Corneal foreign body (CFB) is a common ophthalmic presentation to the Emergency Department (EDs). Removal is facilitated by gentle mechanical displacement of the foreign body in the anesthetized cornea. Confidence in performing this procedure varies between trainees and physicians depending on training and exposure, though research has revealed that approximately 70% of emergency doctors lack confidence in dealing with ocular emergency presentations.[1,2] With reports that 84% of the Australian ophthalmology workforce reside in metropolitan areas, a difficult CFB removal can be isolating for a remote medical practitioner with limited ophthalmic support. This letter aims to provide useful tips and tricks beyond clinical practice guidelines for emergency medicine trainees, rural practitioners, and physicians undertaking a CFB and rust ring removal with limited access to an ophthalmology service.
Initially, a thorough history and slit lamp eye examination are required to ensure that a penetrating eye injury is excluded. After the exclusion, eyelid eversion is important to ensure that no debris remains hidden behind the eyelids. A topical anesthetic agent is required to ensure that the eye is comfortable prior to the procedure. This may need to be repeated before or during the procedure as the effectiveness of the anesthetic agent may be reduced given several factors. This can be due to increased conjunctival injection as the anesthetic agent is quickly absorbed systemically thus reducing its residence time and effectiveness. Additionally, a patient squeezing their eyes shut can displace a significant proportion of the instilled topical agent.
In terms of patient setup, the examination room lights should be dimmed to ensure patient comfort and facilitate their ability to keep their eyes open during the procedure. Patients should be instructed to focus on a target to keep the eye steady.
In situations of a nasal foreign body or where access to the cornea is challenging, the patient's face can be carefully positioned on the slit lamp in such a way that facilitates access. This can include head rotation or tilting. Usually, in combination with directing gaze on a suitable target, access can be improved significantly.
Occasionally the CFB may be superficial and can be removed with a moistened sterile cotton tip or irrigation, though if firmly embedded a needle may be required. Needle sizes may range from smaller 30G to larger 21G needles. Differing sizes of the needle tip may provide different leveraging forces in removing the CFB. Mounting the needle on a syringe provides good stability and control during the foreign body removal process compared to an unmounted needle. The needle base may be bent to facilitate a parallel orientation of the needle tip to the corneal surface. Approach horizontally from the periphery with the bevel facing outwards. Gently use the needle to lift the foreign body from the cornea, ensuring that all remnants are removed.
The electric burr is a common tool used for the removal of rust ring, but may not be available in all ED settings. To facilitate rust ring removal, the very tip of the needle may also be bent, so that it adopts a more perpendicular angle to the corneal surface to facilitate gentle scraping of the rust ring.
During this process, the practitioner should have part of their hand or fingers braced against part of the patient's face such as the forehead or orbital rim to avoid corneal trauma from sudden, unexpected patient movement during the procedure.
Chloramphenicol drops are typically prescribed on discharge. The ointment form may be considered to improve patient comfort and in situations of poor compliance given the increased residence time of the more viscous agent. Patients will have to be counseled regarding the greater effect of blurred vision in the use of ointments. Patients should be told to expect pain for 48 hours. Local anesthetic drops should never be given to the patient on discharge due to toxic effects that delay corneal healing and the potential to mask worsening pathology. Encourage cool eyelid compresses and oral analgesia on discharge. An optometrist follow-up should be considered where accessible.
Conflict of interest statement
The authors declare that they have no financial conflict of interest with regard to the content of this report.
Authors Wilson MM and Mathan JJ contributed to the design and implementation of the research and to the writing of the manuscript.
There was no funding received for this work.
Ethical approval of studies and informed consent
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