32 year old male presents with a right sore and irritated eye upon blinking. He reports the symptoms after using a grinding machine at work ~1 week ago.
What is the cause?
Answer: Rust ring due to a metallic foreign body
Ferrous particles in situ for even a few hours can cause rust staining of the bed of the abrasion.
Removal of a rust ring is performed by:
1. Instil 1 drop of topical anaesthetic (e.g Alcaine, Oxybuprocaine eyedrops)
2. Determine the position and depth of rust ring with a slit lamp.
3. Use a sterile 25 gauge needle or a sterile burr to removal the rust ring.
4. Prescribe topical antibiotic for prophylactic cover and lubricants to promote corneal healing.
If a corneal foreign body is not removed, there is a significant risk of secondary infection and corneal ulceration.