Orbital Cellulitis

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Orbital cellulitis is a serious bacterial infection involving the soft tissues posterior to the orbital septum, which can lead to vision loss and intracranial complications if untreated.

Aetiology

  • Sinusitis related spread: most common cause, especially from the ethmoid sinuses.
  • Trauma: penetrating injury, insect bites, or surgery-related infections.
  • Hematogenous spread: bacteremia from distant infections.
  • Local spread: extension from preseptal cellulitis or dacryocystitis.
  • Common pathogens: Staphylococcus aureus (including MRSA), Streptococcus species, Haemophilus influenzae (in children), and anaerobes.

Pathophysiology

  • Bacterial invasion of the orbital tissues leads to inflammation and oedema.
  • Increased intraorbital pressure can result in optic nerve compression.
  • Potential progression to abscess formation, cavernous sinus thrombosis, or meningitis.

Risk Factors

  • Recent upper respiratory tract infection or sinusitis.
  • Ocular trauma or recent eye surgery.
  • Dental infections.
  • Immunosuppression (e.g., diabetes, HIV, steroid use).
  • Preseptal cellulitis progressing to orbital involvement.

Signs and Symptoms

  • Ocular pain and tenderness.
  • Proptosis (bulging of the eye).
  • Ophthalmoplegia with pain on eye movement.
  • Decreased visual acuity.
  • Periorbital swelling and erythema.
  • Fever and systemic symptoms (malaise, headache).

Investigations

  • CT orbit, sinuses and brain with contrast: confirms diagnosis, identifies abscess formation.
  • Blood cultures: if systemic involvement is suspected.
  • Swab for microbiology: if purulent discharge is present.
  • Full blood count (FBC) + CRP/ESR: raised white cell count and raised CRP/ESR suggests infection.

Management

1. Immediate Management:

  • Urgent hospital admission and ophthalmology review.
  • Broad spectrum IV antibiotics (co-amoxiclav or ceftriaxone + metronidazole; vancomycin if MRSA suspected) are generally started.
  • Supportive care (IV fluids, analgesia, fever management).

2. Surgical Intervention:

  • Drainage of orbital or subperiosteal abscess if present.
  • Endoscopic sinus surgery if underlying sinusitis is contributing.

3. Monitoring and Follow-Up:

  • Regular assessment of visual acuity and eye movements.
  • Switch to oral antibiotics once clinical improvement is noted (7-10 days total treatment).

4. Referral:

  • Ophthalmology: all cases require urgent specialist input.
  • ENT: if sinus involvement necessitates drainage.
  • Microbiology: if non-responsive to empirical antibiotics.
Eye DiseasesmypanotesOrbital Cellulitis