gms | German Medical Science

Intraorbital foreign bodies occur with one sixth of orbital injuries. Most of them are metallic or glass particles; wooden foreign bodies are less common, but more often associated with infections. Case histories are not always revealing, especially with children or patients under alcohol or drug influence. Entry wounds are often small and may easily be overlooked. The detection of intraorbital foreign bodies can be difficult, depending on their constitution, especially with wooden or plastic foreign bodies. The indication for removing the foreign body mainly depends on its localisation and material, incidence of an orbital infection or vision impairments. Risks and advantages of removing foreign bodies should be cleared up exactly already during the preoperative stage. The objective of our study was to develop a therapy strategy with a risk and benefit estimation.

During the last 10 years, we treated altogether 12 patients having orbital foreign bodies. Diagnosis was made by CT-Scan. One patient received an additional MRI investigation for detecting a plastic foreign body. In the other cases, there existed metallic foreign bodies in nine patients, and wooden foreign bodies in two patients. 10/12 patients were operated, three of them in the course of an emergency treatment. Two patients received no further operative treatment because there had been made several extraction attempts elsewhere, but without success. 3 patients were operated through an endonasal approach, 4 through a facial (paranasal) incision, and in 3 cases a lateral orbitotomy was performed. Two patients already had no light perception during the preoperative stage, and five patients had reduced vision acuity.

A 44-year-old patient was referred to our hospital with an orbital trauma caused by a lawn mower. The clinical examination demonstrated a small entry wound, orbital haematoma, chemosis, double vision, and normal visual acuity. Computed tomography (CT) of the orbit showed a metallic foreign body in the anterior-medial superior part of the left orbit, the frontal sinus was intact, and there was no bulb injury. We removed the foreign body through a paranasal incision under partial removing of the orbital roof. Immediately afterwards, there was no more double vision and normal vision acuity. Preoperative antibiotics (amoxicillin) were administered.

The 20-year-old patient was referred to our department after an industrial accident. The CT-scan demonstrated a metallic foreign body located posterior to the globe, directly caudal-medial to the optic nerve. The double penetrating ocular injury was repaired primarily by the ophthalmologist. Preserved vision acuity was slightly perceived postoperatively. A navigation controlled attempt to surgically remove it by endonasal approach remained without success. In the clinical follow-up examination the patient was without discomforts, accordingly we made no further attempt to remove the foreign body, in order to avoid no further aggravation of the impaired vision.

This case involves a 68-year-old man who had an orbital trauma caused by a bicycle accident. Initially his vision was normal but then reduced in a period of 8 days down to complete blindness. When he first consulted a physician 13 days after the accident, the clinical investigation revealed a total ophthalmoplegia, ptosis, and chemosis. CT-scans in modified window setting demonstrated a wooden foreign body in the lower eyelid. Furthermore, a diffuse inflammation in the orbital apex was diagnosed.

The foreign body was removed and a decompression of the orbit and optic nerve was performed. In addition, i.v. antibiotics and corticosteroids were administered. Unfortunately, no visual improvement could be achieved anymore.

In eight cases the foreign body was removed successfully, in two cases the foreign body could not be detected, however, the latter concerned posterior located foreign bodies only. In all cases, the loss of function was directly correlated with the trauma and not with surgery itself. Both patients with a wooden foreign body had a severe orbital cellulitis. With one of these patients the visual acuity recovered completely. In the other case, there was no further visual improvement detectable.

Figure 1 [Fig. 1]

Orbital foreign bodies are an interdisciplinary challenge. The indication for removing the foreign body mainly depends on localisation and material, incidence of an orbital infection and impaired vision. While metallic foreign bodies are biological inert and usually well tolerated – with the exception of copper –, organic foreign bodies are frequently associated with acute inflammatory reactions [Ref. 7], [Ref. 8]. If not removed, they may cause serious complications like orbital cellulitis, orbital or cerebral abscess, meningitis, chronically draining fistula and blindness. Although there is no typical history of penetrating orbital injuries, persistent or recurrent orbital infection may suggest a retention of a foreign body like in case 3. Computed tomography (CT) is the first imaging modality with orbital trauma [Ref. 1]. CT-scanning is excellent with high-density-material like glass or metal. But especially with wooden or plastic foreign bodies detection may be difficult [Ref. 1], [Ref. 2], [Ref. 9], [Ref. 10], [Ref. 11]. Dry wood looks similar to air, whereas the density of green wood is more similar to that of the surrounding periorbital fat [Ref. 1], [Ref. 9], [Ref. 10], [Ref. 11]. Appropriate window setting may help distinguishing a wooden foreign body from air. Ultrasound may be helpful especially for the anterior part of orbit, but is considered less reliable than CT in determination of size, shape and site. High resolution MRI, using fast spin echo sequences, seems to be able to show small non-metallic intraorbital foreign bodies. Before performing MRI investigations, metallic foreign bodies must be surely ruled out.

Anterior located foreign bodies often cause double vision like in case 1. Depending on localisation they may be removed by lateral orbitotomy or endonasal approach. Removing of an anterior located metallic foreign body allows patients to undergo further investigational MRI (for other reasons) without reservations regarding dislodgement of the foreign body with potential complications.

Posterior located foreign bodies are often associated with significant ocular pathologies. Surgical treatment of a retained metallic foreign body should not cause further functional deficits. Most metals are inert, and if there is no pain, inflammation or increasing impairment the possible dangers of extraction in anatomically complicated regions must be weighed against the risk of leaving the foreign body in situ [Ref. 8].

Wooden foreign bodies are of porous consistence, and because of that they are microbial contaminated [Ref. 11]. In a CT, wooden foreign bodies mimic air and orbital fat. The density of wood has a wide range from -984 to 110 HU. Diagnoses are often difficult, but delays in diagnosis and management may lead to severe complications such as ophthalmia, orbital cellulites (like in case 3), orbital abscess or meningitis [Ref. 4], [Ref. 5]. In all cases careful clinical examination of the eye region is essential as entry wounds are small and may easily be overlooked. Relevance is often underestimated both by the patient and even the examining physician [Ref. 3], [Ref. 5]. Persistent pain, ptosis or ophthalmoplegia are suggestive of a retained orbital foreign body [Ref. 2], [Ref. 4]. Despite adequate antibiotic therapy early extraction is always advisable [Ref. 6].

Therapeutic management of orbital foreign bodies demands close interdisciplinary cooperation. A CT-scan is the first imaging modality with orbital trauma. According to our experience, anterior located foreign bodies are mostly easy to remove, whereas posterior located foreign bodies are difficult to be detected. Wooden orbital foreign bodies are less common than metallic ones, but more often associated with infections. To prevent serious complications and permanent visual impairment, immediate surgical therapy is necessary.