Intraocular Foreign Bodies

IOFB Definition & Types - The Unwanted Guest

An Intraocular Foreign Body (IOFB) is an object lodged within the eye.

• Definition:
  • Penetrating: Entry wound, no exit.
  • Perforating: Entry and exit wounds.
• Causes: Hammering (metal-on-metal), occupational hazards.
• Epidemiology: Young males. >50% of open globe injuries may have an IOFB.

Start["👁️ Suspected OGI
• Suspect IOFB• Emergent triage"] Life["⚠️ Life Threats
• Treat concurrents• Trauma protocols"] Exam["🩺 Eye Exam
• No IOP check• Apply eye shield"] Meds["💊 Systemic Tx
• IV Antibiotics• Tetanus shot"] CT["🔬 Orbit CT
• Without contrast• Confirm IOFB"] Globe["🩹 Globe Closure
• Proceed to repair• Surgical entry"] Immed["⚡ Immediate removal
• Organic or Toxic• Stable patient"] Delay["⏳ Delayed removal
• Severe edema• Unstable patient"] PPV["🔬 Small Gauge PPV
• 6mm infusion• AC infusion"] Lens["👁️ Lensectomy
• Lens involvement• Remove crystal"] Vit["✂️ Vitrectomy
• Mobilize IOFB• Biopsy/Cultures"] Remove["🧲 IOFB Removal
• Exit strategy• Instrumentation"] Repair["🩺 Retina Repair
• 360 Examination• Tamponade PRN"] Finish["✅ Final Steps
• Gas or Silicone• IVT Antibiotics"]

Start --> Life Life --> Exam Start --> Exam Exam --> Meds Meds --> CT CT --> Globe Globe -->|Organic| Immed Globe -->|Unstable| Delay Immed --> PPV Delay --> PPV PPV -->|Lens damage| Lens Lens --> Vit PPV --> Vit Vit --> Remove Remove --> Repair Repair --> Finish

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> ⭐ Most common IOFBs are metallic, often from hammering metal-on-metal.


## IOFB Diagnosis - Spotting the Intruder

Key diagnostic steps involve a thorough history, clinical examination, and appropriate imaging.

*   **History**
    -   Mechanism: High-speed projectile (e.g., hammering, explosion, grinding)?
    -   Material: Suspected type (metallic, glass, organic)?
*   **Symptoms**
    -   Pain (may be minimal), ↓ vision, floaters, photophobia.
*   **Signs**
    -   Entry wound (corneal/scleral): **Seidel's test positive** if aqueous leak present.
    -   Anterior segment: Hyphema, iris defect (e.g., transillumination, iridodialysis).
    -   Lens: Focal cataract.
    -   Posterior segment: Vitreous hemorrhage, cells.

**Imaging Modalities for IOFB Detection & Localization:**

| Imaging         | Key Features                                                                                                |
|-----------------|-------------------------------------------------------------------------------------------------------------|
| X-ray (AP/Lat)  | Detects radio-opaque FBs; poor localization. Bone-free views helpful.                                       |
| Ultrasound (B-scan) | Dynamic; good for posterior segment, FB detection/location, especially with opaque media.                   |
| CT Scan (orbital) | **Gold standard** for metallic IOFB; precise localization. Thin non-contrast axial & coronal cuts.          |
| MRI             | ⚠️ **Contraindicated** if metallic IOFB suspected (risk of movement/heating). Useful for non-metallic FBs. |![Intraocular foreign body on CT and B-scan](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Ophthalmology_Ocular_Trauma_Intraocular_Foreign_Bodies/d1ca9cb1-80ab-4873-9d8a-9a40b648d2b2.png)

> ⭐ Non-contrast CT scan (thin axial and coronal slices) is the investigation of choice for suspected IOFB due to its high sensitivity and specificity for metallic FBs and precise localization ability. 

## IOFB Management - Damage Control Tactics

**Initial Management (Pre-operative):**
*   Protect the eye: Rigid eye shield (NO patching).
*   NPO (Nil Per Oral): In anticipation of surgery.
*   Systemic Prophylaxis:
    -   Tetanus toxoid (IM/IV) as per status.
    -   Broad-spectrum IV antibiotics (e.g., Vancomycin + Ceftazidime).
*   Topical broad-spectrum antibiotics (e.g., Moxifloxacin 0.5% q1h).
*   Control pain & nausea: Analgesics (e.g., Paracetamol) & Antiemetics (e.g., Ondansetron).

**Surgical Management:**
*   **Timing:** Urgent, ideally within **24-72 hours** of injury (↓ endophthalmitis risk).
*   **Anesthesia:** General Anesthesia (GA) preferred for controlled environment.

**Surgical Approach Decision:**
```mermaid
%%{init: {'flowchart': {'htmlLabels': true}}}%%
flowchart TD

Start["<b>👁️ IOFB Confirmed</b><br><span style='display:block; text-align:left; color:#555'>• Intraocular FB</span><span style='display:block; text-align:left; color:#555'>• Imaging complete</span>"]

Loc["<b>❓ IOFB Location?</b><br><span style='display:block; text-align:left; color:#555'>• Clinical exam</span><span style='display:block; text-align:left; color:#555'>• Assess depth</span>"]

AntApp["<b>🔪 Anterior Approach</b><br><span style='display:block; text-align:left; color:#555'>• Limbal incision</span><span style='display:block; text-align:left; color:#555'>• Corneal incision</span>"]

PostApp["<b>💉 Posterior Approach</b><br><span style='display:block; text-align:left; color:#555'>• Pars plana vitrectomy</span><span style='display:block; text-align:left; color:#555'>• PPV technique</span>"]

AntRem["<b>💊 Remove FB</b><br><span style='display:block; text-align:left; color:#555'>• AC/Lens removal</span><span style='display:block; text-align:left; color:#555'>• +/- Lensectomy</span>"]

PostRem["<b>💊 PPV Removal</b><br><span style='display:block; text-align:left; color:#555'>• Vitreous/Retina FB</span><span style='display:block; text-align:left; color:#555'>• +/- Lensectomy</span>"]

Start --> Loc
Loc -->|Anterior Seg| AntApp
Loc -->|Posterior Seg| PostApp
AntApp --> AntRem
PostApp --> PostRem

style Start fill:#F7F5FD, stroke:#F0EDFA, stroke-width:1.5px, rx:12, ry:12, color:#6B21A8
style Loc fill:#FEF8EC, stroke:#FBECCA, stroke-width:1.5px, rx:12, ry:12, color:#854D0E
style AntApp fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534
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style PostRem fill:#F1FCF5, stroke:#BEF4D8, stroke-width:1.5px, rx:12, ry:12, color:#166534

• FB Removal Techniques: Intraocular forceps, magnet (for magnetic FBs), or viscoexpression.
• Lensectomy: Performed if lens is cataractous, significantly damaged, or harbors FB.
• Prophylaxis: Intravitreal antibiotics (e.g., Vancomycin + Ceftazidime) at the end of surgery.

⭐ For magnetic IOFBs, an external electromagnet or intraocular rare-earth magnet can be used during PPV for controlled extraction, minimizing retinal trauma.

IOFB Complications & Prognosis - Aftermath & Alerts

• Complications:

  • Endophthalmitis: Most feared (risk 2-13%); prophylactic antibiotics vital.

    ⭐ Endophthalmitis is the most devastating complication of IOFB, significantly worsening visual prognosis.

  • Sympathetic ophthalmia.
  • Retinal detachment (tractional, rhegmatogenous).
  • Metallosis (details below).

• Metallosis: Siderosis vs. Chalcosis

  Feature	Siderosis Bulbi (Iron)	Chalcosis (Copper >85%)
  Key Signs	📌 Iris heterochromia, Rust spots (retinal degen.), Open-angle glaucoma, Night blindness, mydriasis, cataract	Kayser-Fleischer ring, sunflower cataract, uveitis, green iris
  ERG	↓ b-wave > a-wave, then extinguished	Initially supernormal, then ↓, finally extinguished

• Prognosis:

  • FB: Size, type (Fe/Cu worse), location (posterior).
  • Initial VA (key).
  • Associated trauma.
  • Time to repair.
  • Endophthalmitis presence.

High‑Yield Points - ⚡ Biggest Takeaways

• History of hammering strongly suggests an Intraocular Foreign Body (IOFB).
• CT scan (non-contrast) is gold standard for IOFB localization; X-ray orbit for screening.
• MRI is contraindicated with suspected metallic IOFB due to movement risk.
• Siderosis bulbi (iron) & chalcosis (copper >85%) are key chronic complications.
• Urgent surgical removal, often via pars plana vitrectomy (PPV), is standard.
• Prophylactic antibiotics (systemic, topical) are vital to prevent endophthalmitis.
• Double perforation carries a poorer prognosis.