Orbital Cellulitis

Orbital cellulitis is infection of the soft tissues posterior to the orbital septum, within the orbit. It is a vision threatening and life threatening emergency that needs urgent imaging and intravenous antibiotics.

• Most cases arise from adjacent paranasal sinusitis, particularly the ethmoid sinus, through the thin lamina papyracea or via valveless veins; others follow trauma, dental infection, eyelid or facial infection, ocular surgery, and bacteraemia.
• Organisms: Streptococcus (anginosus group, pneumoniae, pyogenes), Staphylococcus aureus including MRSA, Haemophilus influenzae, and anaerobes (Peptostreptococcus, Bacteroides); in adults with diabetes or immunosuppression, consider mucormycosis and Aspergillus; polymicrobial infection is common in older children.
• Staging by progression: inflammatory oedema, orbital cellulitis, subperiosteal abscess, orbital abscess, and cavernous sinus thrombosis.
• More frequent in children aged 5 to 10 years, in whom subperiosteal abscess is common.

• Fever, malaise, headache, eyelid erythema and oedema, chemosis, painful and restricted eye movements, proptosis, diplopia, and visual loss.
• Signs of optic nerve compromise: reduced acuity, dyschromatopsia, relative afferent pupillary defect, disc swelling, and raised intraocular pressure.
• Features of intracranial extension: severe headache, drowsiness, meningism, seizures, cranial nerve palsies, and bilateral involvement (cavernous sinus thrombosis).
• Black necrotic eschar of the nose or palate in diabetic ketoacidosis or immunosuppression suggests mucormycosis.

• Examination of vision, pupils, colour vision, proptosis, eye movements, and intraocular pressure, with serial documentation every 2 to 4 hours initially.
• Contrast enhanced CT of orbits, sinuses, and brain (the investigation of choice): diffuse fat stranding, rim enhancing subperiosteal or orbital abscess, sinus disease, and intracranial extension. MRI with venography for cavernous sinus thrombosis or intracranial complications.
• Laboratory: full blood count, CRP, blood cultures (before antibiotics), glucose and HbA1c, and renal function; culture of sinus pus, abscess material, and nasal swab.
• Lumbar puncture only if meningitis is suspected and after imaging.

• Admit for intravenous therapy with joint ophthalmology and ENT care and neurosurgical input when needed.
• Empirical intravenous antibiotics (adult):
  • Ceftriaxone 2 g every 12 hours (or cefotaxime 2 g every 6 to 8 hours) with vancomycin 15 to 20 mg/kg every 8 to 12 hours (adjust to trough 15 to 20 mg/L or area under the curve targets) and metronidazole 500 mg every 8 hours; or piperacillin tazobactam 4.5 g every 6 to 8 hours with vancomycin; or ampicillin sulbactam 3 g every 6 hours.
  • Children: ceftriaxone 100 mg/kg/day in 1 to 2 divided doses (maximum 4 g/day), vancomycin 40 to 60 mg/kg/day in 3 to 4 doses, and metronidazole 30 mg/kg/day in 3 doses when anaerobes are possible.
  • Continue intravenous therapy until clear improvement (usually 3 to 7 days) and afebrile, then complete 2 to 3 weeks in total (up to 4 to 6 weeks with abscess or intracranial extension) with oral amoxicillin clavulanate 625 mg every 8 hours (child 45 mg/kg/day amoxicillin component in 2 to 3 doses) or clindamycin 300 to 450 mg every 6 to 8 hours.
• Nasal decongestion: oxymetazoline 0.05 percent spray twice daily for 3 days, and saline irrigation.
• Systemic corticosteroids may be added after 24 to 48 hours of antibiotics in selected children with sinus related subperiosteal abscess, but evidence is limited; avoid when fungal disease is possible.
• Urgent surgical drainage (endoscopic sinus surgery with orbital decompression and abscess drainage) when: visual acuity falling or relative afferent pupillary defect, large abscess (over 10 mm) or medial abscess with mass effect, intracranial extension, age over 9 years, frontal sinus involvement, no improvement or worsening after 24 to 48 hours of antibiotics, or gas forming organisms. Small medial subperiosteal abscess in a young child with normal vision may be tried with antibiotics under strict monitoring.
• Suspected invasive fungal sinusitis (mucormycosis in diabetic ketoacidosis, haematological malignancy, or neutropenia): immediate liposomal amphotericin B 5 to 10 mg/kg/day intravenously, urgent surgical debridement, correction of acidosis and hyperglycaemia, and, after stabilisation, posaconazole or isavuconazole step down; aspergillosis: voriconazole 6 mg/kg every 12 hours for 2 doses then 4 mg/kg every 12 hours.
• Cavernous sinus thrombosis: high dose antibiotics, and anticoagulation (low-molecular-weight heparin enoxaparin 1 mg/kg twice daily) in selected cases.
• Emergency lateral canthotomy and cantholysis for orbital compartment syndrome with vision loss, markedly raised intraocular pressure, and tense proptosis.
• Complications: permanent visual loss (optic neuropathy, central retinal artery occlusion, exposure keratopathy), ophthalmoplegia, meningitis, brain abscess, cavernous sinus thrombosis, and death.