Injuries involving the eye and adjacent structures

Corneal abrasions and ulceration

The cornea is frequently damaged by trauma and foreign bodies (Fig. 36.16). Ulceration can occur with infection or after damage to the facial nerve (Chapter 34). Post herpetic ulceration is common and serious if not treated. Fluorescein instillation can show up cornea) ulceration at an early stage. Treatment is by protection (eye pads, tarsorrhaphy or a bandage contact lens), and antibiotics topically and systemically: 0.5 per cent chloramphenicol or ofloxacin eye drops are commonly used. The eye is made more comfortable by the use of mydriatics such as homatropine or cyclopentolate. Herpes simplex ulcers are treated with acyclovir ointment. In countries in the Far and Middle East chronic infection with trachoma can cause corneal opacification and blindness. Cornea) grafting is the only cure for an opaque cornea. Osteo—odonto keratoprosthesis can be done in very severe cases of opaque corneas which are not suitable for grafting. Acanthoemeba is a serious cause of cornea) infection. This fungal corneal infection usually follows the use of contact lenses. These rare cases need specialist treatment.

Blunt injuries to the eye and orbit

The floor of the orbit is its weakest wall, and in blunt trauma, such as fist injuries, it is often fractured without fractures of the other walls. This is called a blow-out fracture. Clinical signs are enophthalmos, bruising around the orbit and limitation of upward gaze and diplopia. This occurs when the extraocular muscles become trapped in the fracture, and can be identified as a soft tissue mass in the antrum on a radiograph (Fig. 36.17), although tomograms or CT scans may be necessary. Surgical repair of the orbital floor with freeing of the trapped contents may be necessary if troublesome diplopia persists. Large doses of steroids sometimes relieve symptoms in acute cases. If an orbital haemorrhage is too extensive to examine the eye, it may be necessary to examine the eye under anaesthesia because there may be a hidden perforation of the globe. Injuries to the lids and lid margins must be repaired, and if the lacrimal canaliculi are damaged they should be repaired if possible, especially the lower canaliculus, because 95 per cent of tear drainage goes through it.

Blunt injuries can also cause damage to the optic nerve which can result in blindness and a total afferent nerve defect (Fig 36.18 and Fig 36.19).

Concussional injuries

Concussional injuries of the eye can give rise to several problems, which include the following.

 Hyphaema (blood in the anterior chamber) (Fig. 36.20). Bed rest and sedation are advised because the main danger in this condition is secondary bleeding, resulting in an acute rise in intraocular pressure and blood staining of the cornea. The use of antifibrinolytic agents (e-aminocaproic acid) has been advocated and, if the pressure rises, surgery to wash out the blood may be necessary.

  Subluxation of the lens can be suspected if the iris, or part of the iris, ‘wobbles’ on movement .

Secondary glaucoma often associated with recession of the angle.

Retinal and macular haemorrhages and choroidal tears (Fig. 36.21).

Retinal dialysis, which may lead to a retinal detachment and permanent damage to vision (Fig. 36.22).

Penetrating eye injuries

These occur when the globe is penetrated, often in road traffic and other major accidents (Fig. 36.23), and also in injuries from sharp instruments. In the UK, the seat belt law has reduced this type of eye injury by up to 73 per cent in some series. The presence of an irregular pupil suggests prolapse of the iris, and should arouse the suspicion of a penetrating injury. Treatment is immediate surgery to restore the integrity of the globe. If a perforation is suspected, extensive eye examination should not be attempted before anaesthesia because this may lead to further extrusion of the intraocular contents. In severe corneal and intraocular injuries, primary cornea) grafting, lensectomy and vitrectomy have considerably improved the visual prognosis; these must be done by an experienced eye surgeon. Injuries to the optic nerves must also be excluded in severe accidents.

Intraocular foreign bodies

Intraocular foreign bodies must always be excluded when patients attend the accident and emergency department with a history of working with a hammer and chisel. Radiography of the orbits should always be performed, and ferrous and copper foreign bodies should always be removed. Beta-scan ultrasonography can also assist in localising foreign bodies when a vitreous haemorrhage is present. CT can be used, but MRI is contraindicated for orbital lesions.

Burns

Radiation burns

These occur after exposure to ultraviolet radiation after arc welding or excessive sunlight (snow blindness) and sun lamps. Such burns cause intense pain and photophobia due to a keratitis, which may start some hours after exposure. Mydriatic and local steroid drops ease the condition, and healing usually occurs after 24 hours.

Thermal burns

If these involve the full thickness of the lids, corneal scarring may occur, and immediate skin grafting to the lids is necessary. A splash of molten metal may cause marked local necrosis, and may lead to permanent corneal scarring. Treatment is to remove any debris by irrigation, and to instil local atropine, antibiotics and steroids to prevent superadded infection and scarring.

Chemical burns

Chemical burns, and especially alkali burns, can be serious because ocular penetration occurs quickly and ischaemic necrosis can result. Immediate irrigation will ensure that the chemical is diluted as much as possible, and all particles should be removed from the fornices. Treatment can then be continued as with thermal burns. Well-fitting goggles should prevent such injuries (Fig. 36.24).