Foreign Body - Scope Connect

Introduction

A superficial ocular foreign body refers to an external object present on the surface of the eye, whether it’s on the conjunctiva, under the eyelid, or on the cornea. Corneal foreign bodies are the second most common form of eye injury,¹ following corneal abrasions. While significant loss of vision is rare, these foreign bodies are typically superficial and harmless, causing discomfort. Common symptoms include pain, redness, tearing, and a sensation of something in the eye. It’s important for patients to seek prompt and appropriate treatment to avoid complications like corneal abrasions or infections. Initial steps may involve clinicians trying to rinse out the foreign body with saline solution or artificial tears. If removal is unsuccessful or if there’s suspicion of a deeper object, seeking further assistance promptly is vital. Delaying treatment may lead to corneal damage and potential long-term issues such as scarring and vision loss.²

An intraocular foreign body refers to a foreign object that has entered the eye and is located within its structures Potentially this can pose a significant threat to vision and ocular health. Intraocular foreign bodies (IOFB) are observed in a substantial proportion of penetrating ocular injuries, estimated to be between 17-40%, and accounting for a notable portion (3%) of emergency room visits in the United States.³ Diagnosis relies on a comprehensive ocular examination, imaging studies, and a thorough patient history. Immediate medical intervention is essential to prevent complications such as infection, inflammation, or damage to the retina. Treatment typically involves surgically removing the foreign body and addressing any associated ocular injuries, aiming to preserve visual function and prevent long-term issues.

Clinical Evaluation

Risk Factors

Superficial foreign bodies often occur due to exposure to dust, debris, or other particles.
Conjunctival foreign bodies are common and can be successfully removed using suitable methods. Wearing protective eyewear, particularly in environments prone to debris, can effectively prevent superficial ocular foreign bodies.

Factors contributing to the risk of IOFBs include engagement in metal tasks, lack of eye protection, and being male.³ Importantly, IOFBs can penetrate the posterior segment of the eye.

Signs

Presence of a foreign body adherent to the ocular surface
Linear corneal scratches, particularly common with sub-tarsal foreign bodies
Corneal rust ring formation indicative of an embedded ferrous foreign body
Surrounding ring of oedema and infiltrate if the foreign body has been present for an extended duration
Possible presence of subconjunctival haemorrhage

Symptoms

Typically affects one eye
Foreign body sensation
Watering
Pain
Photophobia
Blurred vision
Red eye
Flashes or floaters
Some patients may have no apparent symptoms

Foreign bodies are often described as grit, debris, sand, or glass. Patients may have difficulty identifying the precise location of this sensation. Any discomfort is usually heightened during blinking, particularly when the foreign body is located on the inner conjunctival surface of the upper lid.

Differential Diagnoses

When faced with a patient with a painful red eye and a foreign body sensation clinicians may also wish to consider other potential causes:⁴

Corneal abrasion or laceration
Globe perforation or rupture
Intraocular foreign body
Retinal or vitreous issues like detachment or haemorrhage
Uveitis
Iritis
Endophthalmitis
Ultraviolet keratitis
Exposure-related issues
Chemical injuries
Infectious causes such as corneal ulcers, herpes zoster ophthalmicus, herpes simplex keratoconjunctivitis, or other viral or bacterial conjunctivitis

Investigations

Clinicians should consider the possibility of a foreign body if a patient complains of feeling something in their eye. A detailed history is a good starting point to help guide the clinician followed by an assessment of vision/ visual acuity for medico legal reasons. Next the clinician may conduct a thorough slit lamp examination with fluorescein helping to aid visibility.

To check for foreign bodies in the eye clinicians could consider some or all the following:

Examine the bulbar conjunctiva overlying the sclera
Patient to look up, down, left, and right, and the clinician looks for any redness indicating a conjunctival foreign body
Subsequently, inspect the inferior conjunctival fornix by having the patient look up while pulling down the lower lid
When it comes to the upper conjunctiva, clinicians may wish to perform upper lid eversion to examine the conjunctival surface inside the upper lid

When dealing with a corneal foreign body, a comprehensive history does help to guide the clinician provide appropriate care for their patients. Clinicians may consider asking questions about the type, timing, location, and circumstances of the incident. The material involved matters; for instance, iron can lead to a rust ring within hours. Understanding the injury mechanism can help the clinician to assess force, potential corneal perforation, and the possibility of extra tests such as ultrasound or CT scans. Tetanus prophylaxis may be necessary.

In intraocular foreign body (IOFB) injuries, again a detailed history should be considered to understand the foreign body’s type, material, and the injury mechanism.5 Clinicians may ask whether the injury is unilateral or bilateral as explosives and firearms often lead to bilateral ocular damage with multiple foreign bodies.

When examining a patient for potential penetrating ocular injuries clinicians may consider carrying out the following checks:

Visual acuity
Pupillary responses, pupil shape, afferent pupillary defect, or anisocoria
If a ruptured globe is suspected, pressure-inducing techniques like applanation tonometry are generally avoided
Examination of eyebrows/lids to check for
- Lacerations
- Canalicular injury
- Small foreign bodies
A full slit lamp examination helps identify
- Scleral or corneal entry sites
- Iris abnormalities
- Potential uveal tissue prolapse
Gonioscopy may be employed cautiously to assess the angles
Dilated fundus examination aids in posterior segment IOFB detection, paying attention to the peripheral retina

To fully localise IOFBs,⁶ further imaging techniques may be employed:

Historically, standard X-rays were used, but they are limited to radio-opaque foreign bodies
Metal locators, such as Berman, Roper-Hall, and Bronson-Turner, offer another method
Computerised tomography (CT) is the preferred imaging modality, providing detailed information on size, shape, and location
MRI should be avoided for metallic IOFBs due to the risk of dislodgement
Ultrasound may be useful, especially in open globe injuries, assisting in IOFB localisation and assessing intraocular damage
Ultrasonography, coupled with gonioscopy or ultrasound biomicroscopy, is valuable in challenging cases, but the clinician should take care to avoid intraocular content expulsion⁷

Other considerations for the clinician to bear in mind when interpreting a clinical history include:

High velocity particles – risk of globe penetration
Metallic (ferrous) – rust ring (haemosiderosis)
Vegetative – risk of fungal infection

Management & Advice

The following points provide the clinician with general guidance on how foreign bodies could be removed, but practitioners should consider their areas of confidence and competence and refer to colleagues if necessary (please refer to local guidelines for exact advice). Foreign bodies are normally removed by optometrists and ophthalmologists. Alternatively depending on location it may be carried out by suitably trained contact lens opticians or ophthalmic nurse practitioners.

Non-Pharmacological and Pharmacological Management/Treatments:

Conjunctival foreign body:⁸

For conjunctival foreign bodies, gentle removal can be achieved by wiping the affected area with a saline-moistened cotton swab^9,10
If the foreign body isn’t visible on the swab, saline irrigation may be attempted
If the patient experiences discomfort hindering these procedures, topical ophthalmic anaesthetic can be administered to facilitate examination and treatment
After applying topical ophthalmic anaesthetic, the clinician can proceed to identify the foreign body or determine another cause for the sensation

After removing conjunctival foreign bodies, clinicians should consider further careful examination to ensure it has been fully removed. Depending on local guidance, clinicians may consider prescribing broad-spectrum topical ophthalmic antibiotic post removal if there is a risk of infection. It is usually prudent to ask the patient to return if symptoms recur or if pain, redness, or visual changes arise.

Corneal foreign body:

The following steps are generally recommended for those practitioners trained in corneal foreign body removal, but may vary based on local guidelines:

Most corneal foreign bodies may be effectively removed at the slit lamp to prevent infection, inflammation, scarring, and vision loss⁹
Timely removal should be considered to avoid deeper embedding, potentially leading to delayed corneal perforation
Glass or fiberglass foreign bodies in the stroma may be monitored if removal poses greater risk
Topical anaesthesia is applied, and a needle or forceps, chosen based on the foreign body type, is used at an oblique angle^9,11,12
Magnetic spuds or moist cotton-tipped applicators can aid in removal
Rust rings from metallic foreign bodies can be lifted, and post-removal, the cornea is reassessed for any residue or defects, with Seidel testing for deep defects

Again depending on local guidance patients with corneal foreign bodies may be prescribed broad-spectrum topical ophthalmic antibiotics for a week or until re-epithelialisation occurs. Short-term use of a therapeutic bandage contact lens is sometimes used to help reduce discomfort by acting as a barrier, minimizing shear forces, and promoting healing.¹² The clinician should consider follow-up evaluations at appropriate intervals to assess the epithelial defect, corneal oedema, or infection. Deeply embedded foreign bodies may lead to scars, impacting vision, astigmatism, and causing glare.

NOTE: Symptom relief should result from the clinician’s actions, not the anaesthetic. If doubt persists after using anaesthetic, wait at least 30 minutes for it to wear off, then reassess to ensure proper resolution. Successful removal of a conjunctival foreign body should result in no recurrent symptoms after the anaesthetic wears off.

Intraocular Foreign Body:

These will generally need a surgical approach⁶

The approach for intraocular foreign bodies (IOFB) hinges on determining their position relative to the iris
Initial stabilisation involves closing the open wound
If the IOFB is in the anterior chamber, a limbal incision is often utilised and viscoelastic solution safeguards the corneal endothelium and maintains the chamber during removal
Specialised techniques may be necessary for embedded FBs in the iris, ciliary body, or lens
Posterior chamber IOFBs are addressed with pars plana vitrectomy (PPV), and extraction technique varies based on object composition and size
Retinal tears and detachment, if present, can be treated with gas or oil tamponade
In the absence of tears or detachment, a tampon-adding agent may not be necessary
Depending on local protocols, intravitreal antibiotics may be considered for contaminated IOFBs

Prognosis

Early Detection and Removal: Prompt identification and removal of ocular foreign bodies improve prognosis.
Corneal Involvement: Superficial corneal foreign bodies usually have a good prognosis if promptly and properly managed, minimizing the risk of infection or complications.
Complications: The prognosis may be affected by the nature of the foreign body, its location, and any associated complications like infection or corneal abrasions.
Medical Attention: Seeking timely medical attention and appropriate treatment is crucial for a favourable prognosis, preventing potential long-term damage or vision impairment.
Prevention: Advising patients to adhere to safety measures, as well as emphasising the importance of preventive strategies for overall eye health, particularly eye protection in occupational and domestic settings can help to reduce the incidence of penetrating ocular injuries and their associated risks

This article serves as an overview of the condition and treatment options. It does not serve as a clinical guidance. Eyecare provider guidelines should be used when managing patients.