repair is indicated for CT evidence of entrapped muscle with nonresolving oculocardiac reflex or "white-eyed blow-out fracture" in children 3

Delayed Presentations

Retained intraocular foreign bodies may remain asymptomatic for years before causing chronic inflammation, pain, siderotic glaucoma, or vision loss 8, 9. Inert materials like fiberglass can leave the eye without inflammation, making diagnosis particularly challenging 5. Maintain high suspicion even with normal initial fundus examination—CT and ultrasound biomicroscopy may be necessary to detect occult foreign bodies 9

Patient Warning Signs to Return Immediately

Instruct patients to return for 1, 2:

• Worsening pain or vision
• Increasing redness
• Discharge or purulent material
• Persistent foreign body sensation despite treatment