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Removal of Superficial Corneal Foreign Bodies

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Title: Removal of Superficial Corneal Foreign Bodies
Author: Austin D. Bohner, MS3 University of Utah
Photographer: James Gilman, CRA, FOPS; Ethan Peterson; Melissa Chandler; Mary Mayfield
Date: 01/08/19
Keywords/Main Subjects: Cornea, Foreign Body
Diagnosis: Superficial Corneal Foreign Body

Images:

Figure 1: Deep corneal injury with penetration into the anterior chamber. Also observe dense cataract and iris distortion.

 

Figure 2. Post-removal and repair of deep penetrating corneal foreign body with anterior chamber perforation. The repair was performed in a sterile operating room under general anesthesia. Simple interrupted sutures using 10-0 monofilament were placed to close globe penetration with the goal of preventing leak and anterior chamber collapse.

 

Figure 3. Retoillumination of corneal foreign body.

 

Figure 4. Corneal burr used along the tangential plane.

 

Figure 5. Highly magnified corneal burr tip.

 

Figure 6. Corneal burr and tip, held to display tip size and holding position.

 

Clinical Identification and Management:

Superficial corneal foreign bodies (SCFB) are easily seen and usually can be removed in clinic or the ED with minimal or no long term complications.1 SCFB are best identified through slit lamp microscopy. The source of the SCFB is often revealed through patient history and allows clinicians to assess the risk of infection after removal of the material.1 Metals are common SCFB culprits and are often seen in malleolus workers at risk for high-speed metallic particles lodging in the eye.2 Activities with the highest associated risk of SCFB include high-speed metal grinding and metal-on-metal hammering.2 It is recommended that workers engaging in these risky activities utilize eye glass protection for SCFB prevention.

Trained clinicians can easily remove SCFB. Before attempting to remove a SCFB, however, the clinician should first assess the depth of penetration and rule out a ruptured globe or intraocular foreign body.3 Particles penetrating beyond bowman’s layer will result in some degree of corneal scarring. Deep corneal infiltration or penetration of the anterior chamber (Figure 1) may warrant utilization of a different removal technique. In the case of a full thickness corneal laceration the eye should be shielded and no manipulation of the cornea attempted until the patient paralyzed and sedated under anesthesia, for risk of expulsing intraocular contents. Full thickness corneal lacerations may require the use of corneal sutures in order to secure the globe and prevent anterior chamber collapse (Figure 2.)

When treating a superficially lodged corneal foreign body, adequate topical anesthesia with ophthalmic eye drops (such as proparacaine) is imperative. Removal of SCFB should be performed using a slit lamp for visualization. Retoillumination with slit lamp microscopy can be used to visualize a small corneal foreign body (Figure 3.) The patient should be instructed to fix their gaze straight ahead and focus on a specific target, such as a far-away point or the clinician’s ear. The patient’s forehead should be pressed completely against the forehead plate of the slit lamp to optimize stabilization during SCFB removal. During the procedure, it is recommended to adjust the light source to being bright enough to clearly visual the cornea but dim enough to be tolerable to the patient.  Removal of the SCFB can be achieved using a 25-30 gauge, sterile, disposable, hypodermic needle. The clinician should operate the slit lamp with one hand, using the other hand to hold the needle and manipulate the eyelid if necessary. When using the needle, always approach the cornea in a tangential plane and never in perpendicular alignment, as it is likely to intensify patient anxiety and increase the risk of inadvertent corneal perforation. In the tangential plane, with the bevel facing away from the corneal, the SCFB can be gently scraped away. A rust ring is commonly seen after removal of iron-containing SCFBs. The remaining rust ring can be carefully scrapped away with any additional ring remains self-resolving by reabsorption over time.

Removal can also be achieved through use of a battery-powered dental burr, similar to a Dremel drill (Figures 4-6). The battery-powered dental burr can be used as a complimentary removal tool to the hypodermic needle. In some instances the burr may be used in lieu of a hypodermic needle, depending on clinician preference. Prior to use, the burr tip should be sterilized in a standard fashion. Similar to the hypodermal needle, burr tip should be used in a tangential corneal plane.

Topical antibiotics are recommended for all patients following removal of the SCFB.2,3 Furthermore, dilating eye drops (such as 1% cyclopentolate or atropine) and the use of a contact bandage lens can be useful for some patients. Patients should be monitored for signs of infection with close follow-up.

Faculty Approval by: Griffin Jardine, MD

References:

  1. Wipperman JL, Dorsch JN. Evaluation and management of corneal abrasions. Am Fam Physician. 2013;87(2):114-120.
  2. DeBroff BM, Donahue SP, Caputo BJ, Azar MJ, Kowalski RP, Karenchak LM. Clinical characteristics of corneal foreign bodies and their associated culture results. CLAO J. 1994;20(2):128-130.
  3. Ophthalmology AAo. 2015-2016 BCSC (Basic and Clinical Science Course). In: External Eye Disease and the Cornea. American Academy of Ophthalmology; 2015:355-356.

Identifier: Moran_CORE_26928

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