From the Eye Hospital of Wenzhou Medical College, Wenzhou, China.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Fang Ai-Wu MD, Eye Hospital of Wenzhou Medical College, Wenzhou 325003, China.
Foreign bodies in the anterior chamber angle are rare eye injuries. Retained foreign bodies can cause inflammation, iron sidrosis, copper chalcosis, endophthalmitis or injury to intraocular structures. To avoid these complications, the foreign bodies should be removed as soon as possible. The foreign bodies are usually removed by a microscopic surgery through limbal incisions. However, the limited visualization of anterior chamber angle makes the operation very difficult, especially for small and nonmagnetic foreign bodies. In this case presentation, we described a new technique to remove foreign bodies in the angle under endoscopic guidance. In addition, we demonstrated the obvious benefits of ultrasound biomicroscopy (UBM) to assist in localization of foreign bodies in the ocular anterior segment.
A 31-year-old man presented with redness and decreased vision in his left eye 1 day after a small particle hit his left eye while hammering on metal. Upon examination, his left eye had a mild injected conjunctiva, clear cornea with a 1 mm self-healed laceration wound paracentrally, deep anterior chamber with 1+ cells and flare, round reactive pupil, clear lens with a small triangular rupture in the anterior capsule (Fig. 1A), normal posterior segment and normal intraocular pressure. Visual acuity (uncorrected) was 20/20 right eye (OD) and 20/25 left eye (OS). Examination of right eye was within normal limits. A computed tomography (CT) revealed an intraocular foreign body in the left eye (Fig. 1B). Localization was further confirmed by goldman gonioscopy (Fig. 1C) and UBM examination (Fig. 1D), which revealed the foreign body impacted in the inferior angle at 6:30 position.
Figure 1. (A) Slitlamp View of the Left Eye Showed a Mild Conjunctival Injection, a 1mm Full-Thickness Self-Healed Corneal Wound and a Small Triangular Rupture in the Anterior Lens Capsule (arrow), Without Evidence of Cataract Formation. (B) A Coronal CT Scan Revealed Small Dense Radio-Opaque Intraocular Foreign Body (arrow) at 6:30 Position. (C) Gonioscopic View of the Left Eye Showed a Silvery Metallic Fragment (arrow) in the Inferior Angle at 6:30 Position. (D) Preoperative UBM View of the Left Eye Showed a Foreign Body (arrow) in the Inferior Angle at 6:30 Position. (E) Five Days After the First Surgery, UBM of the Left Eye Showed Peripheral Anterior Synechiae and the Foreign Body (arrow) Embedded in Angle Structures. (F) Intraoperative Photograph Showed the Removal of the Foreign Body by a Forceps Under Endoscopic Guidance.
The patient was admitted for surgery. After checked the localization of the foreign body with goniolens, forceps were used to attempt to remove the foreign body through a limbal incision at 12-o’clock. However, the translucent limbus and opaque overlying sclera made the surgical view too limited to grasp the foreign body. Moreover, as there was no obvious magnetic reaction, attempt to retrieve the foreign body with an external magnet through a limbal incision at 6:30 position also failed. The gonioscopy examination did not revealed the foreign body after the surgical procedures due to hyphema resulted by iris injury. The hyphema resoluted completely 5 days after the first surgery, and the foreign body still could not be detected by gonioscopy examination but a peripheral anterior synechiae was seen in the inferior angle. A repeated UBM showed hyperechoic shadow in the inferior angle suggesting that the foreign body was embedded in the angle tissue (Fig. 1E). After informed consent had been obtained, an endoscopy assisted surgical exploration was done under local anesthesia. A 2.0 mm scleral tunnel was made at 2-o’clock through which a 20 Gauge endoprobe (Endognost Schwind) was introduced into the anterior chamber. The inferior angle was watched clearly in the monitor. After the iris synechiae was lysed by viscoelastic injection, the foreign body was exposed. Under direct visual control assisted by endoscopy, the foreign body was removed with curved suture tying forceps (Fig. 1F). It was metallic in nature, nonmagnetic and 1 mm × 0.5 mm in size. On discharge, there were no signs of inflammation, and the visual acuity was identical to that found on admission. At follow up, the patient’s clinical condition was unchanged.
Intraocular foreign bodies in the anterior chamber angle are rare diseases which are usually accompanied with corneal penetration, iris or lens injury. Small foreign bodies that perforate the cornea and enter the anterior chamber may leave a self sealing corneal wound which may not need suture closure. Some small particles become lodged in the inferior angle if they do not penetrate the iris or lens. Inert, non toxic, sterile materials such as plastic and glass can be well tolerated in the eye without serious side effects. However, most intraocular foreign bodies occur from metal striking metal. Metal intraocular foreign bodies may result in siderosis or chalcosis within the eyes. Vegetable matter in the eye may also induce a severe response with endophthalmitis. Therefore, it is vital that these foreign bodies are removed without delay.
Since an accurate foreign body localization is critical for a diagnosis and surgery plan, appropriate ocular examination should be performed. Gonioscopy permits visualization of the foreign body in the anterior chamber angle. However, it is contraindicated in the cases of corneal opacity, hyphema and foreign bodies lodged inside the angle tissue. A CT scan is often used to make sure no other intraocular foreign bodies are present. However, it can not accurately localize foreign bodies and often misses small foreign bodies between the CT scan cuts. Additionally, the CT scan will not detect nonmetallic foreign bodies. The magnetic resonance imaging (MRI) is contraindicated because the foreign body may be metallic. In the past decades, UBM has shown its unique value in localizing and determining the extent of the foreign body in the anterior segment.1 For this case, the UBM supplied precise localization of the foreign body in the angle preoperatively and postoperatively, even though the foreign body was encapsulated in the angle tissue and could not be detected by gonioscopy. The UBM greatly facilitated seeking the foreign body during the second surgical exploration.
Usually, surgeons tend to remove the foreign bodies in the anterior chamber angle by grasping them through limbal incisions using forceps. Most time it can be well treated with the help of gonioscopy used intraoperatively. Some metallic foreign bodies that have magnetic characteristics can be retrieved by an intraocular or extraocular magnet. However, dealing with foreign bodies in anterior chamber angle is not always easy. As the gonioscopy examination can not be performed with intraocular operation at the same time,2 the limbus always obscures the surgical view and blind manipulation or iris/lens injuries are common during surgery. Although there are a few previous case reports on the successful use of magnets to remove foreign body in the anterior chamber angle through a limbal incision, this method was only suitable for magnetic foreign bodies.3 In our case, due to a poor view of the angle structure during surgery and the nonmagnetic nature of the foreign body, the first attempt to remove the foreign body by means of conventional limbal approach and extraocular magnet failed.
A potentially useful technique to counter the poor surgical view may be endoscopy. The first ophthalmic endoscope was introduced by Thorpe in 1934 for the extraction of nonmagnetic intraocular foreign bodies.4 Since then, endoscopy-assisted surgery has been increasingly used in ophthalmic surgery, such as vitrectomy,5 endoscopic-guided intraocular lens implantation6 and endoscopic laser cyclophotocoagulation7 etc. Endoscopy completely bypasses the problem of optical media opacities and “dead angles” of the eye which are common in a conventional intraocular surgery. This technique has a distinct advantage of better illumination, magnification and visualization of critical areas during intraocular surgery. It has been proven to be safe, simple and minimal invasive.
To the best of our knowledge, this is the first report of endoscopy-assisted retrieval of a foreign body in the anterior chamber angle. The method of removing small nonmagnetic foreign bodies in the angle assisted by endoscopy described here is a precise, safe, and quick precedure. The endoscopy ensures successful lysis of the peripheral iris synechiae and allows proper assessment of whether or not the foreign body has been grasped. It also allows surgeons to complete the operation through a small incision and decrease the risk of iris or lens injury. Our case demonstrates the endoscopy-assisted surgery can be an ideal technique for removal of foreign bodies in the anterior chamber angle, especially for small, nonmagnetic foreign bodies. In addition, proper diagnostic tests, including gonioscopy, CT, UBM should be used to aid in localization of foreign bodies in the anterior chamber. UBM has a unique role in detecting occult foreign bodies lodged in the angle tissue.
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