Introduction

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 caused by a spreading upper respiratory tract infection from the sinuses and 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.

Epidemiology

  • Incidence: 1.00 cases per 100,000 person-years
  • Peak incidence: 6-15 years
  • Sex ratio: 1:1
Condition Relative
incidence
Preseptal cellulitis10.00
Orbital cellulitis1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Aetiology

Risk factors
  • Childhood
  • Previous sinus infection
  • Lack of Haemophilus influenzae type b (Hib) vaccination
  • Recent eyelid infection/ insect bite on eyelid (Peri-orbital cellulitis)
  • Ear or facial infection

Clinical features

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)

Investigations

Investigations
  • Full blood count – WBC elevated, raised inflammatory markers.
  • Clinical examination involving complete ophthalmological assessment – Decreased vision, afferent pupillary defect, proptosis, dysmotility, oedema, erythema.
  • CT with contrast – Inflammation of the orbital tissues deep to the septum, sinusitis.
  • Blood culture and microbiological swab to determine the organism. Most common bacterial causes – Streptococcus, Staphylococcus aureus, Haemophilus influenzae B.

Differential diagnosis

Differentiating orbital from preseptal cellulitis

Management

Management
  • admission to hospital for IV antibiotics