Clinical Update on the Removal of IOFBs

A comprehensive guide to diagnosis and treatment

ALEKSANDRA V. RACHITSKAYA, MD • JONATHAN S. CHANG, MD

Ocular trauma has a variety of presentations. It can be classified as open or closed globe injury. Although the term “ruptured globe” is used loosely to denote any type of open globe injury, the injury should be subclassified as a ruptured globe only when the impact is from blunt trauma and as a laceration when the impact is due to a sharp object.

The trauma resulting from laceration can be further classified as penetrating when there is only an entry wound and as perforating when there is both an entry and an exit wound.¹

An intraocular foreign body can be associated with penetrating or perforating injury and can involve the anterior chamber, crystalline lens, posterior chamber, and even the orbit if a posterior exit wound is present.

HISTORY

When a patient presents with an open globe injury, a complete history is essential in establishing a diagnostic and therapeutic plan and providing appropriate education and prognosis. Whenever possible, the witnesses should be involved to corroborate the story. Family should be involved to ensure the understanding of the management and the prognosis.

A physician should elicit the circumstances of the injury, including the activity that the patient was involved in, the use of protective eyewear, the time from injury to presentation, visual complaints, including decreased vision and pain, prior interventions, prior ocular and medical history, and the condition of the other eye.

It can be helpful to understand the material of which the possible IOFB consists. The physician should document whether the injury occurred at work or was due to an assault and whether a police report was filed.

Ocular trauma tends to happen in young men. IOFBs occur at higher rates in work-related injuries (35% of all work-related penetrating eye injuries), as compared to assault-related injuries (6% of all assault-related penetrating eye injuries).^2,3 In a study of occupational eye injuries, only 6% of patients with penetrating eye injuries were wearing protective eyewear and 3% nonprotective eyewear.²

CLINICAL EXAMINATION

First, any life-threatening injuries should be assessed and treated appropriately, particularly because of the risk of associated head trauma. A complete clinical examination of the unaffected eye should then be performed. In the affected eye, the physician him- or herself should check and document the visual acuity and relative afferent pupillary defect. It might be advisable to have a family member in the room, especially if the presenting visual acuity is poor.

The measurement of intraocular pressure should be deferred if there is a large laceration or concern for a ruptured globe. It is not uncommon that, in cases of small projectile foreign bodies, such as those associated with hammering, the entry wound is small and can be self-sealing (Figure 1).

Figure 1. Various IOFB entry wounds. A) A 47-year-old man was hit with a piece of wood while working. A large corneal-limbal laceration was repaired at an outside hospital. B) Following a CT scan confirming an IOFB, a 15-mm nail was removed through the entrance wound. C) A 47-year-old man was hit with a long piece of wire that caused a central corneal laceration and traumatic cataract. The IOFB protruded through the cornea and was removed through the entrance wound. D) A two-year-old girl without any complaints presented for a three-day history of eye redness. A small self-sealed corneal laceration and traumatic iridotomy are seen (arrow). A macula-involving IOFB was removed.

Both adult and pediatric patients may delay seeking care due to a lack of symptoms and might not even be aware that there is an IOFB present. Small children might not complain at all because small corneal epithelial defects heal rapidly, and the child switches to using the other eye.

At presentation, retrobulbar hemorrhage and fractures should be excluded. After examination of the ocular adnexa for laceration, bruising, and superficial foreign bodies and the conjunctiva for laceration, corneal and scleral defects should be documented, including Seidel testing.

The iris should be examined before dilation because an IOFB may create a small peripheral iridectomy, visible only with transillumination (Figure 1D). Evidence of inflammation, hypopyon, or hyphema should be documented. Pupillary dilation should be avoided if uveal tissue is incarcerated in a corneal laceration. Otherwise, the lens and posterior-segment status should be assessed with dilation.

With IOFBs, violation of the anterior and posterior lens capsule can be seen. However, sometimes only peripheral cataractous changes are observed, or the crystalline lens may be spared. The location of an IOFB should be assessed if possible to assist with visual prognosis and perioperative planning.

Vitreous hemorrhage can preclude visualization of the posterior-segment IOFB. An open globe with IOFB can be associated with retinal tears, retinal detachments, choroidal detachment, choroidal rupture, sclopetaria, and a posterior exit wound.

PREOPERATIVE CONSIDERATIONS

The exact details of open globe management, such as the choice of systemic antibiotics, vary between hospitals. The general principles of open globe management involve obtaining a tetanus immunization history and administering tetanus toxoid or tetanus immune globulin. A Fox shield should be applied.

Broad-spectrum systemic antibiotics, as well as topical antibiotics, should be administered. The patient should be placed on NPO status and bed rest with bathroom privileges in preparation for surgery. Any pain or nausea should be addressed, and the medical clearance for surgery should be obtained.

IMAGING

If an IOFB or head trauma is suspected, imaging should be performed, allowing for confirmation of the IOFB, as well as identification of its location and, to some degree, assessment of damage to other structures. MRI should be avoided in open globes given the concern of a ferromagnetic IOFB. Any head trauma requires evaluation by the appropriate services.

Computerized tomography scan is the most commonly utilized imaging modality. It is helpful to obtain thin (1 mm) cuts and coronal, axial, and sagittal views. However, studies have shown that, with modern spiral CT scanning, 3-mm cuts are as sensitive as 1-mm cuts for detecting 0.5-mm metallic, glass, and stone IOFBs.⁴ Metal, glass, and stone are most easily detected materials (Figure 2A). Plastics vary in their composition; thus, their CT appearance is variable. Wood can display a variety of CT appearances, depending on materials, types, coating, and time course, although it is usually hypodense and may be mistaken for air or fat.⁵ Additionally, a CT scan will rule out a fracture or any retrobulbar process.

Figure 2. Orbital, anterior-segment, and posterior-segment IOFB presentation and management. A) CT scan of the orbits, sagittal view, of a 13-year-old boy who suffered an injury due to a pellet gun. A perforating eye injury to the right eye with both entrance and exit wounds is visible on the scan, as well as the retained lead pellet in the orbit. B) Anterior-chamber IOFB (arrow) with involvement of anterior lens capsule. C) Encapsulated ferromagnetic IOFB of one month duration in a 16-year-old child from Honduras. D) Pars plana removal of a piece of wire wheel brush. A separate sclerotomy was created in this 23-gauge case, and the crystalline lens was spared.

Plain X-ray is not commonly utilized as a primary imaging modality but remains an option in cases in which there is no access to CT. Ultrasound biomicroscopy is not routinely used in the presence of an open globe given the risk of expulsion of intraocular contents. However, the modality is useful for localization of IOFBs, identification of occult IOFBs, and examination of associated intraocular pathology.⁶ Finally, although not widely available, a metal detector can be used to determine the presence of a metallic foreign body.

MANAGEMENT

Once the presence of the IOFB is confirmed, the intervention plan should be discussed with the patient and family. It is essential to discuss the prognosis, depending on the severity of the injury and resultant ocular damage. However, the determination of prognosis is difficult.

In the IOFB literature, the same variables that were found to be prognostic factors for final VA in some studies were found to bear no prognostic significance in others.⁷ It is important to explain upfront that many patients will also require multiple surgeries.

Timing

Historically, it was believed that a patient with an IOFB should be taken to the operating room as soon as possible and that delaying surgery by more than 24 hours from the injury could result in higher rates of endophthalmitis and proliferative vitreoretinopathy.⁸

A study from the Walter Reed Army Medical Center showed that delayed IOFB removal (median time to IOFB removal was 21 days), with a combination of systemic and topical antibiotic coverage, could result in good visual outcome without an apparent increased risk of endophthalmitis or other deleterious side effects. However, the cohort for this study consisted of soldiers in wartime conditions, so its applicability to day-to-day injuries is unknown.⁹

Anesthesia

General anesthesia has traditionally been used for open globe injuries. However, it has been shown that, in select cases of IOFBs, local anesthesia with sedation might be an option.¹⁰

Closure of the Entry Wound

While closure of the entry wound is usually the first step of surgical management, sometimes small, self-sealed corneal wounds can be closed at the end of the case because placing sutures might change corneal contour and hinder the view of the posterior segment.

In IOFB cases, the majority of entry wounds involve zones I and II (zone I is defined by the corneal limbus, zone II extends from the limbus to 5 mm posterior, and zone III is posterior to 5 mm from the limbus).^11,12

Corneal wounds are often closed with 10-0 Nylon sutures, and the sclera can be closed with 9-0 or 8-0 Nylon sutures. Keeping sutures buried or hidden under conjunctiva can improve postoperative comfort for the patient, even in an eye with limited visual potential.

ANTERIOR-CHAMBER IOFBS

Anterior-chamber IOFB without involvement of the crystalline lens can often be removed through an enlarged paracentesis wound. Viscoelastic can protect the corneal endothelium and crystalline lens as forceps are used to remove the foreign body.

Forceps designed for foreign body removal, such as Rappazzo forceps and straight forceps are available. For smaller IOFBs, 23-gauge serrated forceps may be sufficient.

LENTICULAR IOFBS

If an IOFB involves the lens, it is important to determine the posterior capsule status (Figure 2B). In some cases, IOFB removal with phacoemulsification can be performed without concurrent vitrectomy. It is advisable to perform such a surgery on a machine that allows for conversion to pars plana vitrectomy, if necessary.

Primary placement of an intraocular lens is a point of debate, especially in eyes with IOFBs.^13,14 Some argue that, in the absence of endophthalmitis, it is safe to place an implant that will result in more rapid visual rehabilitation with a single operation, reducing costs and patient discomfort. However, the lens calculations may be inaccurate due to the inability to measure axial length and perform keratometry. There is also a risk of traumatic endophthalmitis.

POSTERIOR-SEGMENT IOFBS

The posterior segment is most commonly involved in IOFB-related injuries (Figure 2C).¹⁵ An IOFB can be located in the vitreous, retina, subretinal space, or traverse posterior sclera. Today, the majority of surgeons prefer PPV to the use of an external electromagnet in the management of posterior-segment IOFB.⁷

The choice of instrument size for PPV is determined by the surgeon’s preference. Twenty-gauge vitrectomy can be performed, but posterior-segment IOFBs can also be removed using 23- or 25-gauge PPV.¹⁶

In cases of poor visualization of the infusion cannula due to choroidal detachment, vitreous hemorrhage, or lenticular opacity, a 6-mm infusion cannula or an anterior-chamber maintainer can be used.

Once a complete vitrectomy has been performed and the IOFB identified, removal can be performed through an existing sclerotomy or a separate pars plana sclerotomy (Figure 2D).

If the sclerotomy is large, sutures can be preplaced to assist with regaining IOP and to avoid expulsion of intraocular contents after the IOFB is removed. Large IOFBs sometimes require the creation of a scleral tunnel or clear corneal wound.

If the crystalline lens is intact, it does not have to be removed (Figure 2D). In fact, even in cases in which there are peripheral cataractous changes due to an IOFB, the lens can be preserved. It has been shown that the cataract does not necessarily progress rapidly, and lenticular opacity remains localized to an eccentric location.¹⁷ The lens can be removed either by phacoemulsification or via pars plana lensectomy.

The crystalline lens is removed when there is violation of the capsule, to aid in visualization of the posterior segment and in the removal of the IOFB. If the capsule is violated, complete lens removal may also reduce postoperative inflammation.

Posterior-segment IOFB Removal

After a complete PPV and generation of posterior vitreous detachment, the IOFB is localized and freed. Overlying membranes or scar tissue may need to be removed. The IOFB can be grasped with forceps or a magnet and removed through the sclerotomy, scleral tunnel, or corneal wound.

The handshake maneuver involves passing the IOFB from one instrument to the other inside the eye, and it is usually reserved for aphakic or pseudophakic patients and can require the use of the chandelier. If the likelihood of IOFB slippage is high, perfluorocarbon liquid can be used to protect the macula and allow the IOFB to float anteriorly.

There is a variety of instrumentation to remove an IOFB depending on the size, shape, and ferromagnetic properties. The Wilson, Machemer, basket, and Rappazzo forceps are among the reusable instruments employed, but they are not widely available. Rather, straight diamond-dusted forceps are the most commonly utilized. Some internal magnets can be retractable. A range of disposable instruments may also be available for IOFB removal. Removal of a BB pellet is challenging and requires modified forceps.

Once an IOFB is removed, a thorough peripheral retinal exam should be performed. If the IOFB was embedded in the retina, laser demarcation of the defect might be required and may be performed prior to removal of the foreign body. Any tears, breaks, or retinal detachments should be treated. If tamponade is required, air, gas, or silicone oil may all be used safely.

ENDOPHTHALMITIS

If endophthalmitis is present at the time of surgery, it should be addressed by performing undiluted or semidiluted vitreous cultures and by sending the vitrectomy cassette to microbiology. Intravitreal injections of broad-spectrum antibiotics, such as vancomycin and ceftazidime, are performed.

If the injury is due to organic matter, antifungals can be considered. If the surgery is performed during daytime hours, a rapid Gram stain can be obtained. Silicone oil can be considered as a tamponade.¹⁸

If there is no evidence of endophthalmitis, a surgeon should consider administering intravitreal or intracameral injections. Intraocular injections have been shown to decrease the rate of traumatic endophthalmitis.¹⁹

TYPES OF IOFBS

Metallic IOFBs are by far the most common, followed by glass or wood. Not all IOFBs need to be removed. Glass IOFBs constitute 6% to 9% of all IOFBs.²⁰ If there is no structural damage, glass IOFBs can be observed. Retained metallic IOFBs, in contrast, can result in chalcosis and siderosis.

POSTOPERATIVE CONSIDERATIONS

Patients treated for IOFB should be followed closely in the postoperative period due to the high risk of such complications as endophthalmitis, retinal detachment, PVR, and cataract formation. With metallic IOFBs, which are the most common, it is estimated that 40% of patients require secondary interventions, including surgery for retinal detachment or cataract.¹¹

CONCLUSION

Intraocular foreign bodies are challenging for both patients and vitreoretinal specialists due to the high risks of morbidity and prolonged care. The variety of presentations, including the type of IOFB, size, location, and coexisting ocular pathology, require good patient education and solid diagnostic and therapeutic approaches. With timely management, select cases may have good visual outcomes. RP

REFERENCES