What is a Rust Ring and How Do You Remove It?

Have I mentioned before that I hate treating ophthalmology problems? Well, that and testicular diagnoses. In each case, the patient only has two of the particular body part and the stakes are, needless to say, high when it comes to getting the right diagnosis. Diagnosing and treating eye related problems doesn’t give me quite the amount of anxiety it once did now that I am more seasoned in my practice. So, I do enjoy treating the occasional ocular foreign body- as long as I can successfully remove it, that is.

When it comes to eye health, it’s important that we as nurse practitioners and physician assistants have a solid foundation in our diagnostic and exam skills. Eye problems can range from simple infections and irritation to vision-threatening complications. Today, let’s talk corneal foreign bodies and rust rings.

What is a Corneal Foreign Body?

Small particles that make contact with the eye may become embedded in the cornea. this is commonly seen, for example, when metallic fragments fly into the eyes of construction workers or welders.

Foreign bodies in the eye result in abrasions to the cornea and are quite painful and irritating. Symptoms include redness, tearing, a foreign body sensation, pain, and/or blurred vision.

How Do You Remove a Corneal Foreign Body?

To examen a patient with a suspected corneal foreign body, and remove the offending particle follow these steps:

1. Apply anesthetic drops such as proparacaine to the affected eye.
2. Check the patient’s visual acuity.
3. Visualize the foreign body using a penlight. Don’t forget to check for foreign bodies under the eyelid by everting them completely. Remember, just because you see one foreign body does not mean there isn’t another.
4. Attempt to remove the foreign body by flushing the eye with normal saline.
5. If removal by flushing the eye is unsuccessful, then attempt removal using a moist cotton swab.
6. For more adherent foreign bodies, removal with an 18 to 30 gauge needle can be attempted. Don’t do this unless you are experienced. Bracing your hand against the patient’s face and using a slit lamp to guide you, flick the foreign body out of the eye with the needle. A dental burr can also be used to remove a foreign body from the eye however many ophthalmologists caution against this method due to the potential to cause significant damage to the eye.
7. Re-examen the eye, possibly even with fluorescein stain to make sure you have completely removed the foreign body.
8. If you are unable to remove the foreign body, patch the eye and refer the patient, ideally the same day, to an ophthalmologist.
9. Don’t forget to update the patient’s tetanus immunization if necessary.

What is a Rust Ring?

A rust ring may form around foreign bodies that contain iron, typically those that are metallic. The salt in tears interacts with the iron in the metal forming rust in the eye just like you see with metal left outdoors in the elements. The reaction begins within 2 to 4 hours of the foreign body embedding in the eye. Complete rust ring formation can be after about 8 hours. The rust ring may persist even after the foreign body is removed leaving a stain on the cornea. Many times the residual rust will migrate to the surface of the eye itself, usually within 24 hours. The American Academy of Ophthalmology recommends against attempting to remove a residual rust ring due to the possibility of doing further damage to the eye. 

How Do You Remove a Rust Ring?

While most ophthalmologists recommend that you leave rust ring removal to the experts, some experienced healthcare providers still take on the task themselves. Rust rings are removed using a rotating, sterile burr. These are available in most emergency departments. 

Again, rust ring removal should only be performed by an experienced provider as it carries a risk for complications including vision loss. 

To Patch or Not to Patch? Corneal Foreign Body Discharge Care

If you have successfully removed a foreign body from the patient’s eye, applying a patch is not necessary. There is no evidence showing that applying a patch speeds healing. In fact, patching may even do more harm than good. Make sure to prescribe prophylactic antibiotic drops or ointment to prevent infection. Corneal foreign bodies can be quite painful and some patients may require a prescription for narcotic pain relievers. Contact lens wearers should switch to glasses until healing of the eye is complete. Patients should follow up within 24 hours, ideally with an ophthalmologist, to monitor for proper ocular healing.