Intraocular Foreign Body

Key Points at a Glance

Key Points of This Disease

• Intraocular foreign bodies (IOFB) are associated with 18–41% of open globe injuries (OGI), most commonly in men aged 21–40 with workplace injuries.
• CT is the first-choice imaging modality, detecting IOFB in up to 95% of cases. MRI is contraindicated if a metallic foreign body is suspected.
• Pars plana vitrectomy (PPV) is the standard removal method for posterior segment foreign bodies (58–88%).
• Primary repair within 24 hours of injury is an independent protective factor against endophthalmitis.
• Iron foreign bodies left untreated cause siderosis (retinal degeneration, cataract, glaucoma); copper foreign bodies cause chalcosis (panophthalmitis, sunflower cataract).
• The Ocular Trauma Score (OTS) can predict final visual prognosis at the time of injury.
• If the foreign body material is inert (glass, plastic), retention may be an option under certain conditions.

1. What is an Intraocular Foreign Body?

An intraocular foreign body (IOFB) is a foreign object that penetrates the eye wall from outside and remains inside the eye. It is a form of open globe injury (OGI) and is an ophthalmic emergency that significantly affects visual prognosis. Metal fragments, glass shards, plastic pieces, wood chips, etc., enter the eye during hammering, grinding, drilling, using automatic lawn mowers, explosions, or traffic accidents, often in factories or workplaces. Most are small metallic foreign bodies entering through the corneoscleral junction. The time to removal greatly influences visual prognosis, so early diagnosis and prompt removal are essential.

Epidemiology

The incidence of OGI in the United States is 4.5 per 100,000 per year, and IOFB accounts for 18–41% of OGI ¹⁾. Globally, the number of IOFB cases per million population increased from 350 in 2008 to over 450 in 2019 ¹⁾. The most common patient group is men aged 21–40, with injuries occurring at work in 54–72% and at home in about 30% of cases ¹⁾. It is common among workers in metal manufacturing, processing, and construction, with metal fragments (iron, copper, lead, etc.) accounting for the majority.

Anatomical Classification (Zone of Injury)

The Zone of Injury classification is used for severity grading based on the injured site¹⁾.

• Zone 1: Corneal and limbal injury (best prognosis)
• Zone 2: Scleral injury up to 5 mm posterior to the limbus
• Zone 3: Scleral injury more than 5 mm posterior to the limbus (posterior segment injury, poor prognosis)

Location and Material of Foreign Body

Frequency by Location

Posterior segment (vitreous, retina): Accounts for 58–88% of all IOFBs. Most common.

Anterior segment (anterior chamber, iris, lens): 10–15%.

Lens and orbit: 2–8%.

Types of Material

Metals: Iron, copper, lead, zinc, aluminum, nickel, etc. Most common.

Non-metals: Glass, plastic, stone, wood, plant matter, etc.

Organic materials: Wood, fiber, plant matter. Strong tissue reaction and high risk of endophthalmitis.

Classification by Location

Intraocular foreign bodies are classified into the following five types based on their location.

1. Anterior chamber and iris
2. Within the lens
3. Within the vitreous
4. Retina or subretinal
5. Choroid or sclera

Q If a small metal particle enters the eye but causes no symptoms, is it okay not to see a doctor?

A

A small iron particle may not be noticed at the time of injury. However, if left untreated, siderosis can gradually reduce vision. If you experience floaters or vision changes after metalworking, you should promptly see an ophthalmologist.

2. Main symptoms and clinical findings

Suspected intraocular foreign body, corneal laceration, and lens capsule rupture

Hwang HJ, et al. Lenticular fungal infection caused by Aspergillus in a patient with traumatic corneal laceration: a case report. BMC Ophthalmol. 2020. Figure 1. PMCID: PMC7195745. License: CC BY.

Full-thickness corneal laceration (a), anterior capsule rupture with suspected foreign body (b), and B-mode ultrasound image showing no intraocular foreign body (c). These correspond to intraocular foreign bodies discussed in section “2. Main symptoms and clinical findings.”

Subjective symptoms

• Eye pain: Pain associated with penetrating wound. May be mild with small metal particles.
• Tearing and foreign body sensation: Associated with perforating wound or corneal damage.
• Visual impairment: Depends on location, size of foreign body, and complications (cataract, retinal damage).
• Floaters: Caused by vitreous hemorrhage or shadow of the foreign body.
• Hyperemia: Ciliary injection to severe hyperemia.

Note that with very small foreign bodies like iron filings, the patient may be unaware of the injury. Symptoms include eye pain, tearing, and visual impairment. If a corneal perforation is present with leakage, hypotony and shallow anterior chamber often occur.

Clinical Findings

Clinical findings of open globe injury are diverse. If globe rupture is suspected, avoid using applanation tonometry for intraocular pressure measurement ¹⁾. Up to 55% of IOFBs are undetectable by clinical examination alone, so imaging is essential ¹⁾.

• Perforating wound: Full-thickness injury of cornea or sclera. Observed as an irregular laceration.
• Positive Seidel test: Aqueous humor leakage confirmed by fluorescein staining.
• Hypotony and shallow anterior chamber: Due to aqueous humor leakage.
• Hyphema (anterior chamber hemorrhage): Associated with trauma.
• Traumatic cataract: Due to lens damage or accumulation of iron or copper ions.
• Relative afferent pupillary defect (RAPD): Suggests severe optic nerve or retinal damage. Confirming RAPD is important for prognosis ¹⁾.

Q If vision is good after a foreign body enters the eye, is an examination still necessary?

A

Even if vision is preserved, a foreign body may remain inside the eye. Particularly, iron filings or copper fragments can cause siderosis or chalcosis if left untreated, leading to vision loss months to years later. It is important to visit an ophthalmologist immediately after injury and undergo CT to rule out IOFB.

3. Causes and Risk Factors

Mechanism of Injury

The most common mechanism of IOFB is hammering metal (59%) ⁵⁾. Other main mechanisms are listed below.

• Grinding/lathe work: Metal fragments scattering due to high-speed rotation ¹⁾
• Nail gun: Intraocular penetration of nails ⁵⁾
• Explosives/military trauma: Multiple foreign bodies may affect both eyes ³⁾
• Household work: Improper use of tools

Risk Factors

• Not wearing eye protection: The largest preventable risk ¹⁾
• Male, 21–40 years old: Group with high occupational exposure risk ¹⁾
• Rural environment: High risk of endophthalmitis due to soil bacteria (Bacillus cereus) ¹⁾

Infection Risk

The overall rate of endophthalmitis complicating IOFB is 5–30% (average 6.5%) ¹⁾. Rural areas, organic foreign bodies, and delayed treatment increase the risk.

Foreign Body Material and Tissue Toxicity

The effect on tissue varies greatly depending on the material of the foreign body.

Material	Toxicity	Main Complications
Iron/Steel	Moderate	Siderosis (chronic)
Copper (pure copper)	High	Chalcosis / Panophthalmitis
Glass/Plastic	Low (inert)	May be left in place

Importance of wearing eye protection

When working with metal, grinders, or nail guns, always wear protective eyewear that complies with ANSI standards or equivalent. 54–72% of IOFBs occur in the workplace, and most can be prevented by wearing protective equipment. After a foreign body enters the eye, never rub the eye; protect it with a shield and see an ophthalmologist immediately.

Q How should I protect my eyes during work?

A

When using a grinder or hammer, there is a risk of intraocular foreign body from flying metal fragments. Always wear protective eyewear (goggle type preferred) that meets ANSI or JIS standards. 54–72% of IOFBs occur in the workplace, and most can be prevented with appropriate protective equipment¹⁾.

4. Diagnosis and Examination Methods

Imaging Diagnosis

Imaging is essential for localizing intraocular foreign bodies. It is important to determine whether the foreign body is magnetic (iron) or non-magnetic (copper, aluminum, lead, zinc, glass, wood), and a detailed history of the injury should be obtained. The characteristics of each modality are described below.

Test	Detection sensitivity	Notes
CT	Up to 95%	First choice. Effective for metal, glass, and stone
X-ray (Waters view)	Metal fragments ≥2 mm	Low sensitivity. Screening only
MRI	—	Absolute contraindication for metallic IOFB

• CT (computed tomography): Detects IOFB with up to 95% sensitivity and is the first-choice imaging modality ¹⁾. Axial and coronal sections allow assessment of the location, number, and material of the foreign body. Simultaneous evaluation of orbital and intracranial changes is possible.
• Plain X-ray (Waters view): Orbital radiography is performed. A 10-yen coin (approximately 24 mm in diameter) is used as a reference to determine whether the foreign body is intraocular or extraocular, but sensitivity is low and it is only a screening aid.
• MRI: If a metallic IOFB is present, it is an absolute contraindication because it may cause additional damage due to movement or rotation of the magnetic material ¹⁾. Consider performing only if non-metallic nature is confirmed by imaging or history.
• B-scan ultrasound: The detection sensitivity for IOFB is low at about 52% ¹⁾, but it is useful for evaluating posterior vitreous detachment, retinal detachment, and the eyewall. It is also used to detect glass or plastic foreign bodies not visualized by CT.
• Comberg method: Once an intraocular foreign body is identified, confirm its location using the Comberg method.

Infection Management

Regardless of the location of the foreign body, consider the possibility of infection and perform bacterial and fungal culture of intraocular fluid.

Severity Prediction: Ocular Trauma Score (OTS)

OTS is a prognostic score that predicts final visual acuity based on initial visual acuity at the time of injury, presence of globe rupture, endophthalmitis, perforation, retinal detachment, and RAPD ¹⁾. It is used to guide treatment decisions and patient counseling.

Q Metal may have entered the eye. Can I undergo an MRI?

A

If a metallic IOFB is suspected, do not undergo MRI. Magnetic foreign bodies can move in the MRI magnetic field, causing additional intraocular damage ¹⁾. First, evaluate the presence and material of the foreign body with CT; consider MRI only if non-metallic nature is confirmed.

5. Standard Treatment

Initial Management (Preoperative)

• Eye shield protection: Protect the eye with a rigid shield to avoid direct pressure on the globe.
• NPO and systemic management: Prepare for emergency surgery.
• Check tetanus immunization: Perform as a routine measure for trauma ¹⁾.
• Systemic antibiotic administration: Administer broad-spectrum intravenous antibiotics for possible infection. Initiate to prevent endophthalmitis.

Recommended systemic antibiotic regimen¹⁾:

• Levofloxacin 500 mg/day (oral)
• or Moxifloxacin 400 mg/day (oral)
• Severe/rural cases: Vancomycin 1 g every 12 hours (IV) + Ceftazidime 1 g every 8 hours (IV)

Primary Repair (Open Wound Closure)

Open globe injuries should undergo primary closure first. Suture material guidelines are as follows¹⁾.

• Corneal laceration: 10-0 nylon suture
• Limbus laceration: 9-0 nylon suture
• Scleral laceration: 8-0 Vicryl suture

Primary repair within 24 hours of injury is an independent protective factor against endophthalmitis¹⁾⁷⁾.

Foreign Body Removal (Surgical Treatment)

Once an intraocular foreign body is confirmed, prompt removal as soon as possible leads to better visual prognosis in terms of both tissue reconstruction and infection control.

Anterior Segment Foreign Body

Removal method: After maintaining the anterior chamber with viscoelastic material, remove with forceps through a corneoscleral incision.

Magnetic foreign body: An external magnet can also be used for small iron fragments in the anterior segment.

Indications: IOFB in the anterior chamber, iris, or lens.

Posterior Segment Foreign Body

Standard procedure: Small-incision pars plana vitrectomy (PPV) using 23G/25G/27G is standard¹⁾.

Large foreign body (>4 mm): Removed via a corneoscleral tunnel incision¹⁾.

Use of PFCL: Macular protection with liquid perfluorocarbon (PFCL) is controversial¹⁾.

Details of Removal by Location

Anterior chamber, angle, and iris foreign bodies: Create a sufficiently wide corneoscleral incision, inject enough viscoelastic into the anterior chamber to maintain space, and ensure the foreign body does not move. Then remove it with forceps, taking care not to damage the corneal endothelium or lens.

Intralenticular foreign body: Inject sufficient viscoelastic into the anterior chamber, then remove the foreign body with a magnet or forceps. If the posterior capsule is intact, proceed with standard cataract surgery and intraocular lens implantation. If the posterior capsule is damaged, perform vitrectomy.

Vitreoretinal foreign body: For large magnetic foreign bodies with a large corneal perforation, removal with a giant magnet is possible. Generally, vitrectomy is performed using an intraocular magnet, microforceps, or diamond forceps, creating a wound at the limbus or pars plana corresponding to the size of the foreign body.

Choroidal/scleral foreign body: Similar to scleral buckling, visualize the fundus, perform a partial-thickness scleral incision over the foreign body, remove it with a magnet or forceps, and then perform cryocoagulation.

Removal Devices

• Diamond-coated forceps: Enhance grip on smooth IOFBs¹⁾
• NCircle nitinol basket: Basket removal of difficult-to-grasp foreign bodies¹⁾
• Conventional electromagnet/permanent magnet: Used for ferromagnetic foreign bodies

Intravitreal Antibiotic Administration

Intravitreal administration is performed according to the risk of endophthalmitis. Recommended drugs and doses are shown below ¹⁾. Antibiotics are also added to the vitrectomy perfusion fluid in accordance with vitrectomy for bacterial endophthalmitis.

Drug	Dose	Indication
Vancomycin	1.0 mg/0.1 mL	Gram-positive coverage
Ceftazidime	2.25 mg/0.1 mL	Gram-negative coverage
Voriconazole	50–100 μg/0.1 mL	Rural areas/soil contamination cases (fungal risk) 1)3)

Timing of Removal

The urgency varies depending on the material of the foreign body ¹⁾.

• Immediate removal required: Toxic metals (iron, copper), organic materials (risk of endophthalmitis, tissue reaction)
• Elective removal possible: Inert foreign bodies such as glass, plastic
• Military trauma: Under antibiotic management, no endophthalmitis reported even with an average delay of 21 days¹⁾

Repair of posterior scleral perforation

For large perforations of the posterior sclera, a three-layer plug (filled from the inside) using donor sclera, amniotic membrane, and fibrin glue has been reported to be effective⁴⁾.

Treatment precautions

• If globe rupture is suspected, absolutely avoid direct pressure on the eye and applanation tonometry.
• Primary repair within 24 hours is key to preventing endophthalmitis¹⁾⁷⁾.
• Remove toxic metals (iron, copper) without delay. Leaving them can cause siderosis or chalcosis.
• Carefully manage systemic conditions while avoiding rapid drops in blood pressure or fluctuations in intraocular pressure.

Q How soon after injury is surgery necessary?

A

Primary repair of open globe injuries is recommended within 24 hours. Repair within 24 hours has been reported as an independent protective factor against endophthalmitis¹⁾⁷⁾. Toxic metals (iron, copper) and organic foreign bodies should be removed immediately in principle, while inert foreign bodies such as glass may sometimes be managed electively.

Q Is it always necessary to surgically remove a foreign body?

A

It depends on the material. Toxic metals such as iron and copper, and organic materials are generally removed due to the risk of tissue damage and endophthalmitis. Inert foreign bodies such as glass or plastic may be left in place if the risk of removal complications is high¹⁾. Individual assessment by an ophthalmologist is necessary.

6. Pathophysiology and detailed mechanism

Siderosis bulbi

When a ferrous foreign body remains in the eye, iron ionizes into ferrous and ferric forms, diffuses throughout the eye, and accumulates in various tissues²⁾.

• Deposition sites: Deposits in corneal epithelium, iris pigment epithelium, ciliary body epithelium, lens epithelium, and retinal pigment epithelium (RPE).
• Clinical findings: Heterochromia iridis (darker color on the affected side), fixed dilated pupil, and brown deposits under the anterior lens capsule.
• Tissue damage: Retinal pigment epithelium toxicity → photoreceptor degeneration → night blindness, visual field constriction → blindness
• Secondary complications: Traumatic cataract, secondary glaucoma, retinal degeneration
• Course: Slowly progressive over months to years.

Chalcosis bulbi

The toxicity of copper foreign bodies depends on the purity of the copper. Copper has an affinity for basement membranes such as the internal limiting membrane.

• Pure copper (high purity): Causes fulminant panophthalmitis, rapidly damaging the eye.
• Alloy (low-purity copper): Chronically produces Kayser-Fleischer (KF) rings (copper deposition in the peripheral cornea), anterior subcapsular cataract, and green deposits under the internal limiting membrane.
• Retina: Metallic sheen retinopathy may appear.

Organic foreign bodies

Plant fragments, wood chips, cotton fibers, etc., cause severe granulomatous tissue reaction and endophthalmitis¹⁾. In principle, immediate removal is necessary. However, cotton fibers that have strayed after intravitreal injection are relatively inert and may not require removal⁶⁾.

Complete choroidal incarceration cases

When a foreign body is completely embedded in the choroid, removal may be technically impossible ⁵⁾. If long-term inflammation persists, enucleation of the eye may be necessary.

Course and Complications

Postoperatively, there is a possibility of progression to proliferative vitreoretinopathy (PVR). If the uvea is severely damaged, sympathetic ophthalmia may develop. Maximum attention must also be paid to endophthalmitis.

7. Latest Research and Future Perspectives (Investigational Reports)

For Patients: Please Read Carefully

The following content is currently under investigation or in clinical trials and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

JIN Magnetic Foreign Body Extractor (New Generation Magnetic Extraction Device)

Zhao et al. (2025) reported a novel magnetic foreign body extractor (JIN magnetic foreign body extractor) using a rare earth-gold alloy ²⁾. It is compatible with 20–27G ports and allows foot pedal-controlled on/off switching of magnetic force ranging from 254 to 86.3 Gauss-seconds (Gs). The importance of early removal to prevent retinal pigment epithelial toxicity due to iron ion release is also emphasized ²⁾.

Three-Layer Plug Technique for Posterior Perforation

Celo et al. (2023) reported a technique for internal closure of posterior perforations using a three-layer plug combining donor sclera, amniotic membrane, and fibrin glue ⁴⁾. This is noted as an alternative procedure for posterior perforations where conventional external suturing is difficult.

Simultaneous Bilateral Surgery

Mishra et al. (2023) performed simultaneous bilateral vitrectomy by two surgeons in two cases of bilateral open globe trauma caused by explosives ³⁾. This reduced general anesthesia time compared to sequential surgery by a single surgeon and is considered a useful option in managing bilateral ocular trauma.

Meta-Analysis of Primary Repair Timing

McMaster et al. (2025) published a systematic review and meta-analysis of primary repair timing in open globe injuries ⁷⁾. Repair within 24 hours is an independent protective factor against endophthalmitis, supporting the benefit of early repair as the latest evidence.

Iatrogenic Intraocular Foreign Bodies

Drnovsek et al. (2022) reported a case of a cotton fiber that migrated into the vitreous cavity after intravitreal injection ⁶⁾. Cotton fibers are relatively inert, and observation or endoscopic removal should be considered. Awareness of iatrogenic IOFB is increasing.

Psychological impact of pediatric IOFB

Reports indicate that 15% of pediatric patients develop GAD, PTSD, or depression after trauma, highlighting the importance of psychological support alongside ophthalmic treatment ¹⁾.

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8. References

1. Ohlhausen M, Yonekawa Y, Mahmoud TH. Advances in the management of intraocular foreign bodies. Front Ophthalmol. 2024;4:1422466.
2. Zhao X, Jin Y, Wang Z, et al. Extraction of magnetic intraocular foreign bodies using a novel magnetic foreign body extractor. Case Rep Ophthalmol. 2025;16:720-727.
3. Mishra K, Brinton JP, Shah AS, et al. Simultaneous bilateral open-globe repair and vitreoretinal surgery for explosive-related injury. J VitreoRetinal Dis. 2023;7(6):540-544.
4. Celo E, Risi F, Muccioli C. Internal plugging of traumatic posterior perforation using donor sclera, amniotic membrane, and fibrin glue. J VitreoRetinal Dis. 2023;7(6):536-539.
5. Epstein A, Majeed S, Han S, et al. Traumatic intrachoroidal nail implantation. Proc (Bayl Univ Med Cent). 2022;35(1):106-107.
6. Drnovsek F, Lumi X. Intravitreal cotton fiber foreign body after intravitreal injection. Case Rep Ophthalmol. 2022;13:529-533.
7. McMaster C, Borschel GH, Kapoor M, et al. Early versus delayed timing of primary repair after open-globe injury. Ophthalmology. 2025;132:431-441.