What is the difference between orbital cellulitis and periorbital cellulitis?

Difference Between Orbital and Periorbital Cellulitis

Orbital cellulitis and periorbital cellulitis are distinct clinical entities with different anatomical involvement, etiologies, clinical presentations, and management approaches, with orbital cellulitis being more serious and potentially sight- and life-threatening. 1

Anatomical Differences

• Periorbital (Preseptal) Cellulitis:

  • Infection limited to the eyelids and soft tissues anterior to the orbital septum
  • Does not involve the orbital contents
  • Also referred to as preseptal cellulitis or inflammatory edema 2, 1

• Orbital Cellulitis:

  • Infection of tissues posterior to the orbital septum within the bony orbit
  • Involves the orbital contents
  • Can progress to subperiosteal abscess, orbital abscess, or cavernous sinus thrombosis 1, 3

Clinical Presentation

Periorbital Cellulitis

• Eyelid erythema and edema
• No proptosis
• No limitation of extraocular movements
• Normal visual acuity
• No pain with eye movement
• More common in children under 5 years 4, 5

Orbital Cellulitis

• Eyelid erythema and edema
• Proptosis (forward displacement of the eye)
• Limitation of extraocular movements/diplopia
• Decreased visual acuity
• Pain with eye movements
• Chemosis (conjunctival edema)
• More common in children older than 5 years 1, 3, 5

Etiology

Periorbital Cellulitis

• Common causes:
  • Localized trauma to the periorbital area
  • Upper respiratory tract infections (68%)
  • Skin infections (impetigo, insect bites)
  • Bacteremia (especially in young children) 1, 4, 5

Orbital Cellulitis

• Common causes:
  • Sinusitis (79-90% of cases, especially ethmoid sinusitis)
  • Direct extension from periorbital cellulitis
  • Trauma with foreign body
  • Hematogenous spread 2, 4, 5

Microbiology

• Both conditions commonly involve:
  • Staphylococcus aureus
  • Streptococcus pyogenes
  • Streptococcus pneumoniae 1, 4

Diagnostic Approach

Clinical Evaluation

• Careful assessment for signs distinguishing orbital from periorbital involvement:
  • Proptosis
  • Limitation of extraocular movements
  • Pain with eye movement
  • Visual acuity changes 1

Imaging

• Periorbital Cellulitis:

  • Imaging not routinely required for typical cases

• Orbital Cellulitis or Suspected Complications:

  • Contrast-enhanced CT scan of the paranasal sinuses and orbits is indicated
  • MRI with contrast preferred when intracranial complications are suspected 2, 1

Management

Periorbital Cellulitis

• Often managed with oral antibiotics as outpatients
• Common regimens include dicloxacillin, cephalexin, clindamycin, or amoxicillin-clavulanate
• MRSA coverage may be necessary in high-prevalence areas
• Daily follow-up until definite improvement 1

Orbital Cellulitis

• Requires hospitalization for intravenous antibiotics
• Surgical intervention indicated for:
  • Subperiosteal or orbital abscess formation
  • Inadequate response to medical therapy
  • Evidence of bone erosion on imaging
• Multidisciplinary consultation with ophthalmology, otolaryngology, and infectious disease specialists 2, 1, 3

Complications

Periorbital Cellulitis

• Progression to orbital cellulitis
• Bacteremia (especially in young children)
• Meningitis (rare) 5

Orbital Cellulitis

• Vision loss
• Intracranial extension (meningitis, brain abscess)
• Cavernous sinus thrombosis
• Neurological deficits
• Death (rare with appropriate treatment) 1, 3

Clinical Pearls and Pitfalls

• Warning signs requiring urgent ophthalmology referral include pain with eye movements, movement restriction/diplopia, proptosis, or vision changes 1
• Worsening symptoms despite 24-48 hours of antibiotic therapy suggests progression to orbital cellulitis 1
• Altered mental status or severe headache may suggest intracranial involvement 1
• Surgical intervention is necessary in approximately 49% of orbital cellulitis cases 6
• Delayed diagnosis or inadequate treatment of complications can lead to permanent vision loss, neurological deficits, or even death 1