Orbital cellulitis

Orbital cellulitis is the result of an infection affecting the fat and muscles posterior to the orbital septum, within the orbit but not involving the globe. It is usually due to the spreading of the infection from bacterial rhinosinusitis - as the ethmoid sinuses and orbits are separated by a thin plate called lamina papyracea, which is the route along which infection spreads.

It carries a high mortality rate. Orbital cellulitis is a medical emergency requiring hospital admission and urgent senior review.

Periorbital (preseptal) cellulitis is a less serious superficial infection anterior to the orbital septum, resulting from a superficial tissue injury (chalazion, insect bite etc...). Periorbital cellulitis can progress to orbital cellulitis.

Risk factors

• Childhood
  • Mean age of hospitalisation 7-12 years
• Previous sinus infection
• Lack of Haemophilus influenzae type b (Hib) vaccination
• Recent eyelid infection/ insect bite on eyelid (periorbital cellulitis)
• Ear or facial infection

Presentation

• Redness and swelling around the eye
• Severe ocular pain
• Visual disturbance
• Proptosis
• Ophthalmoplegia/pain with eye movements
• Eyelid oedema and ptosis
• Drowsiness +/- Nausea/vomiting in meningeal involvement (Rare)

Differentiating orbital from preseptal cellulitis

• reduced visual acuity, proptosis, ophthalmoplegia/pain with eye movements are NOT consistent with preseptal cellulitis