Foreign bodies
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Ocular foreign body refers to any external object lodged in the conjunctiva or cornea, leading to irritation, pain, or potential visual impairment.
Aetiology
- Metallic foreign bodies: common in industrial and construction settings.
- Organic foreign bodies: wood, plant material, or dust, carrying a higher risk of infection.
- Inorganic foreign bodies: glass, plastic, or sand particles.
- Projectile injuries: high-velocity particles from drilling, grinding, or explosions.
Pathophysiology
- Foreign bodies cause mechanical irritation, leading to reflex lacrimation and blepharospasm.
- Metallic particles may oxidise, forming rust rings that induce corneal toxicity.
- Organic material increases the risk of secondary infection and delayed healing.
Risk Factors
- Occupational exposure (e.g., construction, metalworking, woodworking).
- Failure to use protective eyewear.
- Outdoor activities in dusty or windy environments.
- Pre-existing ocular surface disease (e.g., dry eye, corneal dystrophy).
Signs and Symptoms
- Foreign body sensation: persistent irritation or discomfort.
- Excessive lacrimation: reflex tearing in response to irritation.
- Photophobia: increased light sensitivity.
- Redness: conjunctival hyperaemia around the affected area.
- Blurred vision: in cases where the visual axis is involved.
Investigations
- Slit-lamp examination: essential for identifying corneal or conjunctival foreign bodies.
- Fluorescein staining: detects epithelial defects and assesses corneal integrity.
- Eyelid eversion: examines the upper tarsal conjunctiva for hidden particles.
- Ocular X-ray or CT scan: indicated if intraocular penetration is suspected.
Management
1. Immediate Management:
- Topical anaesthesia: instilled before examination and removal.
- Saline irrigation: used to flush out superficial foreign material.
- Foreign body removal: with moistened cotton swab or sterile needle under magnification.
- Rust ring removal: corneal burr or referral if extensive.
2. Medical Management:
- Topical antibiotics: prophylactic chloramphenicol or fusidic acid to prevent infection.
- Lubricating eye drops: promote corneal healing and relieve discomfort.
- Analgesia: oral NSAIDs or paracetamol for pain relief.
3. Referral:
- Ophthalmology: indicated for deep-seated, intraocular, or recurrent foreign bodies.
- Emergency referral: if globe perforation or endophthalmitis is suspected.