A blowout fracture is usually due to blunt injury to the eye/orbit e.g. a football/fist/bat hitting the eye.
A blunt force to the eye/orbit usually will not rupture the globe itself, but the consequential rise in intraorbital pressure may cause the orbit to fracture (usually) at its weakest point- usually the inferomedial wall (maxillary bone). The other theory is that the impact causes a ‘buckling’ effect, fracturing the orbit. The result can damage the globe, the extraocular muscles (particularly inferior rectus muscle causing diplopia and can cause pain on vertical movement of the eye) and nerves (particularly infraorbital nerve- causing hypoaesthesia of the cheek and upper gum), and any nearby vessels; and orbital contents may end up being forced into the maxillary sinus (this may cause the globe to recess deep into the orbit- enopthalmos- although this is usually initially masked by a build up of orbital oedema) and, conversely, air may escape from the sinus into the orbit (orbital emphysema).
A full ophthalmological examination should be done. There will usually be some ecchymosis (bruising) and/or oedema of the orbit, and the symptoms above will be noted too.
There may be signs of traumatic optic neuropathy (decreased visual acuity and ischaemic disc on fundoscopy) or haemorrhage within the eye.
CThead is the main investigation involved to visualise the fracture and degree of damage. IOP should also be measured regularly to ensure there is no risk of glaucoma/hypertensive damage.
Most management is in an outpatient setting, conservative and will not usually cause any major problems. However, surgical reconstruction may be required if there is:
- entrapment of the inferior rectus with diplopia (more commonly seen in paediatric ‘trap door’ or ‘white eye’ fractures which nick the inferior rectus)
- marked enophthalmos (>2mm 10-14 days post trauma)
- A large fracture (>= third of the orbital floor)- mainly for cosmetic purposes
Steroids and diuretics may reduce the initial oedema, and analgesia may be required, but these are only symptomatic relief.