Orbital cellulitis

• Orbital and peri-orbital cellulitis reflect a spectrum of disease which are differentiated by the anatomy of the orbital septum.
• Peri-orbital cellulitis refers to infection occurring anterior to the orbital septum (pre-septal) and orbital cellulitis refers to infection occurring posterior to the orbital septum (post-septal).
• Orbital cellulitis involves infection of the muscle and fat within the orbit, posterior to the orbital septum.
• It is much more common in children
• Orbital cellulitis is a serious sight-threatening condition. Approximately 11% of patients will have visual loss following orbital cellulitis
• Causes:

  • Most commonly local spread from acute bacterial sinusitis, typically from the paranasal sinuses
  • Extension of peri-orbital cellulitis
  • Orbit trauma (e.g. dog bite)
  • Spread from the teeth from recent surgery or dental infection
• Typical symptoms of orbital cellulitis include:

  • Erythema and swelling around the eye
  • Blurred vision
  • Painful eye movements
  • Change in colour vision
  • Fever
• Other important areas to cover in the history include:

  • Past medical history: previous episodes of eye disease including any previous episodes of peri-orbital/orbital cellulitis
  • History of precipitating cause: for example orbital trauma, sinusitis, or dental infection
  • Duration of symptoms
  • Laterality (unilateral or bilateral)
  • Severity of symptoms (worsening, stable or improvement in symptoms since start)
•  the following clinical examinations should be performed:

  • Nasal examination: looking for ipsilateral nasal discharge/mucus
  • Oral cavity examination: assessing oral hygiene, any evidence of dental disease, and any recent dental treatment of the upper molars
  • Examination of the eyes and vision: including assessment of visual fields, visual acuity, colour vision, relevant afferent pupillary defect (RAPD), light reflexes, proptosis measurement of intraocular pressure and slit lamp examination.
  • Neurological examination: cranial nerve examination including assessment for meningism
• Typical clinical findings in orbital cellulitis include:

  • Severe eye redness and swelling
  • Fever
  • Painful eye movements*
  • Reduced visual acuity and/or visual fields *
  • Proptosis *
  • Relevant afferent pupillary defect (RAPD): Marcus-Gunn pupil *
  • Chemosis * (inflammation of eyelids and conjunctiva)
  • Altered colour vision *(red-green tends to be the first colours lost)
• Red flags:

  • RAPD
  • Reduced visual acuity or visual fields
  • Proptosis
  • Painful eye movements
  • Chemosis (inflammation of eyelid and conjunctiva)
• Bilateral eye signs may indicate cavernous sinus thrombosis.
•  Nausea, vomiting, headache, neck stiffness may indicate intracranial involvement.
• Relevant laboratory investigations include:

  • Full blood count: may show elevated white cell count, particularly neutrophilia
  • C-reactive protein (CRP): may be elevated
  • Lactate: may be raised if the patient is septic
  • Blood cultures: the most common isolated organisms include Staphylococcus, Streptomyces species and Haemophilus
  • Microscopy, culture and sensitivity swabs: including swabs of the conjunctiva and nasopharynx
• Imaging:

  • If clinical exam of the eye is not possible, there are any red flags or a failure to improve
  • Contrast CT orbit, sinuses and brain
  • If meningeal signs develop, a LP is indicated
• Most common organisms:

  • Staphylococcus
  • Streptomyces
  • Haemophilus
• Management:

  • Emergency referral to ophthalmology and ENT
  • IV antibiotics for 7-10 days
  • If orbital collection - evacuation or drainage may be needed
• Complications of orbital cellulitis include:

  • Cavernous sinus thrombosis
  • Loss of vision
  • Intracerebral abscess
  • Meningitis
  • Death (rarely)