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Corneal rust rings occur commonly when metallic foreign bodies become embedded in the cornea. Removal of the rust ring is imperative to avoid permanent staining of the cornea, persistent inflammation, or disruption of corneal integrity (necrosis) with loss of stromal substance.1–3 Two techniques for the removal of rust rings are discussed: hypodermic needle extraction and corneal burr drill removal. The use of topical deferoxamine as a chemical chelator is mentioned only for the sake of completeness.

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The cornea is approximately 0.5 mm thick. It is comprised of five layers (from outer to inner layer): epithelium, Bowman’s membrane, stroma (largest layer), Descemet’s membrane, and the endothelial layer which lies directly over the anterior chamber. Corneal rust rings are formed from the oxidation of iron present in metallic foreign bodies. As little as 3 hours of corneal contact are required to form the brown stain of a rust ring.1

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All corneal metallic foreign bodies require prompt removal to avoid the possibility of rust ring formation. A rust ring requires complete removal in a timely fashion in order to avoid the damaging effects of rust on the cornea.

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Corneal foreign bodies and rust rings that are located in the direct axis of vision can cause permanent visual disturbances if improperly removed.2 Consult an Ophthalmologist before removing these, as they often prefer to remove them. Do not attempt to extract a rust ring if the patient is confused or uncooperative as this can result in a perforated globe. Consider the use of intravenous sedation, procedural sedation, or general anesthesia to extract the rust ring.

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  • Slit lamp
  • 25 or 27 gauge needle
  • Tuberculin syringe with a needle
  • Burr drill
  • Burr bits
  • Topical ocular anesthetic agent
  • Topical ophthalmic antibiotic
  • Cycloplegic agents
  • Ringer’s lactate solution or normal saline

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Explain the procedure, its risks, and benefits to the patient and/or their representative. Obtained a signed informed consent to perform this procedure. Apply a topical ocular anesthetic agent into the affected eye. Determine the patient’s visual acuity in the affected eye. Seat the patient at the slit lamp with their head firmly in place to avoid any unexpected movement (Figure 137-1). Examine the eye via the slit lamp and rule out the possibility of an intraocular foreign body with a corneal perforation. Perform a complete eye examination to rule out any other ocular problems. Remove the foreign body, if still present, with the hypodermic needle or tuberculin syringe. Refer to Chapter 136 for the complete details regarding corneal foreign body removal. The rust ring will often be removed simultaneously with the metallic foreign body. Make an attempt to remove the rust ring if it remains after removal of the foreign body.

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Figure 137-1
Graphic Jump Location

Positioning of the patient and the examiner’s hand.

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Manual Technique

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