Life-threatening conditions - Part 2

In the second of two articles, Nicholas Phelps Brown describes more life-threatening conditions of which all eye care practitioners need to be aware

ACUTE PROPTOSIS
A very short history of forward bulging of the eye always constitutes a medical emergency. The causative conditions are all threatening to the eye, but not all are life-threatening. Acute proptosis may be due to:

Orbital cellulitis
The patient with orbital cellulitis presents with a painful red eye. There is eyelid swelling and redness. The patient may be febrile and when the patient is a child there may be nausea and vomiting. It is important to differentiate pre-septal orbital cellulitis from orbital cellulitis. Each requires urgent referral, but it is orbital cellulitis which is life-threatening. Orbital involvement is indicated by the additional presence of proptosis, chemosis, blurred vision and reduced eye movement. The pupil response may become reduced or absent. The fundus may show papilloedema.

Orbital cellulitis is the name given to a widespread inflammation due to bacterial infection of the orbit. It is classified by the anatomical site of the infection. Pre-septal orbital cellulitis is a superficial infection, sited anterior to the orbital septum and occurs most commonly in young children.

Orbital cellulitis proper involves the soft tissues within the orbit posterior to the orbital septum. This occurs more commonly in older children and in adults.

The infection commonly begins elsewhere in the body and the bacteria may gain access to the orbit from a number of different sites of origin.

The organism is commonly a virulent pathogen such as Staphylococcus or Streptococcus. The commonest origin of the infection is in the nasal sinuses and the ethmoid sinus is the most commonly involved. Other local sites from which a bacterial infection may spread to the orbit are a dental abscess and facial skin infections. Conjunctival infection, particularly that involving the lacrimal sac with dacryocystitis, may spread into the orbit.

Lastly, the arrival of the bacteria may be metastatic when the bacteria have been blood-borne from a site elsewhere in the body.

An orbital abscess may develop, occasionally anterior to the orbital septum, but more usually within the orbit. The infection may spread posteriorly into the cavernous sinus causing cavernous sinus thrombosis (see later). The sight may be lost as a result of orbital cellulitis by damage to the optic nerve or by invasion of the eye by the organism causing endophthalmitis (Figure 3).