Intraocular Foreign Body

A foreign body that has passed through the cornea or sclera and lodged inside the globe. It occurs in about 20 to 40 percent of open globe injuries from projectiles.

• Typical scenario: a young male worker hammering metal on metal or grinding without eye protection; also explosions, firearms (shotgun pellets, air gun), glass, wood and stone.
• Material determines toxicity:
  • Iron and steel: siderosis bulbi (iron deposits in retinal pigment epithelium, lens epithelium and iris cause retinal degeneration, cataract, and iris heterochromia).
  • Copper: chalcosis (acute sterile endophthalmitis; pure copper is the most toxic), brass less toxic.
  • Inert: glass, plastic, stone, gold, lead, platinum, aluminium.
  • Organic (wood, vegetable matter, soil): high risk of endophthalmitis (including fungal) and abscess.
• Complications: endophthalmitis (3 to 48 percent, highest with organic and delayed removal), traumatic cataract, retinal detachment, vitreous haemorrhage, proliferative vitreoretinopathy, and sympathetic ophthalmia.

• A history of high speed metal projectile; reduced vision, pain, redness.
• Entry wound (corneal or scleral laceration, often self-sealing, with iris transillumination defect or prolapse), irregular or peaked pupil, hyphaema, anterior chamber flare, localised lens opacity or cataract, vitreous haemorrhage, visible foreign body in the anterior chamber, lens, vitreous or on the retina, retinal tear or detachment, and low intraocular pressure.
• Late: siderosis (rusty discolouration of iris, lens deposits, pigmentary retinopathy, raised intraocular pressure) and chalcosis (Kayser-Fleischer-like ring, sunflower cataract).
• Endophthalmitis: severe pain, hypopyon, loss of vision.

• High clinical suspicion with any suggestive history, even when the eye looks well.
• CT orbits with thin (1 mm or less) axial and coronal slices (sensitivity above 95 percent for metal; lower for wood and glass); B-scan ultrasound with care (open globe) and ultrasound biomicroscopy for anterior foreign bodies; plain radiographs are inadequate.
• MRI contraindicated if the foreign body may be ferromagnetic; may be useful for wood and plastic after magnetic metal is excluded.
• Gonioscopy for angle foreign body; dilated fundus examination.
• Electroretinogram for siderosis monitoring.
• Culture of aqueous and vitreous at surgery.

• Eye shield, nil by mouth, tetanus prophylaxis, antiemetic, and urgent surgery within 24 hours.
• Systemic antibiotics: moxifloxacin 400 mg orally daily (or ciprofloxacin 750 mg twice daily) for 7 to 10 days, or IV vancomycin 1 g every 12 hours with ceftazidime 1 g every 8 hours; add clindamycin or metronidazole for organic foreign bodies; intravitreal antibiotics at surgery (vancomycin 1 mg in 0.1 mL and ceftazidime 2.25 mg in 0.1 mL, or moxifloxacin 0.1 mg in 0.1 mL) for contaminated or organic foreign bodies.
• Surgery: primary wound closure (corneal 10-0 nylon, scleral 8-0 or 9-0 suture) followed by foreign body removal, planned within 24 hours for organic or large lesions and in 7 to 14 days when delayed removal and vitreous detachment aids extraction in selected clean injuries:
  • Anterior chamber foreign body: removal with forceps or magnet through a limbal incision.
  • Lens foreign body: lensectomy.
  • Posterior segment: pars plana vitrectomy with removal of the foreign body (intraocular magnet for ferromagnetic fragments; forceps for non-magnetic), with tamponade (gas or silicone oil) and laser retinopexy as needed.
• Postoperative care: topical antibiotic four times daily, prednisolone acetate 1 percent every 2 to 4 hours, cycloplegia; oral prednisolone 1 mg/kg daily if marked inflammation; surveillance for retinal detachment, endophthalmitis, and proliferative vitreoretinopathy.
• Retained inert foreign bodies may be left in place; siderotic and copper foreign bodies should be removed.
• Prognosis: favourable with small anterior fragments and prompt care; poor with posterior location, large size, retinal injury, delay and endophthalmitis.
• Prevention: protective eyewear (polycarbonate safety goggles).