Intraocular Foreign Body (IOFB) 

Updated: May 18, 2017
Author: Ferenc Kuhn, MD, PhD; Chief Editor: Inci Irak Dersu, MD, MPH 

Overview

Background

Intraocular foreign bodies (IOFBs) are rather variable in presentation, outcome, and prognosis. With increased awareness and advanced surgical techniques, the outcome and the prognosis for these potentially devastating injuries have substantially improved.

The most important limiting factor today is the damage occurring at the time of the initial injury. One effective method appears to be prophylactic chorioretinectomy (see Surgical Care), which reduces the risk of postinjury proliferative vitreoretinopathy (PVR).

Metal intraocular foreign body located in the left Metal intraocular foreign body located in the left temporal pars plana region seen on axial CT scan.

Pathophysiology

The final resting place of and damage caused by an IOFB depend on several factors, including the size, the shape, and the momentum of the object at the time of impact, as well as the site of ocular penetration.[1, 2]

IOFBs transversing the lens are less likely to cause major retinal damage; conversely, a smaller wound size usually means deeper penetration.

In addition to the initial damage caused at the time of impact, the risk of endophthalmitis and subsequent scarring (eg, PVR) play an important role in the planning of the surgical intervention.[3]

Epidemiology

Frequency

United States

According to the United States Eye Injury Registry (USEIR), the surveillance arm of the American Society of Ocular Trauma (ASOT), the incidence among eyes with open-globe injury is 16% in the United States. The most common cause is hammering; the incidence over time shows a decrease at the workplace and an increase in the home.[4]

International

The frequency greatly varies (up to 41%) worldwide, depending upon the population surveyed.

Mortality/Morbidity

Most IOFBs cause internal damage, and most will come to rest in the posterior segment. Commonly injured structures include the cornea, the lens, and the retina.

Race

No racial predilection has been found so far.

Sex

According to the USEIR, 93% of patients with IOFBs are male.

Age

According to the USEIR, the average patient is aged 31 years.

 

Presentation

History

A few direct questions should be sufficient for the ophthalmologist to suspect the presence of an IOFB in eyes with an open globe injury.

In case of doubt, it is advisable to err on the side of an IOFB presence. The most common cause for litigation against the ophthalmologist in a trauma case is a missed IOFB. It is important to remember that the patient may be unaware of any object entering (or even striking) the eye, and the vision may be unaffected initially.

Physical

A complete examination of both eyes is necessary, including the visual acuity.

A corneal entry wound and a hole in the iris provide trajectory information.

The slit lamp is extremely useful in detailing all anterior segment pathologies.[5]

The indirect ophthalmoscope through a dilated pupil may allow direct visualization of the IOFB, which gives the most useful information for the surgeon.

Gonioscopy and scleral depression are not recommended unless the entry wound has been surgically closed.

Causes

Hammering and using power tools are the most important causes. Protective eyewear, if appropriate (3 mm of polycarbonate), prevents virtually all injuries.

 

DDx

Differential Diagnoses

 

Workup

Laboratory Studies

Culture an intraocular foreign body (IOFB) or a sample of vitreous if an infection is suspected. Remember that a positive result does not mean that an infection is occurring and that a negative result does not preclude the possibility of endophthalmitis.[6]

Imaging Studies

CT scans are the imaging study of choice for IOFB localization. A consultation with the CT technician is helpful in selecting the optimal section so as to reduce the risk of a false-negative result. A helical CT scan is the most efficient method to establish a diagnosis. Helical CT scans have a very high identification rate. With conventional CT scans, cuts of 0.5 mm are advised.

Metal intraocular foreign body located in the left Metal intraocular foreign body located in the left temporal pars plana region seen on axial CT scan.
Same metallic intraocular foreign body as in previ Same metallic intraocular foreign body as in previous image, as seen on coronal CT scan view.

Plain x-ray is useful if a metallic IOFB is present and a CT scan is unavailable.

MRI is generally not recommended for metallic IOFBs.

Ultrasound is a useful tool in localizing IOFBs, and its careful use is possible even if the globe is still open; alternatively, intraoperative use after wound closure can be attempted. The ultrasound biomicroscope may help with IOFBs in the anterior segment.[7, 8]

Other Tests

Electroretinography is useful if a chronic IOFB is found and siderosis threatens or is present.

 

Treatment

Medical Care

Systemic and topical antibiotic therapy may be started prior to the surgical intervention. Topical corticosteroids are also important to minimize the inflammation. A tetanus booster may also be appropriate.

Surgical Care

The timing of intervention is primarily determined by whether the risk of endophthalmitis is high. If the risk is high, immediate (emergency) surgery, for intraocular foreign body (IOFB) removal as well as vitrectomy if the IOFB is in the posterior segment, is indicated.[9] In most other cases, the surgeon has the option of deferring intervention for a few days to reduce the risk of intraoperative hemorrhage. The wound, however, should be closed as soon as possible. A study by Zhang et al examined 1421 eyes in 15 hospitals in China over 5 years and concluded that closing the primary wound within 24 hours, whether by repair or independent self-sealing, reduces the endophthalmitis risk.[10] If endophthalmitis occurs, it is present at the time of patient presentation in over 90% of the cases.[11, 12]

IOFBs in the anterior chamber are typically removed through a paracentesis (not through the original wound) performed at 90-180° from where the IOFB is located. Viscoelastics should be used to reduce the risk of iatrogenic damage to the corneal endothelium and the lens.

An intralenticular IOFB does not necessarily cause cataract. Unless there is a risk of siderosis or the loss to follow-up is high, the IOFB and the lens may be left in situ. Otherwise, usually, the IOFB is extracted first, the lens is extracted second, and an intraocular lens (IOL) is implanted simultaneously.[13]

A posterior segment IOFB requires a vitrectomy, unless the tissue damage is minimal. The posterior hyaloid should always be removed, and any deep impact should be prophylactically treated against proliferative vitreoretinopathy (PVR) (see below). For the actual removal, the best tool to extract a ferrous IOFB is a strong intraocular magnet. For nonmagnetic IOFBs, a proper forceps or a lasso may be used. External electromagnets should not be used since they do not allow controlled extraction.[14, 15, 16, 17]

Rarely, a scleral cut-down is used.

If the IOFB has caused a deep impact (ie, involving the choroid), prophylactic chorioretinectomy is recommended. Using the highest setting of the diathermy machine, the probe is used to destroy the retina and the choroid around the impact site, thereby leaving a bare sclera to surround the impact site.[18] In early clinical tests, this procedure has proven to be very effective in preventing both PVR and radiating retinal folds. The same technique may be used if a chronic IOFB is found to be causing full-thickness folds in the macula, a pathologic condition that tends to be highly disturbing to the patient.[19]

Activity

No activity restriction is necessary once the wound heals and there is no need for positioning.

 

Medication

Medication Summary

The goal of pharmacotherapy is to reduce morbidity and to prevent complications, such as posterior synechia (pupillary dilation), inflammation (corticosteroids), and intraocular pressure (IOP) elevation.

Antibiotics

Class Summary

For use in every case (systemic and topical); intravitreal usually only if infection is present or the case is high risk.

Vancomycin (Vancocin, Vancoled, Lyphocin)

DOC for gram-positive coverage. Potent antibiotic directed against gram-positive organisms and active against Enterococcus species. Useful in the treatment of septicemia and skin structure infections. Indicated for patients who cannot receive, or have failed to respond to penicillins and cephalosporins, or have infections with resistant staphylococci. For abdominal penetrating injuries, it is combined with an agent active against enteric flora and/or anaerobes.

To avoid toxicity, current recommendation is to assay vancomycin trough levels after third dose drawn 0.5 h prior to next dosing. Use creatinine clearance to adjust dose in patients diagnosed with renal impairment.

Used in conjunction with gentamicin for prophylaxis in penicillin-allergic patients undergoing gastrointestinal or genitourinary procedures.

Ceftazidime (Ceptaz, Fortaz, Tazicef, Tazidime)

First-line choice for intravitreal gram-negative coverage. Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Arrests bacterial growth by binding to one or more penicillin-binding proteins.

Antifungals

Class Summary

Their mechanism of action may involve an alteration of RNA and DNA metabolism or an intracellular accumulation of peroxide that is toxic to the fungal cell.

Amphotericin B (Amphocin, Fungizone)

Produced by a strain of Streptomyces nodosus; can be fungistatic or fungicidal. Binds to sterols, such as ergosterol, in the fungal cell membrane, causing intracellular components to leak with subsequent fungal cell death.

 

Follow-up

Further Outpatient Care

Follow-up visits are necessary for at least 4 months to determine whether proliferative vitreoretinopathy has occurred. Rehabilitation service may be necessary if permanent visual impairment is present.

If retinal folds, radiating from a retinal impact site, develop and interfere with vision by reaching into the macula—and even seemingly inconspicuous folds can cause severe visual disturbance—late chorioretinectomy should be considered.[20]

Further Inpatient Care

Unless serious complications are present, the patient can be discharged shortly after surgery.

Educate the patient about the potential of both early complications (eg, intraocular pressure elevation) and late complications (eg, scarring).

Inpatient & Outpatient Medications

Topical antibiotics and corticosteroids in the early postoperative period are indicated.

Deterrence/Prevention

Safety eyewear made of polycarbonate (3 mm in thickness) virtually eliminates the risk of intraocular foreign bodies (IOFBs).

Complications

Endophthalmitis, corneal scarring, elevated intraocular pressure, cataract, retinal detachment, proliferative vitreoretinopathy, and metallosis (eg, chalcosis, siderosis) are possible complications.[21]

Prognosis

The prognosis is generally relatively good. Over one half of eyes with IOFB injury regain/retain reading vision.

Patient Education

Eye protection when partaking in risky activities (eg, hammering, mowing the lawn) is strongly recommended.[22]