27.2  Intraocular Foreign Body

The identification of intraocular foreign bodies (IOFB) is a critical step in the evaluation of penetrating ocular injuries.[1,2] The visual acuity, pupil examination, intraocular pressure, and extent of injury visible on examination should be carefully documented (Figure 27.2.1).[3,4] All patients should undergo thin-cut 3-mm non-contrast orbital CT scans prior to surgery.[5] Gentle B-scan ultrasonography may provide additional useful information if visualization of the fundus is obscured. Concern for expulsion of intraocular contents may preclude B-scan ultrasonography until the globe is closed.[6,7]

Unless the IOFB has entered the eye through the cornea, conjunctival peritomy should be performed to evaluate the extent of the scleral injury. Prolapsed uveal tissue should be gently reposited into the eye, or excised, dependent upon the viability of the tissue. Prolapsed vitreous or lens fragments are generally cut flush with the corneoscleral wound. The wounds should be closed completely prior to intraocular manipulation (See Chapter 27.1 Open Globe Injuries).

If the visualization of the fundus is impaired (e.g. hyphema, cataract), this needs to be addressed next. As always, if an infusion cannula cannot be visualized through the pupil, an anterior chamber infusion line should be placed until this has been rectified. Anterior chamber washout and/or lensectomy may be required. If lensectomy is performed and there is adequate zonular support, the sulcus should be left for future placement of an intraocular lens. In cases of more advanced retinal disease, the patient may be left aphakic and the capsule removed.

Vitrectomy can only proceed safely once there is sufficient view through the pupil of the intraocular instruments.[12,13,14] A long infusion line (e.g. 6 mm) can be placed trans pars plana and visualized through the pupil to avoid inadvertent suprachoroidal infusion. If there is concern for an occult retinal detachment or choroidal effusion or hemorrhage, then it is often preferable to assess the situation with a light-pipe prior to creation of the third sclerostomy.

Although the IOFB will often be addressed last, the nature of the posterior segment injury and the location of the IOFB should be determined. Next, a core vitrectomy is performed, the hyaloid is elevated if a PVD is not present and it is deemed safe to do so (this might be skipped in a young patient to avoid iatrogenic tears resulting from a very adherent vitreous), and a peripheral vitrectomy with scleral depression is performed to simultaneously evaluate for anterior pathology.

Determine the size and composition of the IOFB. A pars plana incision will need to be created with an MVR (or keratome) blade that is at least the minimum dimension of the IOFB. The IOFB may require removal through the limbus or through a clear corneal wound (if the patient is aphakic). These steps should be performed as the final steps in order to minimize hypotony (Figure 27.2.3).

Multiple instruments can be used to lift the IOFB off the retina including IOFB forceps (such as the Rappazzo IOFB forceps), a soft tip cannula, or a magnet.[15] If linear, the IOFB should be grasped near one end so that it is easier to remove (Figure 27.2.4). A chandelier can be placed to permit bimanual reorientation. If the IOFB is embedded in retina and/or choroid, then endodiathermy around the retinal entry site and elevation of the intraocular pressure may assist in hemostasis. For magnetic IOFBs, on occasion there may be a role for use of an intraocular or external magnet.