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Orbital Cellulitis

CRITICAL — Adnexa

Symptoms

  • acute-onset unilateral eyelid swelling, erythema, and deep-seated pain
  • pain with eye movement and diplopia (double vision)
  • decreased vision or "washed out" colors (advanced cases)
  • fever, headache, and malaise (common systemic features)
  • history of preceding sinus infection or upper respiratory symptoms

Clinical Findings

Clinical signature

  • hallmark: proptosis and restricted extraocular motility (ophthalmoplegia)
  • pain on eye movement: a critical early differentiator from preseptal cellulitis
  • chemosis (conjunctival swelling) and eyelid edema

Optic nerve compromise

  • relative afferent pupillary defect (rapd), decreased color vision, or disc edema
  • elevated iop due to orbital compartment syndrome

Systemic & atypical

  • black eschar on palate/nasal mucosa: suggests life-threatening mucormycosis
  • ams or bilateral involvement: suggests cavernous sinus thrombosis

Etiology

Sinusitis

  • ethmoid sinus (>90% in children) is the most common source of infection

Pathogens

  • s. aureus (including mrsa), s. pneumoniae, and h. influenzae
  • polymicrobial and anaerobes common in adults and dental sources
  • fungal (mucormycosis/aspergillus): consider in diabetics or immunocompromised

Red Flags

  • orbital vs preseptal: proptosis, motility restriction, and pain on movement are ONLY in orbital
  • optic nerve compression: rapid vision loss or rapd requires emergent decompression
  • intracranial extension: altered mental status (ams) or cranial nerve palsies
  • mucormycosis: high mortality in diabetics; requires emergent debridement

Investigations

Imaging (gold standard)

  • ct orbits and sinuses with contrast: evaluate for subperiosteal abscess (spa) and sinus source

Laboratory workup

  • cbc with differential, blood cultures (x2), and esr/crp
  • blood glucose and hba1c for all adults

Specialized

  • mri orbits/brain: if cavernous sinus thrombosis or intracranial extension is suspected
  • nasal endoscopy/biopsy: if fungal infection is suspected

Treatment

Medical management

  • iv antibiotics: vancomycin + ceftriaxone ± metronidazole (for anaerobes)
  • transition to oral antibiotics once improved; total course 2–3 weeks

Surgical intervention

  • drainage of subperiosteal or orbital abscess if large, progressing, or nerve is threatened
  • emergent surgical debridement for suspected fungal (mucor) infection

Complications

  • lateral canthotomy/cantholysis if orbital compartment syndrome (high iop/nerve threat) exists

Clinical Pearl

the preseptal vs orbital distinction is made by proptosis, pain on eye movement, motility restriction, and rapd — all absent in preseptal, present in orbital. ct orbits with contrast is mandatory if any of these are present. in a diabetic or immunocompromised patient with periorbital infection, rule out mucormycosis before considering routine orbital cellulitis — delay kills.

Differential Diagnosis

  • • preseptal cellulitis (lacks proptosis/motility restriction/pain on movement)
  • • thyroid eye disease (subacute, bilateral, no fever)
  • • idiopathic orbital inflammation (pseudotumor)
  • • cavernous sinus thrombosis (bilateral signs, ams, cn palsies)
  • • mucormycosis (immunocompromised, necrotic tissue)

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