14.7 Intraocular Foreign Bodies

14.7Intraocular Foreign Bodies

14.7.1 Clinical Presentation

Fig. 14.69 See previous Þgure

Fig. 14.71 A defect in the iris where an IOFB has entered, shown on diffuse illumination and transillumination

Fig. 14.74 An example of a fragment of metal removed from an eye. Often the foreign bodies are made of alloy metals. Foreign bodies vary in size from 1 mm to a few millimetres. They are commonly metallic but may be of other substances also

Fig. 14.73 In this patient with IOFB, the entry can be seen throug the cornea, iris and lens

Fig. 14.75 A large intraocular foreign body is seen in the retina producing a whitened reaction around the foreign body

IOFBs are typically caused by striking metal on metal such as hammering on a chisel. IOFBs have been described from glass from car windscreens (Ghoraba 2002), plastic Þreworks and strimmers (Lambert and Sipperley 1983), organic material in rural settings, shotgun pellets (Alfaro et al. 1992; Morris et al. 1987b), graphite pencil lead (Hamanaka et al. 1999) and fragments from lawnmower blades (John et al. 1988). Diagnosis of ocular retention of a small foreign body depends on careful attention to the details and the circumstances of the injury and close scrutiny for evidence of ocular penetration, such as a small entry site in the anterior sclera and signs of vitreous disturbance. Immediate posterior segment damage after foreign body penetration is generally restricted to the site of ultimate impaction. Initially, local tissue whitening may be visible together with bleeding into the cortical gel in the vicinity of the impact site and along the ÔtrackÕ or path of the foreign

Fig. 14.76 In trauma, the history is an important means of determining the likely type of injury. This patient presented late with IOFB after initially describing to the referring doctor a blunt injury from an iron bar for which a rupture or laceration was repaired. During examination for a vitreoretinal opinion 3 weeks later, the wound was felt to be suspicious of IOFB, and the patient questioned again. He provided a prior history of possible IOFB from hammering concrete. The IOFB was seen on ultrasound and removed via PPV (see Figs. 14.77Ð14.78)

Fig. 14.77 See previous Þgure

Fig. 14.78 See Fig. 14.76

bodyÕs penetration through the gel. The integrity of the retina is usually secured by chorioretinal scarring around the foreign body, but a small retinal break, subsequently causing retinal detachment, may develop if the foreign body ricochets off the retina rather than impacting within it.

If the retina is damaged, RRD is reported in 25 % (Ahmadieh et al. 1994). IOFBs often sit in the vitreous cavity without causing retinal tear. Subsequently, Þbroblast proliferation may occur either locally at the impact site (encapsulating the foreign body or puckering and distorting the underlying and adjacent retina) or along the haemorrhagic track to form a trans-gel traction band. Visual loss depends on the particular site of impaction (macular, papillary or peripheral), on opacities in the media (cataract or vitreous haemorrhage) or retinal detachment.

14.7.1.1 Diagnostic Imaging

1.CT scanning, with thin sections, is the investigation of choice if the IOFB cannot be seen on fundoscopy.

2. X-ray. Screening for a suspected foreign body can be performed by plain X-ray.

3.Ultrasound examination may be valuable for detecting non-radiolucent foreign bodies, but is a relatively inefÞcient method for detecting small metallic foreign bodies, especially if they are embedded in the ocular coats. Foreign bodies can give rise to high amplitude echoes provided they are appropriately orientated to the sound beam; a variety of artefacts arising from metallic particles aid in their identiÞcation and localisation, but the main value of ultrasound is in determining the vitreoretinal complications of foreign body impaction.