Trauma-Induced Extrusion of an Ex-PRESS Glaucoma Shunt Presenting as an Intraocular Foreign Body

A 61-year-old non–English-speaking woman went to an outside emergency department after falling and hitting her head on the edge of a piece of furniture. She complained of decreased vision and pain in the left eye. A computed tomographic scan demonstrated intraocular air with a metallic foreign body in the left eye (figure 1). The woman was referred to our institution for further evaluation.

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figure 1. Axial computed tomography demonstrates a radio-opaque object in the anterior globe. The object appears to be in the eye wall. Note the associated air suggestive of globe penetration.

We were unable to obtain additional history from the patient owing to a language barrier. Visual acuity was 20/80 OD and 20/200 OS. Intraocular pressure was 10 mm Hg OD and 12 mm Hg OS. The anterior segment examination revealed inferonasal loss of the iris stroma in both eyes, which was consistent with iris colobomas. Two millimeters above the left superior limbus, there was a Seidel-positive wound through which a smooth piece of metal was protruding through both conjunctiva and sclera. On further inspection, a dislocated Ex-PRESS shunt (marketed by Optonol Ltd, Zug, Switzerland; and in the United States by CIBA Vision, Duluth, Ga) was suspected (figure 2A). The posterior segment examination revealed bilateral inferonasal colobomas.

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figure 2. A, The Ex-PRESS shunt is tilted on its side and has eroded through the conjunctiva. B, The shunt immediately after being removed from the eye wall. Note the external flange and internal spur, which are designed to keep the shunt in place in the sclera.

After informed consent was obtained, the patient was taken to the operating room. A limbus-based conjunctival flap was created. The metallic shunt was removed and confirmed to be an Ex-PRESS shunt (Figure 2B). A small scleral track was present; this was not sutured closed. Both the conjunctival wound and flap were reapposed with sutures. One month postoperatively, the patient’s eye pain had resolved, the visual acuity had improved to 20/80, and the intraocular pressure increased to 14 mm Hg. There were no postoperative complications.

The Ex-PRESS miniature glaucoma implant is a small, stainless steel shunt that is implanted beneath the conjunctiva through a full-thickness sclerotomy and into the anterior chamber for treatment of open-angle glaucoma.¹ Several studies suggest that the shunt is effective at reducing intraocular pressure. There have been no reports of shunt dislocation. however, a potential complication is spontaneous shunt exposure. One study² documented conjunctival erosion in 4 of 36 cases whereas another study³ reported none in 11 cases. In 24 patients in whom the shunt was implanted under a scleral flap treated with mitomycin C, there were no reports of conjunctival erosion.⁴ However, as our case illustrates, blunt trauma to the eye can cause the shunt to become dislocated and exposed.

In contrast to many of the current glaucoma shunt devices currently available, the Ex-PRESS shunt is metallic. On a computed tomographic scan or plain radiograph, the Ex-PRESS shunt will appear as a radio-opaque object, and if individuals are not familiar with this device, it may cause undue concern. In the setting of trauma, the Ex-PRESS shunt may dislocate and partially extrude. This extrusion, combined with the presence of intraocular air and metal on imaging, may simulate an intraocular foreign body. Differentiating the Ex-PRESS shunt from an intraocular foreign body may allow for better counseling the patient for surgery and aid in planning the surgical repair.

Correspondence: Dr Garg, Department of Ophthalmology and Visual Sciences, Barnes Retina Institute, Washington University, 660 S Euclid, Campus Box 8096, St Louis, MO 63110 (garg@vision.wustl.edu).

Financial Disclosure: None.