Orbital Abscess

A collection of pus in the orbit, usually the complication of ethmoid or frontal sinusitis. It lies in the subperiosteal space (most common, medial wall in children) or within the orbital fat (intraorbital abscess).

• Stages of orbital infection: inflammatory oedema without pus (orbital cellulitis), subperiosteal abscess, orbital (intraconal) abscess, cavernous sinus thrombosis.
• Organisms: Streptococcus anginosus group, Staphylococcus aureus (including methicillin resistant), Streptococcus pneumoniae, Haemophilus influenzae, anaerobes (Peptostreptococcus, Bacteroides, Fusobacterium); polymicrobial infection common in patients over 9 years. Fungal (mucormycosis, Aspergillus) in diabetic ketoacidosis and immunosuppression.
• Sources: sinusitis, dental infection, trauma, post-surgical, dacryocystitis, spread from facial skin.

• Fever, malaise, periorbital swelling, erythema, proptosis (usually displaced inferolaterally with medial wall abscess), chemosis, painful and restricted eye movements, ptosis, and reduced vision.
• Compressive optic neuropathy: relative afferent pupillary defect, colour desaturation, raised intraocular pressure.
• Signs of intracranial extension: severe headache, vomiting, meningism, reduced consciousness, seizures.
• Sinus signs: nasal discharge, facial pain, frontal swelling (Pott puffy tumour).
• Rapid progression over hours in children.

• CT orbits and sinuses with contrast (urgent): rim enhancing collection beneath periosteum, proptosis, sinus opacification; extension to cavernous sinus and cranium needs MRI and venography.
• Full count, CRP, blood cultures before antibiotics, swab or aspirate of pus from drainage, nasal swab; glucose and ketones in diabetes.
• Daily assessment of visual acuity, colour vision, pupils, motility and proptosis; document baseline.
• Examination of ENT for source, and dental review.

• Hospital admission; multidisciplinary care with ENT, ophthalmology and paediatrics or infectious disease.
• Intravenous antibiotics immediately (broad spectrum with Gram positive, Gram negative and anaerobic cover):
  • Ceftriaxone 2 g IV once daily (adult; child 50 to 100 mg/kg/day, maximum 4 g) plus metronidazole 500 mg IV every 8 hours (child 7.5 mg/kg every 8 hours); add vancomycin 15 to 20 mg/kg IV every 8 to 12 hours when methicillin resistant Staphylococcus aureus is likely.
  • Alternatives: piperacillin tazobactam 4.5 g IV every 8 hours, or amoxicillin clavulanate 1.2 g IV every 8 hours.
  • Duration: IV for at least 1 to 2 weeks until clinically improved, then oral amoxicillin clavulanate 625 mg three times daily to complete 3 to 4 weeks.
• Adjuncts: topical decongestant (oxymetazoline 0.05 percent, 2 sprays each nostril twice daily for 3 days), saline irrigation, analgesia, intraocular pressure control if raised.
• Surgical drainage (endoscopic sinus surgery with orbital drainage) is indicated for: visual compromise (relative afferent pupillary defect, reduced acuity), large abscess (over 10 mm), frontal sinus disease, age over 9 years, intracranial or cavernous extension, no improvement within 24 to 48 hours of antibiotics, recurrent abscess, or non-medial abscess. Small medial subperiosteal abscess in a child under 9 years with intact vision can be managed with antibiotics alone under close observation.
• Fungal: urgent surgical debridement and liposomal amphotericin B 5 mg/kg daily with correction of diabetic ketoacidosis.
• Complications: blindness, cavernous sinus thrombosis, meningitis, brain abscess, subdural empyema, osteomyelitis.