Describe open globe injury and the management of an intraocular foreign body.

Recognition and Initial Management

• An open globe injury is a full-thickness wound of the eyewall — the cornea, the sclera or both.
• It is a surgical emergency, and the outcome depends more on correct initial handling than on any subsequent manoeuvre.
• Signs OF AN open globe — a visible full-thickness wound; a peaked, teardrop or eccentric pupil; uveal prolapse appearing as a dark knuckle of tissue at the wound; a shallow anterior chamber in an anterior wound or an abnormally deep one in a posterior rupture; hypotony; a positive SEIDEL test, in which concentrated fluorescein is diluted by a stream of escaping aqueous; bullous subconjunctival haemorrhage through 360 degrees; and reduced ocular movement

Intraocular Foreign Bodies

• The diagnosis IS made from the history. A high-velocity metallic fragment from hammering metal on metal, chiselling, grinding or drilling produces a minute, self-sealing entry wound.
• The commonest sites of entry are the cornea and the limbus; the fragment may lodge in the anterior chamber, the angle, the lens, the vitreous or the retina
• Investigation — CT of the orbits with thin (1 mm) cuts is the standard, detecting metallic and most other fragments; plain radiography where CT is unavailable; and B-scan ultrasound, which is useful once the globe is closed but is avoided in an open globe. MRI IS absolutely contraindicated where the material may be metallic, since the magnetic field can move the fragment through the eye
• Note that wood and some plastics are poorly seen on CT and may be mistaken for air; where an organic foreign body is suspected the index of suspicion must override the imaging

• Removal — an anterior chamber fragment through a limbal incision; a posterior segment fragment by pars plana vitrectomy with intraocular forceps, which is now standard and allows the retina to be assessed and treated at the same time; an external magnet is now rarely used
• The greatest danger is endophthalmitis, whose incidence after a penetrating injury with a retained foreign body is substantial — and bacillus cereus is the feared organism, particularly with soil contamination, causing a fulminant panophthalmitis with corneal ring abscess and fever that can destroy the eye within hours
• Prophylaxis — systemic and intravitreal antibiotics at the time of primary repair where contamination is likely; and a high index of suspicion afterwards
• Complications — endophthalmitis; traumatic cataract; retinal detachment; proliferative vitreoretinopathy, which is the main cause of late failure; siderosis or chalcosis; glaucoma; and sympathetic ophthalmitis
• A negative Seidel test does not exclude a wound that has already self-sealed.
• Never remove an impaled foreign body outside theatre; it may be tamponading the wound and removal can empty the eye
• Never reposit prolapsed uvea outside theatre; cover it, shield the eye and transfer
• Repair within twenty-four hours where possible, under general anaesthesia with a non-depolarising relaxant
• Restore integrity first and anatomy second; definitive reconstruction belongs to a later operation