OP4.9 | Corneal Foreign Body Identification and Simulated Removal — Summary & Reflection

KEY TAKEAWAYS

Corneal foreign body management: initial assessment must include visual acuity, slit-lamp depth assessment (optical section), and the Seidel test to exclude perforation before any removal attempt.

Superficial FB (epithelium/Bowman's/anterior stroma, negative Seidel): remove at slit-lamp under topical anaesthesia (proparacaine 0.5% or benoxinate 0.4%) using a 23-gauge needle bevel-up at a tangential angle. Tangential approach = parallel to the corneal surface to minimise perforation risk.

Rust ring (from iron/steel FB): defer removal 24-48 hours to allow softening; use Alger brush or sequential needle debridement at follow-up; complete removal at one sitting is not mandatory.

Post-removal care: topical antibiotic (ciprofloxacin 0.3% or moxifloxacin 0.5% QID); cycloplegic for ciliary spasm; oral analgesics. Topical anaesthetics must NOT be prescribed for home use — epitheliotoxic and masks warning pain.

Vegetative FB: remove, then monitor for 2 weeks for fungal keratitis (feathery margins, satellite lesions → natamycin 5% hourly + refer).

Deep FB, positive Seidel, or intraocular FB: do NOT attempt slit-lamp removal. Shield the eye, nil-by-mouth, urgent surgical referral.

REFLECT

Corneal foreign body removal is a procedure you will likely perform hundreds of times in your career, particularly if you work in a rural or semi-urban setting with an agricultural population. Reflect: what is the most dangerous error you could make in this procedure (answer: attempting to remove a penetrating FB at the slit-lamp without doing a Seidel test first — potentially expelling intraocular contents). How would you build the Seidel test habit so reflexively that you never skip it, even when the patient is insisting you 'just quickly take it out'? What would you say to a patient who insists on taking the topical anaesthetic home with them?