A corneal foreign body is an object either superficially adherent or embedded in the cornea of the eye. The removal of foreign body from Cornea is a procedure which is commonly performed in the clinic or emergency department setting.
If foreign body from cornea is not removed in a timely manner, they can cause prolonged pain and lead to complications such as infection and ocular necrosis.
An intraocular foreign body penetrates into the anterior chamber of the eye or into the globe itself. It is likely to cause significant morbidity and, thus, necessitates a thorough workup, including, in many instances, a detailed ophthalmologic evaluation with imaging such as plain radiography or CT scan of the orbits.
Though MRI is occasionally used, it is contraindicated if a metal foreign body is suspected. The patient’s description of the circumstances of the injury is the most crucial element in determining the likelihood of globe penetration. An intraocular foreign body does not necessarily change visual acuity.
Removal of foreign body from Cornea is indicated when a foreign body is present on the cornea.
Anesthesia is necessary prior to the removal of foreign body from Cornea and usually facilitates the initial eye examination.
Instill a topical anesthetic ophthalmic solution (e.g., proparacaine 0.5% Alcaine, Ophthetic).
Equipment used for removal of foreign body from Cornea includes the following:
- Topical anesthetic ophthalmic solution (e.g., proparacaine 0.5% Alcaine, Ophthetic)
- Fluorescein strips
- Cotton-tipped applicator
- Irrigation fluid with a plastic syringe
- Have the patient press his or her face against the forehead strap and chin rest as demonstrated below so that the patient cannot move his head (and, hence, eye) forward toward the eye spud or needle during removal of the foreign body. This positioning is critically important.
- The clinician’s hand should be similarly anchored, either against the patient's face or on part of the slit lamp itself. Again, this prevents the clinician from inadvertently penetrating the patient's cornea with the spud or needle during the procedure.
- When removing an object from the left eye, place the hand on the left maxillary bone.
- When removing an object from the right eye, place the hand against the bridge of the nose or the infranasal aspect of the face.
The technique is as follows:
- Place 2 drops of anesthetic ophthalmic solution inside the lower eyelid.
- Apply a wet fluorescein strip inside the lower eyelid to instill fluorescein onto the cornea. Under ultraviolet light, examine the cornea to locate the foreign body. Document a negative Seidel sign. (A positive Seidel sign indicates corneal penetration with oozing aqueous humor it appears under ultraviolet light as a "dark waterfall," clearing away excess fluorescein on the cornea.)
- Inspect the lower eyelid while the patient looks up.
- Inspect the upper eyelid by everting with an applicator while the patient looks down. Sweep the recesses of the upper conjunctival fornix.
- If the foreign body is superficial, irrigate the eye to moisten the cornea and attempt to remove the foreign body by using a gentle rolling motion with a wetted cotton-tipped applicator. Take care not to apply pressure, which may push the foreign body deeper into the cornea, or scrape, which may create a large corneal abrasion.
- An embedded foreign body cannot be removed with irrigation or with a cotton-tipped applicator.
- An embedded foreign body can be removed by using a gentle flicking motion with an eye spud, if available, or with a 25- or 27-gauge needle. Place the hub of the needle on the tip of a cotton swab or a 3-mL syringe. Approach the cornea from the side, with the needle in a plane tangent to the cornea and the bevel away from the corneal surface. This minimizes the chance of corneal perforation. Once dislodged from its embedded position on the cornea, remaining corneal debris can be removed with a wetted cotton-tipped applicator.
- Document a negative Seidel sign after the foreign body is removed.
Potential complications of corneal foreign body removal include the following:
- Incomplete foreign body removal or rust ring
- Perforation of the cornea
- Epithelial injury